Gene Therapy Retrovirus Vectors Explained

A retrovirus is any virus belonging to the viral family Retroviridae. All The genetic material in retroviruses is in the form of RNA molecules, while the genetic material of their hosts is in the form of DNA. When a retrovirus infects a host cell, it will introduce its RNA together with some enzymes into the cell. This RNA molecule from the retrovirus must produce a DNA copy from its RNA molecule before it can be considered part of the genetic material of the host cell. Retrovirus genomes commonly contain these three open reading frames that encode for proteins that can be found in the mature virus. Group-specific antigen (gag) codes for core and structural proteins of the virus, polymerase (pol) codes for reverse transcriptase, protease and integrase, and envelope (env) codes for the retroviral coat proteins (see figure 1). Figure 1. Genome organisation of retroviruses.

The process of producing a DNA copy from an RNA molecule is termed reverse transcription. It is carried out by one of the enzymes carried in the virus, called reverse transcriptase. After this DNA copy is produced and is free in the nucleus of the host cell, it must be incorporated into the genome of the host cell. That is, it must be inserted into the large DNA molecules in the cell (the chromosomes). This process is done by another enzyme carried in the virus called integrase (see figure 2).

Now that the genetic material of the virus is incorporated and has become part of the genetic material of the host cell, we can say that the host cell is now modified to contain a new gene. If this host cell divides later, its descendants will all contain the new genes. Sometimes the genes of the retrovirus do not express their information immediately.

Retroviral vectors are created by removal op the retroviral gag, pol, and env genes. These are replaced by the therapeutic gene. In order to produce vector particles a packaging cell is essential. Packaging cell lines provide all the viral proteins required for capsid production and the virion maturation of the vector. These packaging cell lines have been made so that they contain the gag, pol and env genes. Early packaging cell lines contained replication competent retroviral genomes and a single recombination event between this genome and the retroviral DNA vector could result in the production of a wild type virus. Following insertion of the desired gene into in the retroviral DNA vector, and maintainance of the proper packaging cell line, it is now a simple matter to prepare retroviral vectors (see figure 3).

One of the problems of gene therapy using retroviruses is that the integrase enzyme can insert the genetic material of the virus in any arbitrary position in the genome of the host. If genetic material happens to be inserted in the middle of one of the original genes of the host cell, this gene will be disrupted (insertional mutagenesis). If the gene happens to be one regulating cell division, uncontrolled cell division (i.e., cancer) can occur. This problem has recently begun to be addressed by utilizing zinc finger nucleases or by including certain sequences such as the beta-globin locus control region to direct the site of integration to specific chromosomal sites.

Gene therapy trials to treat severe combined immunodeficiency (SCID) were halted or restricted in the USA when leukemia was reported in three of eleven patients treated in the French X-linked SCID (X-SCID) gene therapy trial. Ten X-SCID patients treated in England have not presented leukemia to date and have had similar success in immune reconstitution. Gene therapy trials to treat SCID due to deficiency of the Adenosine Deaminase (ADA) enzyme continue with relative success in the USA, Italy and Japan.

As a reaction to the adverse events in the French X-SCID gene therapy trial, the Recombinant DNA Advisory Committee (RAC) sent a letter to Principal Investigators Conveying RAC Recommendations in 2003. In addition, the RAC published conclusions and recommendations of the RAC Gene Transfer Safety Symposium in 2005. A joint working party of the Gene Therapy Advisory Committee and the Committee on Safety of Medicines (CSM) in the UK lead to the publication of an updated recommendations of the GTAC/CSM working party on retroviruses in 2005.

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Gene Therapy Retrovirus Vectors Explained

Gene therapy – Wikipedia

In the medicine field, gene therapy (also called human gene transfer) is the therapeutic delivery of nucleic acid into a patient’s cells as a drug to treat disease.[1][2] The first attempt at modifying human DNA was performed in 1980 by Martin Cline, but the first successful nuclear gene transfer in humans, approved by the National Institutes of Health, was performed in May 1989.[3] The first therapeutic use of gene transfer as well as the first direct insertion of human DNA into the nuclear genome was performed by French Anderson in a trial starting in September 1990.

Between 1989 and February 2016, over 2,300 clinical trials had been conducted, more than half of them in phase I.[4]

Not all medical procedures that introduce alterations to a patient’s genetic makeup can be considered gene therapy. Bone marrow transplantation and organ transplants in general have been found to introduce foreign DNA into patients.[5] Gene therapy is defined by the precision of the procedure and the intention of direct therapeutic effect.

Gene therapy was conceptualized in 1972, by authors who urged caution before commencing human gene therapy studies.

The first attempt, an unsuccessful one, at gene therapy (as well as the first case of medical transfer of foreign genes into humans not counting organ transplantation) was performed by Martin Cline on 10 July 1980.[6][7] Cline claimed that one of the genes in his patients was active six months later, though he never published this data or had it verified[8] and even if he is correct, it’s unlikely it produced any significant beneficial effects treating beta-thalassemia.

After extensive research on animals throughout the 1980s and a 1989 bacterial gene tagging trial on humans, the first gene therapy widely accepted as a success was demonstrated in a trial that started on 14 September 1990, when Ashi DeSilva was treated for ADA-SCID.[9]

The first somatic treatment that produced a permanent genetic change was performed in 1993.[citation needed]

Gene therapy is a way to fix a genetic problem at its source. The polymers are either translated into proteins, interfere with target gene expression, or possibly correct genetic mutations.

The most common form uses DNA that encodes a functional, therapeutic gene to replace a mutated gene. The polymer molecule is packaged within a “vector”, which carries the molecule inside cells.

Early clinical failures led to dismissals of gene therapy. Clinical successes since 2006 regained researchers’ attention, although as of 2014[update], it was still largely an experimental technique.[10] These include treatment of retinal diseases Leber’s congenital amaurosis[11][12][13][14] and choroideremia,[15] X-linked SCID,[16] ADA-SCID,[17][18] adrenoleukodystrophy,[19] chronic lymphocytic leukemia (CLL),[20] acute lymphocytic leukemia (ALL),[21] multiple myeloma,[22] haemophilia,[18] and Parkinson’s disease.[23] Between 2013 and April 2014, US companies invested over $600 million in the field.[24]

The first commercial gene therapy, Gendicine, was approved in China in 2003 for the treatment of certain cancers.[25] In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia.[26]In 2012 Glybera, a treatment for a rare inherited disorder, became the first treatment to be approved for clinical use in either Europe or the United States after its endorsement by the European Commission.[10][27]

Following early advances in genetic engineering of bacteria, cells, and small animals, scientists started considering how to apply it to medicine. Two main approaches were considered replacing or disrupting defective genes.[28] Scientists focused on diseases caused by single-gene defects, such as cystic fibrosis, haemophilia, muscular dystrophy, thalassemia, and sickle cell anemia. Glybera treats one such disease, caused by a defect in lipoprotein lipase.[27]

DNA must be administered, reach the damaged cells, enter the cell and either express or disrupt a protein.[29] Multiple delivery techniques have been explored. The initial approach incorporated DNA into an engineered virus to deliver the DNA into a chromosome.[30][31] Naked DNA approaches have also been explored, especially in the context of vaccine development.[32]

Generally, efforts focused on administering a gene that causes a needed protein to be expressed. More recently, increased understanding of nuclease function has led to more direct DNA editing, using techniques such as zinc finger nucleases and CRISPR. The vector incorporates genes into chromosomes. The expressed nucleases then knock out and replace genes in the chromosome. As of 2014[update] these approaches involve removing cells from patients, editing a chromosome and returning the transformed cells to patients.[33]

Gene editing is a potential approach to alter the human genome to treat genetic diseases,[34] viral diseases,[35] and cancer.[36] As of 2016[update] these approaches were still years from being medicine.[37][38]

Gene therapy may be classified into two types:

In somatic cell gene therapy (SCGT), the therapeutic genes are transferred into any cell other than a gamete, germ cell, gametocyte, or undifferentiated stem cell. Any such modifications affect the individual patient only, and are not inherited by offspring. Somatic gene therapy represents mainstream basic and clinical research, in which therapeutic DNA (either integrated in the genome or as an external episome or plasmid) is used to treat disease.

Over 600 clinical trials utilizing SCGT are underway[when?] in the US. Most focus on severe genetic disorders, including immunodeficiencies, haemophilia, thalassaemia, and cystic fibrosis. Such single gene disorders are good candidates for somatic cell therapy. The complete correction of a genetic disorder or the replacement of multiple genes is not yet possible. Only a few of the trials are in the advanced stages.[39]

In germline gene therapy (GGT), germ cells (sperm or egg cells) are modified by the introduction of functional genes into their genomes. Modifying a germ cell causes all the organism’s cells to contain the modified gene. The change is therefore heritable and passed on to later generations. Australia, Canada, Germany, Israel, Switzerland, and the Netherlands[40] prohibit GGT for application in human beings, for technical and ethical reasons, including insufficient knowledge about possible risks to future generations[40] and higher risks versus SCGT.[41] The US has no federal controls specifically addressing human genetic modification (beyond FDA regulations for therapies in general).[40][42][43][44]

The delivery of DNA into cells can be accomplished by multiple methods. The two major classes are recombinant viruses (sometimes called biological nanoparticles or viral vectors) and naked DNA or DNA complexes (non-viral methods).

In order to replicate, viruses introduce their genetic material into the host cell, tricking the host’s cellular machinery into using it as blueprints for viral proteins. Retroviruses go a stage further by having their genetic material copied into the genome of the host cell. Scientists exploit this by substituting a virus’s genetic material with therapeutic DNA. (The term ‘DNA’ may be an oversimplification, as some viruses contain RNA, and gene therapy could take this form as well.) A number of viruses have been used for human gene therapy, including retroviruses, adenoviruses, herpes simplex, vaccinia, and adeno-associated virus.[4] Like the genetic material (DNA or RNA) in viruses, therapeutic DNA can be designed to simply serve as a temporary blueprint that is degraded naturally or (at least theoretically) to enter the host’s genome, becoming a permanent part of the host’s DNA in infected cells.

Non-viral methods present certain advantages over viral methods, such as large scale production and low host immunogenicity. However, non-viral methods initially produced lower levels of transfection and gene expression, and thus lower therapeutic efficacy. Later technology remedied this deficiency.[citation needed]

Methods for non-viral gene therapy include the injection of naked DNA, electroporation, the gene gun, sonoporation, magnetofection, the use of oligonucleotides, lipoplexes, dendrimers, and inorganic nanoparticles.

Some of the unsolved problems include:

Three patients’ deaths have been reported in gene therapy trials, putting the field under close scrutiny. The first was that of Jesse Gelsinger, who died in 1999 because of immune rejection response.[51] One X-SCID patient died of leukemia in 2003.[9] In 2007, a rheumatoid arthritis patient died from an infection; the subsequent investigation concluded that the death was not related to gene therapy.[52]

In 1972 Friedmann and Roblin authored a paper in Science titled “Gene therapy for human genetic disease?”[53] Rogers (1970) was cited for proposing that exogenous good DNA be used to replace the defective DNA in those who suffer from genetic defects.[54]

In 1984 a retrovirus vector system was designed that could efficiently insert foreign genes into mammalian chromosomes.[55]

The first approved gene therapy clinical research in the US took place on 14 September 1990, at the National Institutes of Health (NIH), under the direction of William French Anderson.[56] Four-year-old Ashanti DeSilva received treatment for a genetic defect that left her with ADA-SCID, a severe immune system deficiency. The defective gene of the patient’s blood cells was replaced by the functional variant. Ashantis immune system was partially restored by the therapy. Production of the missing enzyme was temporarily stimulated, but the new cells with functional genes were not generated. She led a normal life only with the regular injections performed every two months. The effects were successful, but temporary.[57]

Cancer gene therapy was introduced in 1992/93 (Trojan et al. 1993).[58] The treatment of glioblastoma multiforme, the malignant brain tumor whose outcome is always fatal, was done using a vector expressing antisense IGF-I RNA (clinical trial approved by NIH protocolno.1602 November 24, 1993,[59] and by the FDA in 1994). This therapy also represents the beginning of cancer immunogene therapy, a treatment which proves to be effective due to the anti-tumor mechanism of IGF-I antisense, which is related to strong immune and apoptotic phenomena.

In 1992 Claudio Bordignon, working at the Vita-Salute San Raffaele University, performed the first gene therapy procedure using hematopoietic stem cells as vectors to deliver genes intended to correct hereditary diseases.[60] In 2002 this work led to the publication of the first successful gene therapy treatment for adenosine deaminase deficiency (ADA-SCID). The success of a multi-center trial for treating children with SCID (severe combined immune deficiency or “bubble boy” disease) from 2000 and 2002, was questioned when two of the ten children treated at the trial’s Paris center developed a leukemia-like condition. Clinical trials were halted temporarily in 2002, but resumed after regulatory review of the protocol in the US, the United Kingdom, France, Italy, and Germany.[61]

In 1993 Andrew Gobea was born with SCID following prenatal genetic screening. Blood was removed from his mother’s placenta and umbilical cord immediately after birth, to acquire stem cells. The allele that codes for adenosine deaminase (ADA) was obtained and inserted into a retrovirus. Retroviruses and stem cells were mixed, after which the viruses inserted the gene into the stem cell chromosomes. Stem cells containing the working ADA gene were injected into Andrew’s blood. Injections of the ADA enzyme were also given weekly. For four years T cells (white blood cells), produced by stem cells, made ADA enzymes using the ADA gene. After four years more treatment was needed.[62]

Jesse Gelsinger’s death in 1999 impeded gene therapy research in the US.[63][64] As a result, the FDA suspended several clinical trials pending the reevaluation of ethical and procedural practices.[65]

The modified cancer gene therapy strategy of antisense IGF-I RNA (NIH n 1602)[59] using antisense / triple helix anti-IGF-I approach was registered in 2002 by Wiley gene therapy clinical trial – n 635 and 636. The approach has shown promising results in the treatment of six different malignant tumors: glioblastoma, cancers of liver, colon, prostate, uterus, and ovary (Collaborative NATO Science Programme on Gene Therapy USA, France, Poland n LST 980517 conducted by J. Trojan) (Trojan et al., 2012). This anti-gene antisense/triple helix therapy has proven to be efficient, due to the mechanism stopping simultaneously IGF-I expression on translation and transcription levels, strengthening anti-tumor immune and apoptotic phenomena.

Sickle-cell disease can be treated in mice.[66] The mice which have essentially the same defect that causes human cases used a viral vector to induce production of fetal hemoglobin (HbF), which normally ceases to be produced shortly after birth. In humans, the use of hydroxyurea to stimulate the production of HbF temporarily alleviates sickle cell symptoms. The researchers demonstrated this treatment to be a more permanent means to increase therapeutic HbF production.[67]

A new gene therapy approach repaired errors in messenger RNA derived from defective genes. This technique has the potential to treat thalassaemia, cystic fibrosis and some cancers.[68]

Researchers created liposomes 25 nanometers across that can carry therapeutic DNA through pores in the nuclear membrane.[69]

In 2003 a research team inserted genes into the brain for the first time. They used liposomes coated in a polymer called polyethylene glycol, which unlike viral vectors, are small enough to cross the bloodbrain barrier.[70]

Short pieces of double-stranded RNA (short, interfering RNAs or siRNAs) are used by cells to degrade RNA of a particular sequence. If a siRNA is designed to match the RNA copied from a faulty gene, then the abnormal protein product of that gene will not be produced.[71]

Gendicine is a cancer gene therapy that delivers the tumor suppressor gene p53 using an engineered adenovirus. In 2003, it was approved in China for the treatment of head and neck squamous cell carcinoma.[25]

In March researchers announced the successful use of gene therapy to treat two adult patients for X-linked chronic granulomatous disease, a disease which affects myeloid cells and damages the immune system. The study is the first to show that gene therapy can treat the myeloid system.[72]

In May a team reported a way to prevent the immune system from rejecting a newly delivered gene.[73] Similar to organ transplantation, gene therapy has been plagued by this problem. The immune system normally recognizes the new gene as foreign and rejects the cells carrying it. The research utilized a newly uncovered network of genes regulated by molecules known as microRNAs. This natural function selectively obscured their therapeutic gene in immune system cells and protected it from discovery. Mice infected with the gene containing an immune-cell microRNA target sequence did not reject the gene.

In August scientists successfully treated metastatic melanoma in two patients using killer T cells genetically retargeted to attack the cancer cells.[74]

In November researchers reported on the use of VRX496, a gene-based immunotherapy for the treatment of HIV that uses a lentiviral vector to deliver an antisense gene against the HIV envelope. In a phase I clinical trial, five subjects with chronic HIV infection who had failed to respond to at least two antiretroviral regimens were treated. A single intravenous infusion of autologous CD4 T cells genetically modified with VRX496 was well tolerated. All patients had stable or decreased viral load; four of the five patients had stable or increased CD4 T cell counts. All five patients had stable or increased immune response to HIV antigens and other pathogens. This was the first evaluation of a lentiviral vector administered in a US human clinical trial.[75][76]

In May researchers announced the first gene therapy trial for inherited retinal disease. The first operation was carried out on a 23-year-old British male, Robert Johnson, in early 2007.[77]

Leber’s congenital amaurosis is an inherited blinding disease caused by mutations in the RPE65 gene. The results of a small clinical trial in children were published in April.[11] Delivery of recombinant adeno-associated virus (AAV) carrying RPE65 yielded positive results. In May two more groups reported positive results in independent clinical trials using gene therapy to treat the condition. In all three clinical trials, patients recovered functional vision without apparent side-effects.[11][12][13][14]

In September researchers were able to give trichromatic vision to squirrel monkeys.[78] In November 2009, researchers halted a fatal genetic disorder called adrenoleukodystrophy in two children using a lentivirus vector to deliver a functioning version of ABCD1, the gene that is mutated in the disorder.[79]

An April paper reported that gene therapy addressed achromatopsia (color blindness) in dogs by targeting cone photoreceptors. Cone function and day vision were restored for at least 33 months in two young specimens. The therapy was less efficient for older dogs.[80]

In September it was announced that an 18-year-old male patient in France with beta-thalassemia major had been successfully treated.[81] Beta-thalassemia major is an inherited blood disease in which beta haemoglobin is missing and patients are dependent on regular lifelong blood transfusions.[82] The technique used a lentiviral vector to transduce the human -globin gene into purified blood and marrow cells obtained from the patient in June 2007.[83] The patient’s haemoglobin levels were stable at 9 to 10 g/dL. About a third of the hemoglobin contained the form introduced by the viral vector and blood transfusions were not needed.[83][84] Further clinical trials were planned.[85] Bone marrow transplants are the only cure for thalassemia, but 75% of patients do not find a matching donor.[84]

Cancer immunogene therapy using modified antigene, antisense/triple helix approach was introduced in South America in 2010/11 in La Sabana University, Bogota (Ethical Committee 14 December 2010, no P-004-10). Considering the ethical aspect of gene diagnostic and gene therapy targeting IGF-I, the IGF-I expressing tumors i.e. lung and epidermis cancers were treated (Trojan et al. 2016).[86][87]

In 2007 and 2008, a man (Timothy Ray Brown) was cured of HIV by repeated hematopoietic stem cell transplantation (see also allogeneic stem cell transplantation, allogeneic bone marrow transplantation, allotransplantation) with double-delta-32 mutation which disables the CCR5 receptor. This cure was accepted by the medical community in 2011.[88] It required complete ablation of existing bone marrow, which is very debilitating.

In August two of three subjects of a pilot study were confirmed to have been cured from chronic lymphocytic leukemia (CLL). The therapy used genetically modified T cells to attack cells that expressed the CD19 protein to fight the disease.[20] In 2013, the researchers announced that 26 of 59 patients had achieved complete remission and the original patient had remained tumor-free.[89]

Human HGF plasmid DNA therapy of cardiomyocytes is being examined as a potential treatment for coronary artery disease as well as treatment for the damage that occurs to the heart after myocardial infarction.[90][91]

In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia; it delivers the gene encoding for VEGF.[92][26] Neovasculogen is a plasmid encoding the CMV promoter and the 165 amino acid form of VEGF.[93][94]

The FDA approved Phase 1 clinical trials on thalassemia major patients in the US for 10 participants in July.[95] The study was expected to continue until 2015.[85]

In July 2012, the European Medicines Agency recommended approval of a gene therapy treatment for the first time in either Europe or the United States. The treatment used Alipogene tiparvovec (Glybera) to compensate for lipoprotein lipase deficiency, which can cause severe pancreatitis.[96] The recommendation was endorsed by the European Commission in November 2012[10][27][97][98] and commercial rollout began in late 2014.[99] Alipogene tiparvovec was expected to cost around $1.6 million per treatment in 2012,[100] revised to $1 million in 2015,[101] making it the most expensive medicine in the world at the time.[102] As of 2016[update], only one person had been treated with drug.[103]

In December 2012, it was reported that 10 of 13 patients with multiple myeloma were in remission “or very close to it” three months after being injected with a treatment involving genetically engineered T cells to target proteins NY-ESO-1 and LAGE-1, which exist only on cancerous myeloma cells.[22]

In March researchers reported that three of five adult subjects who had acute lymphocytic leukemia (ALL) had been in remission for five months to two years after being treated with genetically modified T cells which attacked cells with CD19 genes on their surface, i.e. all B-cells, cancerous or not. The researchers believed that the patients’ immune systems would make normal T-cells and B-cells after a couple of months. They were also given bone marrow. One patient relapsed and died and one died of a blood clot unrelated to the disease.[21]

Following encouraging Phase 1 trials, in April, researchers announced they were starting Phase 2 clinical trials (called CUPID2 and SERCA-LVAD) on 250 patients[104] at several hospitals to combat heart disease. The therapy was designed to increase the levels of SERCA2, a protein in heart muscles, improving muscle function.[105] The FDA granted this a Breakthrough Therapy Designation to accelerate the trial and approval process.[106] In 2016 it was reported that no improvement was found from the CUPID 2 trial.[107]

In July researchers reported promising results for six children with two severe hereditary diseases had been treated with a partially deactivated lentivirus to replace a faulty gene and after 732 months. Three of the children had metachromatic leukodystrophy, which causes children to lose cognitive and motor skills.[108] The other children had Wiskott-Aldrich syndrome, which leaves them to open to infection, autoimmune diseases, and cancer.[109] Follow up trials with gene therapy on another six children with Wiskott-Aldrich syndrome were also reported as promising.[110][111]

In October researchers reported that two children born with adenosine deaminase severe combined immunodeficiency disease (ADA-SCID) had been treated with genetically engineered stem cells 18 months previously and that their immune systems were showing signs of full recovery. Another three children were making progress.[18] In 2014 a further 18 children with ADA-SCID were cured by gene therapy.[112] ADA-SCID children have no functioning immune system and are sometimes known as “bubble children.”[18]

Also in October researchers reported that they had treated six hemophilia sufferers in early 2011 using an adeno-associated virus. Over two years later all six were producing clotting factor.[18][113]

In January researchers reported that six choroideremia patients had been treated with adeno-associated virus with a copy of REP1. Over a six-month to two-year period all had improved their sight.[114][115] By 2016, 32 patients had been treated with positive results and researchers were hopeful the treatment would be long-lasting.[15] Choroideremia is an inherited genetic eye disease with no approved treatment, leading to loss of sight.

In March researchers reported that 12 HIV patients had been treated since 2009 in a trial with a genetically engineered virus with a rare mutation (CCR5 deficiency) known to protect against HIV with promising results.[116][117]

Clinical trials of gene therapy for sickle cell disease were started in 2014.[118][119] There is a need for high quality randomised controlled trials assessing the risks and benefits involved with gene therapy for people with sickle cell disease.[120]

In February LentiGlobin BB305, a gene therapy treatment undergoing clinical trials for treatment of beta thalassemia gained FDA “breakthrough” status after several patients were able to forgo the frequent blood transfusions usually required to treat the disease.[121]

In March researchers delivered a recombinant gene encoding a broadly neutralizing antibody into monkeys infected with simian HIV; the monkeys’ cells produced the antibody, which cleared them of HIV. The technique is named immunoprophylaxis by gene transfer (IGT). Animal tests for antibodies to ebola, malaria, influenza, and hepatitis were underway.[122][123]

In March, scientists, including an inventor of CRISPR, Jennifer Doudna, urged a worldwide moratorium on germline gene therapy, writing “scientists should avoid even attempting, in lax jurisdictions, germline genome modification for clinical application in humans” until the full implications “are discussed among scientific and governmental organizations”.[124][125][126][127]

In October, researchers announced that they had treated a baby girl, Layla Richards, with an experimental treatment using donor T-cells genetically engineered using TALEN to attack cancer cells. One year after the treatment she was still free of her cancer (a highly aggressive form of acute lymphoblastic leukaemia [ALL]).[128] Children with highly aggressive ALL normally have a very poor prognosis and Layla’s disease had been regarded as terminal before the treatment.[129]

In December, scientists of major world academies called for a moratorium on inheritable human genome edits, including those related to CRISPR-Cas9 technologies[130] but that basic research including embryo gene editing should continue.[131]

In April the Committee for Medicinal Products for Human Use of the European Medicines Agency endorsed a gene therapy treatment called Strimvelis[132][133] and the European Commission approved it in June.[134] This treats children born with adenosine deaminase deficiency and who have no functioning immune system. This was the second gene therapy treatment to be approved in Europe.[135]

In October, Chinese scientists reported they had started a trial to genetically modify T-cells from 10 adult patients with lung cancer and reinject the modified T-cells back into their bodies to attack the cancer cells. The T-cells had the PD-1 protein (which stops or slows the immune response) removed using CRISPR-Cas9.[136][137]

A 2016 Cochrane systematic review looking at data from four trials on topical cystic fibrosis transmembrane conductance regulator (CFTR) gene therapy does not support its clinical use as a mist inhaled into the lungs to treat cystic fibrosis patients with lung infections. One of the four trials did find weak evidence that liposome-based CFTR gene transfer therapy may lead to a small respiratory improvement for people with CF. This weak evidence is not enough to make a clinical recommendation for routine CFTR gene therapy.[138]

In February Kite Pharma announced results from a clinical trial of CAR-T cells in around a hundred people with advanced Non-Hodgkin lymphoma.[139]

In March, French scientists reported on clinical research of gene therapy to treat sickle-cell disease.[140]

In August, the FDA approved tisagenlecleucel for acute lymphoblastic leukemia.[141] Tisagenlecleucel is an adoptive cell transfer therapy for B-cell acute lymphoblastic leukemia; T cells from a person with cancer are removed, genetically engineered to make a specific T-cell receptor (a chimeric T cell receptor, or “CAR-T”) that reacts to the cancer, and are administered back to the person. The T cells are engineered to target a protein called CD19 that is common on B cells. This is the first form of gene therapy to be approved in the United States. In October, a similar therapy called axicabtagene ciloleucel was approved for non-Hodgkin lymphoma.[142]

In December the results of using an adeno-associated virus with blood clotting factor VIII to treat nine haemophilia A patients were published. Six of the seven patients on the high dose regime increased the level of the blood clotting VIII to normal levels. The low and medium dose regimes had no effect on the patient’s blood clotting levels.[143][144]

In December, the FDA approved Luxturna, the first in vivo gene therapy, for the treatment of blindness due to Leber’s congenital amaurosis.[145] The price of this treatment was 850,000 US dollars for both eyes.[146][147]

Speculated uses for gene therapy include:

Gene therapy techniques have the potential to provide alternative treatments for those with infertility. Recently, successful experimentation on mice has proven that fertility can be restored by using the gene therapy method, CRISPR.[148] Spermatogenical stem cells from another organism were transplanted into the testes of an infertile male mouse. The stem cells re-established spermatogenesis and fertility.[149]

Athletes might adopt gene therapy technologies to improve their performance.[150] Gene doping is not known to occur, but multiple gene therapies may have such effects. Kayser et al. argue that gene doping could level the playing field if all athletes receive equal access. Critics claim that any therapeutic intervention for non-therapeutic/enhancement purposes compromises the ethical foundations of medicine and sports.[151]

Genetic engineering could be used to cure diseases, but also to change physical appearance, metabolism, and even improve physical capabilities and mental faculties such as memory and intelligence. Ethical claims about germline engineering include beliefs that every fetus has a right to remain genetically unmodified, that parents hold the right to genetically modify their offspring, and that every child has the right to be born free of preventable diseases.[152][153][154] For parents, genetic engineering could be seen as another child enhancement technique to add to diet, exercise, education, training, cosmetics, and plastic surgery.[155][156] Another theorist claims that moral concerns limit but do not prohibit germline engineering.[157]

Possible regulatory schemes include a complete ban, provision to everyone, or professional self-regulation. The American Medical Associations Council on Ethical and Judicial Affairs stated that “genetic interventions to enhance traits should be considered permissible only in severely restricted situations: (1) clear and meaningful benefits to the fetus or child; (2) no trade-off with other characteristics or traits; and (3) equal access to the genetic technology, irrespective of income or other socioeconomic characteristics.”[158]

As early in the history of biotechnology as 1990, there have been scientists opposed to attempts to modify the human germline using these new tools,[159] and such concerns have continued as technology progressed.[160][161] With the advent of new techniques like CRISPR, in March 2015 a group of scientists urged a worldwide moratorium on clinical use of gene editing technologies to edit the human genome in a way that can be inherited.[124][125][126][127] In April 2015, researchers sparked controversy when they reported results of basic research to edit the DNA of non-viable human embryos using CRISPR.[148][162] A committee of the American National Academy of Sciences and National Academy of Medicine gave qualified support to human genome editing in 2017[163][164] once answers have been found to safety and efficiency problems “but only for serious conditions under stringent oversight.”[165]

Regulations covering genetic modification are part of general guidelines about human-involved biomedical research. There are no international treaties which are legally binding in this area, but there are recommendations for national laws from various bodies.

The Helsinki Declaration (Ethical Principles for Medical Research Involving Human Subjects) was amended by the World Medical Association’s General Assembly in 2008. This document provides principles physicians and researchers must consider when involving humans as research subjects. The Statement on Gene Therapy Research initiated by the Human Genome Organization (HUGO) in 2001 provides a legal baseline for all countries. HUGOs document emphasizes human freedom and adherence to human rights, and offers recommendations for somatic gene therapy, including the importance of recognizing public concerns about such research.[166]

No federal legislation lays out protocols or restrictions about human genetic engineering. This subject is governed by overlapping regulations from local and federal agencies, including the Department of Health and Human Services, the FDA and NIH’s Recombinant DNA Advisory Committee. Researchers seeking federal funds for an investigational new drug application, (commonly the case for somatic human genetic engineering,) must obey international and federal guidelines for the protection of human subjects.[167]

NIH serves as the main gene therapy regulator for federally funded research. Privately funded research is advised to follow these regulations. NIH provides funding for research that develops or enhances genetic engineering techniques and to evaluate the ethics and quality in current research. The NIH maintains a mandatory registry of human genetic engineering research protocols that includes all federally funded projects.

An NIH advisory committee published a set of guidelines on gene manipulation.[168] The guidelines discuss lab safety as well as human test subjects and various experimental types that involve genetic changes. Several sections specifically pertain to human genetic engineering, including Section III-C-1. This section describes required review processes and other aspects when seeking approval to begin clinical research involving genetic transfer into a human patient.[169] The protocol for a gene therapy clinical trial must be approved by the NIH’s Recombinant DNA Advisory Committee prior to any clinical trial beginning; this is different from any other kind of clinical trial.[168]

As with other kinds of drugs, the FDA regulates the quality and safety of gene therapy products and supervises how these products are used clinically. Therapeutic alteration of the human genome falls under the same regulatory requirements as any other medical treatment. Research involving human subjects, such as clinical trials, must be reviewed and approved by the FDA and an Institutional Review Board.[170][171]

Gene therapy is the basis for the plotline of the film I Am Legend[172] and the TV show Will Gene Therapy Change the Human Race?.[173] In 1994, gene therapy was a plot element in The Erlenmeyer Flask, The X-Files’ first-season finale. It is also used in Stargate as a means of allowing humans to use Ancient technology.[174]

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Gene therapy – Wikipedia

Gene therapy – Wikipedia

In the medicine field, gene therapy (also called human gene transfer) is the therapeutic delivery of nucleic acid into a patient’s cells as a drug to treat disease.[1][2] The first attempt at modifying human DNA was performed in 1980 by Martin Cline, but the first successful nuclear gene transfer in humans, approved by the National Institutes of Health, was performed in May 1989.[3] The first therapeutic use of gene transfer as well as the first direct insertion of human DNA into the nuclear genome was performed by French Anderson in a trial starting in September 1990.

Between 1989 and February 2016, over 2,300 clinical trials had been conducted, more than half of them in phase I.[4]

Not all medical procedures that introduce alterations to a patient’s genetic makeup can be considered gene therapy. Bone marrow transplantation and organ transplants in general have been found to introduce foreign DNA into patients.[5] Gene therapy is defined by the precision of the procedure and the intention of direct therapeutic effect.

Gene therapy was conceptualized in 1972, by authors who urged caution before commencing human gene therapy studies.

The first attempt, an unsuccessful one, at gene therapy (as well as the first case of medical transfer of foreign genes into humans not counting organ transplantation) was performed by Martin Cline on 10 July 1980.[6][7] Cline claimed that one of the genes in his patients was active six months later, though he never published this data or had it verified[8] and even if he is correct, it’s unlikely it produced any significant beneficial effects treating beta-thalassemia.

After extensive research on animals throughout the 1980s and a 1989 bacterial gene tagging trial on humans, the first gene therapy widely accepted as a success was demonstrated in a trial that started on 14 September 1990, when Ashi DeSilva was treated for ADA-SCID.[9]

The first somatic treatment that produced a permanent genetic change was performed in 1993.[citation needed]

Gene therapy is a way to fix a genetic problem at its source. The polymers are either translated into proteins, interfere with target gene expression, or possibly correct genetic mutations.

The most common form uses DNA that encodes a functional, therapeutic gene to replace a mutated gene. The polymer molecule is packaged within a “vector”, which carries the molecule inside cells.

Early clinical failures led to dismissals of gene therapy. Clinical successes since 2006 regained researchers’ attention, although as of 2014[update], it was still largely an experimental technique.[10] These include treatment of retinal diseases Leber’s congenital amaurosis[11][12][13][14] and choroideremia,[15] X-linked SCID,[16] ADA-SCID,[17][18] adrenoleukodystrophy,[19] chronic lymphocytic leukemia (CLL),[20] acute lymphocytic leukemia (ALL),[21] multiple myeloma,[22] haemophilia,[18] and Parkinson’s disease.[23] Between 2013 and April 2014, US companies invested over $600 million in the field.[24]

The first commercial gene therapy, Gendicine, was approved in China in 2003 for the treatment of certain cancers.[25] In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia.[26]In 2012 Glybera, a treatment for a rare inherited disorder, became the first treatment to be approved for clinical use in either Europe or the United States after its endorsement by the European Commission.[10][27]

Following early advances in genetic engineering of bacteria, cells, and small animals, scientists started considering how to apply it to medicine. Two main approaches were considered replacing or disrupting defective genes.[28] Scientists focused on diseases caused by single-gene defects, such as cystic fibrosis, haemophilia, muscular dystrophy, thalassemia, and sickle cell anemia. Glybera treats one such disease, caused by a defect in lipoprotein lipase.[27]

DNA must be administered, reach the damaged cells, enter the cell and either express or disrupt a protein.[29] Multiple delivery techniques have been explored. The initial approach incorporated DNA into an engineered virus to deliver the DNA into a chromosome.[30][31] Naked DNA approaches have also been explored, especially in the context of vaccine development.[32]

Generally, efforts focused on administering a gene that causes a needed protein to be expressed. More recently, increased understanding of nuclease function has led to more direct DNA editing, using techniques such as zinc finger nucleases and CRISPR. The vector incorporates genes into chromosomes. The expressed nucleases then knock out and replace genes in the chromosome. As of 2014[update] these approaches involve removing cells from patients, editing a chromosome and returning the transformed cells to patients.[33]

Gene editing is a potential approach to alter the human genome to treat genetic diseases,[34] viral diseases,[35] and cancer.[36] As of 2016[update] these approaches were still years from being medicine.[37][38]

Gene therapy may be classified into two types:

In somatic cell gene therapy (SCGT), the therapeutic genes are transferred into any cell other than a gamete, germ cell, gametocyte, or undifferentiated stem cell. Any such modifications affect the individual patient only, and are not inherited by offspring. Somatic gene therapy represents mainstream basic and clinical research, in which therapeutic DNA (either integrated in the genome or as an external episome or plasmid) is used to treat disease.

Over 600 clinical trials utilizing SCGT are underway[when?] in the US. Most focus on severe genetic disorders, including immunodeficiencies, haemophilia, thalassaemia, and cystic fibrosis. Such single gene disorders are good candidates for somatic cell therapy. The complete correction of a genetic disorder or the replacement of multiple genes is not yet possible. Only a few of the trials are in the advanced stages.[39]

In germline gene therapy (GGT), germ cells (sperm or egg cells) are modified by the introduction of functional genes into their genomes. Modifying a germ cell causes all the organism’s cells to contain the modified gene. The change is therefore heritable and passed on to later generations. Australia, Canada, Germany, Israel, Switzerland, and the Netherlands[40] prohibit GGT for application in human beings, for technical and ethical reasons, including insufficient knowledge about possible risks to future generations[40] and higher risks versus SCGT.[41] The US has no federal controls specifically addressing human genetic modification (beyond FDA regulations for therapies in general).[40][42][43][44]

The delivery of DNA into cells can be accomplished by multiple methods. The two major classes are recombinant viruses (sometimes called biological nanoparticles or viral vectors) and naked DNA or DNA complexes (non-viral methods).

In order to replicate, viruses introduce their genetic material into the host cell, tricking the host’s cellular machinery into using it as blueprints for viral proteins. Retroviruses go a stage further by having their genetic material copied into the genome of the host cell. Scientists exploit this by substituting a virus’s genetic material with therapeutic DNA. (The term ‘DNA’ may be an oversimplification, as some viruses contain RNA, and gene therapy could take this form as well.) A number of viruses have been used for human gene therapy, including retroviruses, adenoviruses, herpes simplex, vaccinia, and adeno-associated virus.[4] Like the genetic material (DNA or RNA) in viruses, therapeutic DNA can be designed to simply serve as a temporary blueprint that is degraded naturally or (at least theoretically) to enter the host’s genome, becoming a permanent part of the host’s DNA in infected cells.

Non-viral methods present certain advantages over viral methods, such as large scale production and low host immunogenicity. However, non-viral methods initially produced lower levels of transfection and gene expression, and thus lower therapeutic efficacy. Later technology remedied this deficiency.[citation needed]

Methods for non-viral gene therapy include the injection of naked DNA, electroporation, the gene gun, sonoporation, magnetofection, the use of oligonucleotides, lipoplexes, dendrimers, and inorganic nanoparticles.

Some of the unsolved problems include:

Three patients’ deaths have been reported in gene therapy trials, putting the field under close scrutiny. The first was that of Jesse Gelsinger, who died in 1999 because of immune rejection response.[51] One X-SCID patient died of leukemia in 2003.[9] In 2007, a rheumatoid arthritis patient died from an infection; the subsequent investigation concluded that the death was not related to gene therapy.[52]

In 1972 Friedmann and Roblin authored a paper in Science titled “Gene therapy for human genetic disease?”[53] Rogers (1970) was cited for proposing that exogenous good DNA be used to replace the defective DNA in those who suffer from genetic defects.[54]

In 1984 a retrovirus vector system was designed that could efficiently insert foreign genes into mammalian chromosomes.[55]

The first approved gene therapy clinical research in the US took place on 14 September 1990, at the National Institutes of Health (NIH), under the direction of William French Anderson.[56] Four-year-old Ashanti DeSilva received treatment for a genetic defect that left her with ADA-SCID, a severe immune system deficiency. The defective gene of the patient’s blood cells was replaced by the functional variant. Ashantis immune system was partially restored by the therapy. Production of the missing enzyme was temporarily stimulated, but the new cells with functional genes were not generated. She led a normal life only with the regular injections performed every two months. The effects were successful, but temporary.[57]

Cancer gene therapy was introduced in 1992/93 (Trojan et al. 1993).[58] The treatment of glioblastoma multiforme, the malignant brain tumor whose outcome is always fatal, was done using a vector expressing antisense IGF-I RNA (clinical trial approved by NIH protocolno.1602 November 24, 1993,[59] and by the FDA in 1994). This therapy also represents the beginning of cancer immunogene therapy, a treatment which proves to be effective due to the anti-tumor mechanism of IGF-I antisense, which is related to strong immune and apoptotic phenomena.

In 1992 Claudio Bordignon, working at the Vita-Salute San Raffaele University, performed the first gene therapy procedure using hematopoietic stem cells as vectors to deliver genes intended to correct hereditary diseases.[60] In 2002 this work led to the publication of the first successful gene therapy treatment for adenosine deaminase deficiency (ADA-SCID). The success of a multi-center trial for treating children with SCID (severe combined immune deficiency or “bubble boy” disease) from 2000 and 2002, was questioned when two of the ten children treated at the trial’s Paris center developed a leukemia-like condition. Clinical trials were halted temporarily in 2002, but resumed after regulatory review of the protocol in the US, the United Kingdom, France, Italy, and Germany.[61]

In 1993 Andrew Gobea was born with SCID following prenatal genetic screening. Blood was removed from his mother’s placenta and umbilical cord immediately after birth, to acquire stem cells. The allele that codes for adenosine deaminase (ADA) was obtained and inserted into a retrovirus. Retroviruses and stem cells were mixed, after which the viruses inserted the gene into the stem cell chromosomes. Stem cells containing the working ADA gene were injected into Andrew’s blood. Injections of the ADA enzyme were also given weekly. For four years T cells (white blood cells), produced by stem cells, made ADA enzymes using the ADA gene. After four years more treatment was needed.[62]

Jesse Gelsinger’s death in 1999 impeded gene therapy research in the US.[63][64] As a result, the FDA suspended several clinical trials pending the reevaluation of ethical and procedural practices.[65]

The modified cancer gene therapy strategy of antisense IGF-I RNA (NIH n 1602)[59] using antisense / triple helix anti-IGF-I approach was registered in 2002 by Wiley gene therapy clinical trial – n 635 and 636. The approach has shown promising results in the treatment of six different malignant tumors: glioblastoma, cancers of liver, colon, prostate, uterus, and ovary (Collaborative NATO Science Programme on Gene Therapy USA, France, Poland n LST 980517 conducted by J. Trojan) (Trojan et al., 2012). This anti-gene antisense/triple helix therapy has proven to be efficient, due to the mechanism stopping simultaneously IGF-I expression on translation and transcription levels, strengthening anti-tumor immune and apoptotic phenomena.

Sickle-cell disease can be treated in mice.[66] The mice which have essentially the same defect that causes human cases used a viral vector to induce production of fetal hemoglobin (HbF), which normally ceases to be produced shortly after birth. In humans, the use of hydroxyurea to stimulate the production of HbF temporarily alleviates sickle cell symptoms. The researchers demonstrated this treatment to be a more permanent means to increase therapeutic HbF production.[67]

A new gene therapy approach repaired errors in messenger RNA derived from defective genes. This technique has the potential to treat thalassaemia, cystic fibrosis and some cancers.[68]

Researchers created liposomes 25 nanometers across that can carry therapeutic DNA through pores in the nuclear membrane.[69]

In 2003 a research team inserted genes into the brain for the first time. They used liposomes coated in a polymer called polyethylene glycol, which unlike viral vectors, are small enough to cross the bloodbrain barrier.[70]

Short pieces of double-stranded RNA (short, interfering RNAs or siRNAs) are used by cells to degrade RNA of a particular sequence. If a siRNA is designed to match the RNA copied from a faulty gene, then the abnormal protein product of that gene will not be produced.[71]

Gendicine is a cancer gene therapy that delivers the tumor suppressor gene p53 using an engineered adenovirus. In 2003, it was approved in China for the treatment of head and neck squamous cell carcinoma.[25]

In March researchers announced the successful use of gene therapy to treat two adult patients for X-linked chronic granulomatous disease, a disease which affects myeloid cells and damages the immune system. The study is the first to show that gene therapy can treat the myeloid system.[72]

In May a team reported a way to prevent the immune system from rejecting a newly delivered gene.[73] Similar to organ transplantation, gene therapy has been plagued by this problem. The immune system normally recognizes the new gene as foreign and rejects the cells carrying it. The research utilized a newly uncovered network of genes regulated by molecules known as microRNAs. This natural function selectively obscured their therapeutic gene in immune system cells and protected it from discovery. Mice infected with the gene containing an immune-cell microRNA target sequence did not reject the gene.

In August scientists successfully treated metastatic melanoma in two patients using killer T cells genetically retargeted to attack the cancer cells.[74]

In November researchers reported on the use of VRX496, a gene-based immunotherapy for the treatment of HIV that uses a lentiviral vector to deliver an antisense gene against the HIV envelope. In a phase I clinical trial, five subjects with chronic HIV infection who had failed to respond to at least two antiretroviral regimens were treated. A single intravenous infusion of autologous CD4 T cells genetically modified with VRX496 was well tolerated. All patients had stable or decreased viral load; four of the five patients had stable or increased CD4 T cell counts. All five patients had stable or increased immune response to HIV antigens and other pathogens. This was the first evaluation of a lentiviral vector administered in a US human clinical trial.[75][76]

In May researchers announced the first gene therapy trial for inherited retinal disease. The first operation was carried out on a 23-year-old British male, Robert Johnson, in early 2007.[77]

Leber’s congenital amaurosis is an inherited blinding disease caused by mutations in the RPE65 gene. The results of a small clinical trial in children were published in April.[11] Delivery of recombinant adeno-associated virus (AAV) carrying RPE65 yielded positive results. In May two more groups reported positive results in independent clinical trials using gene therapy to treat the condition. In all three clinical trials, patients recovered functional vision without apparent side-effects.[11][12][13][14]

In September researchers were able to give trichromatic vision to squirrel monkeys.[78] In November 2009, researchers halted a fatal genetic disorder called adrenoleukodystrophy in two children using a lentivirus vector to deliver a functioning version of ABCD1, the gene that is mutated in the disorder.[79]

An April paper reported that gene therapy addressed achromatopsia (color blindness) in dogs by targeting cone photoreceptors. Cone function and day vision were restored for at least 33 months in two young specimens. The therapy was less efficient for older dogs.[80]

In September it was announced that an 18-year-old male patient in France with beta-thalassemia major had been successfully treated.[81] Beta-thalassemia major is an inherited blood disease in which beta haemoglobin is missing and patients are dependent on regular lifelong blood transfusions.[82] The technique used a lentiviral vector to transduce the human -globin gene into purified blood and marrow cells obtained from the patient in June 2007.[83] The patient’s haemoglobin levels were stable at 9 to 10 g/dL. About a third of the hemoglobin contained the form introduced by the viral vector and blood transfusions were not needed.[83][84] Further clinical trials were planned.[85] Bone marrow transplants are the only cure for thalassemia, but 75% of patients do not find a matching donor.[84]

Cancer immunogene therapy using modified antigene, antisense/triple helix approach was introduced in South America in 2010/11 in La Sabana University, Bogota (Ethical Committee 14 December 2010, no P-004-10). Considering the ethical aspect of gene diagnostic and gene therapy targeting IGF-I, the IGF-I expressing tumors i.e. lung and epidermis cancers were treated (Trojan et al. 2016).[86][87]

In 2007 and 2008, a man (Timothy Ray Brown) was cured of HIV by repeated hematopoietic stem cell transplantation (see also allogeneic stem cell transplantation, allogeneic bone marrow transplantation, allotransplantation) with double-delta-32 mutation which disables the CCR5 receptor. This cure was accepted by the medical community in 2011.[88] It required complete ablation of existing bone marrow, which is very debilitating.

In August two of three subjects of a pilot study were confirmed to have been cured from chronic lymphocytic leukemia (CLL). The therapy used genetically modified T cells to attack cells that expressed the CD19 protein to fight the disease.[20] In 2013, the researchers announced that 26 of 59 patients had achieved complete remission and the original patient had remained tumor-free.[89]

Human HGF plasmid DNA therapy of cardiomyocytes is being examined as a potential treatment for coronary artery disease as well as treatment for the damage that occurs to the heart after myocardial infarction.[90][91]

In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia; it delivers the gene encoding for VEGF.[92][26] Neovasculogen is a plasmid encoding the CMV promoter and the 165 amino acid form of VEGF.[93][94]

The FDA approved Phase 1 clinical trials on thalassemia major patients in the US for 10 participants in July.[95] The study was expected to continue until 2015.[85]

In July 2012, the European Medicines Agency recommended approval of a gene therapy treatment for the first time in either Europe or the United States. The treatment used Alipogene tiparvovec (Glybera) to compensate for lipoprotein lipase deficiency, which can cause severe pancreatitis.[96] The recommendation was endorsed by the European Commission in November 2012[10][27][97][98] and commercial rollout began in late 2014.[99] Alipogene tiparvovec was expected to cost around $1.6 million per treatment in 2012,[100] revised to $1 million in 2015,[101] making it the most expensive medicine in the world at the time.[102] As of 2016[update], only one person had been treated with drug.[103]

In December 2012, it was reported that 10 of 13 patients with multiple myeloma were in remission “or very close to it” three months after being injected with a treatment involving genetically engineered T cells to target proteins NY-ESO-1 and LAGE-1, which exist only on cancerous myeloma cells.[22]

In March researchers reported that three of five adult subjects who had acute lymphocytic leukemia (ALL) had been in remission for five months to two years after being treated with genetically modified T cells which attacked cells with CD19 genes on their surface, i.e. all B-cells, cancerous or not. The researchers believed that the patients’ immune systems would make normal T-cells and B-cells after a couple of months. They were also given bone marrow. One patient relapsed and died and one died of a blood clot unrelated to the disease.[21]

Following encouraging Phase 1 trials, in April, researchers announced they were starting Phase 2 clinical trials (called CUPID2 and SERCA-LVAD) on 250 patients[104] at several hospitals to combat heart disease. The therapy was designed to increase the levels of SERCA2, a protein in heart muscles, improving muscle function.[105] The FDA granted this a Breakthrough Therapy Designation to accelerate the trial and approval process.[106] In 2016 it was reported that no improvement was found from the CUPID 2 trial.[107]

In July researchers reported promising results for six children with two severe hereditary diseases had been treated with a partially deactivated lentivirus to replace a faulty gene and after 732 months. Three of the children had metachromatic leukodystrophy, which causes children to lose cognitive and motor skills.[108] The other children had Wiskott-Aldrich syndrome, which leaves them to open to infection, autoimmune diseases, and cancer.[109] Follow up trials with gene therapy on another six children with Wiskott-Aldrich syndrome were also reported as promising.[110][111]

In October researchers reported that two children born with adenosine deaminase severe combined immunodeficiency disease (ADA-SCID) had been treated with genetically engineered stem cells 18 months previously and that their immune systems were showing signs of full recovery. Another three children were making progress.[18] In 2014 a further 18 children with ADA-SCID were cured by gene therapy.[112] ADA-SCID children have no functioning immune system and are sometimes known as “bubble children.”[18]

Also in October researchers reported that they had treated six hemophilia sufferers in early 2011 using an adeno-associated virus. Over two years later all six were producing clotting factor.[18][113]

In January researchers reported that six choroideremia patients had been treated with adeno-associated virus with a copy of REP1. Over a six-month to two-year period all had improved their sight.[114][115] By 2016, 32 patients had been treated with positive results and researchers were hopeful the treatment would be long-lasting.[15] Choroideremia is an inherited genetic eye disease with no approved treatment, leading to loss of sight.

In March researchers reported that 12 HIV patients had been treated since 2009 in a trial with a genetically engineered virus with a rare mutation (CCR5 deficiency) known to protect against HIV with promising results.[116][117]

Clinical trials of gene therapy for sickle cell disease were started in 2014.[118][119] There is a need for high quality randomised controlled trials assessing the risks and benefits involved with gene therapy for people with sickle cell disease.[120]

In February LentiGlobin BB305, a gene therapy treatment undergoing clinical trials for treatment of beta thalassemia gained FDA “breakthrough” status after several patients were able to forgo the frequent blood transfusions usually required to treat the disease.[121]

In March researchers delivered a recombinant gene encoding a broadly neutralizing antibody into monkeys infected with simian HIV; the monkeys’ cells produced the antibody, which cleared them of HIV. The technique is named immunoprophylaxis by gene transfer (IGT). Animal tests for antibodies to ebola, malaria, influenza, and hepatitis were underway.[122][123]

In March, scientists, including an inventor of CRISPR, Jennifer Doudna, urged a worldwide moratorium on germline gene therapy, writing “scientists should avoid even attempting, in lax jurisdictions, germline genome modification for clinical application in humans” until the full implications “are discussed among scientific and governmental organizations”.[124][125][126][127]

In October, researchers announced that they had treated a baby girl, Layla Richards, with an experimental treatment using donor T-cells genetically engineered using TALEN to attack cancer cells. One year after the treatment she was still free of her cancer (a highly aggressive form of acute lymphoblastic leukaemia [ALL]).[128] Children with highly aggressive ALL normally have a very poor prognosis and Layla’s disease had been regarded as terminal before the treatment.[129]

In December, scientists of major world academies called for a moratorium on inheritable human genome edits, including those related to CRISPR-Cas9 technologies[130] but that basic research including embryo gene editing should continue.[131]

In April the Committee for Medicinal Products for Human Use of the European Medicines Agency endorsed a gene therapy treatment called Strimvelis[132][133] and the European Commission approved it in June.[134] This treats children born with adenosine deaminase deficiency and who have no functioning immune system. This was the second gene therapy treatment to be approved in Europe.[135]

In October, Chinese scientists reported they had started a trial to genetically modify T-cells from 10 adult patients with lung cancer and reinject the modified T-cells back into their bodies to attack the cancer cells. The T-cells had the PD-1 protein (which stops or slows the immune response) removed using CRISPR-Cas9.[136][137]

A 2016 Cochrane systematic review looking at data from four trials on topical cystic fibrosis transmembrane conductance regulator (CFTR) gene therapy does not support its clinical use as a mist inhaled into the lungs to treat cystic fibrosis patients with lung infections. One of the four trials did find weak evidence that liposome-based CFTR gene transfer therapy may lead to a small respiratory improvement for people with CF. This weak evidence is not enough to make a clinical recommendation for routine CFTR gene therapy.[138]

In February Kite Pharma announced results from a clinical trial of CAR-T cells in around a hundred people with advanced Non-Hodgkin lymphoma.[139]

In March, French scientists reported on clinical research of gene therapy to treat sickle-cell disease.[140]

In August, the FDA approved tisagenlecleucel for acute lymphoblastic leukemia.[141] Tisagenlecleucel is an adoptive cell transfer therapy for B-cell acute lymphoblastic leukemia; T cells from a person with cancer are removed, genetically engineered to make a specific T-cell receptor (a chimeric T cell receptor, or “CAR-T”) that reacts to the cancer, and are administered back to the person. The T cells are engineered to target a protein called CD19 that is common on B cells. This is the first form of gene therapy to be approved in the United States. In October, a similar therapy called axicabtagene ciloleucel was approved for non-Hodgkin lymphoma.[142]

In December the results of using an adeno-associated virus with blood clotting factor VIII to treat nine haemophilia A patients were published. Six of the seven patients on the high dose regime increased the level of the blood clotting VIII to normal levels. The low and medium dose regimes had no effect on the patient’s blood clotting levels.[143][144]

In December, the FDA approved Luxturna, the first in vivo gene therapy, for the treatment of blindness due to Leber’s congenital amaurosis.[145] The price of this treatment was 850,000 US dollars for both eyes.[146][147]

Speculated uses for gene therapy include:

Gene therapy techniques have the potential to provide alternative treatments for those with infertility. Recently, successful experimentation on mice has proven that fertility can be restored by using the gene therapy method, CRISPR.[148] Spermatogenical stem cells from another organism were transplanted into the testes of an infertile male mouse. The stem cells re-established spermatogenesis and fertility.[149]

Athletes might adopt gene therapy technologies to improve their performance.[150] Gene doping is not known to occur, but multiple gene therapies may have such effects. Kayser et al. argue that gene doping could level the playing field if all athletes receive equal access. Critics claim that any therapeutic intervention for non-therapeutic/enhancement purposes compromises the ethical foundations of medicine and sports.[151]

Genetic engineering could be used to cure diseases, but also to change physical appearance, metabolism, and even improve physical capabilities and mental faculties such as memory and intelligence. Ethical claims about germline engineering include beliefs that every fetus has a right to remain genetically unmodified, that parents hold the right to genetically modify their offspring, and that every child has the right to be born free of preventable diseases.[152][153][154] For parents, genetic engineering could be seen as another child enhancement technique to add to diet, exercise, education, training, cosmetics, and plastic surgery.[155][156] Another theorist claims that moral concerns limit but do not prohibit germline engineering.[157]

Possible regulatory schemes include a complete ban, provision to everyone, or professional self-regulation. The American Medical Associations Council on Ethical and Judicial Affairs stated that “genetic interventions to enhance traits should be considered permissible only in severely restricted situations: (1) clear and meaningful benefits to the fetus or child; (2) no trade-off with other characteristics or traits; and (3) equal access to the genetic technology, irrespective of income or other socioeconomic characteristics.”[158]

As early in the history of biotechnology as 1990, there have been scientists opposed to attempts to modify the human germline using these new tools,[159] and such concerns have continued as technology progressed.[160][161] With the advent of new techniques like CRISPR, in March 2015 a group of scientists urged a worldwide moratorium on clinical use of gene editing technologies to edit the human genome in a way that can be inherited.[124][125][126][127] In April 2015, researchers sparked controversy when they reported results of basic research to edit the DNA of non-viable human embryos using CRISPR.[148][162] A committee of the American National Academy of Sciences and National Academy of Medicine gave qualified support to human genome editing in 2017[163][164] once answers have been found to safety and efficiency problems “but only for serious conditions under stringent oversight.”[165]

Regulations covering genetic modification are part of general guidelines about human-involved biomedical research. There are no international treaties which are legally binding in this area, but there are recommendations for national laws from various bodies.

The Helsinki Declaration (Ethical Principles for Medical Research Involving Human Subjects) was amended by the World Medical Association’s General Assembly in 2008. This document provides principles physicians and researchers must consider when involving humans as research subjects. The Statement on Gene Therapy Research initiated by the Human Genome Organization (HUGO) in 2001 provides a legal baseline for all countries. HUGOs document emphasizes human freedom and adherence to human rights, and offers recommendations for somatic gene therapy, including the importance of recognizing public concerns about such research.[166]

No federal legislation lays out protocols or restrictions about human genetic engineering. This subject is governed by overlapping regulations from local and federal agencies, including the Department of Health and Human Services, the FDA and NIH’s Recombinant DNA Advisory Committee. Researchers seeking federal funds for an investigational new drug application, (commonly the case for somatic human genetic engineering,) must obey international and federal guidelines for the protection of human subjects.[167]

NIH serves as the main gene therapy regulator for federally funded research. Privately funded research is advised to follow these regulations. NIH provides funding for research that develops or enhances genetic engineering techniques and to evaluate the ethics and quality in current research. The NIH maintains a mandatory registry of human genetic engineering research protocols that includes all federally funded projects.

An NIH advisory committee published a set of guidelines on gene manipulation.[168] The guidelines discuss lab safety as well as human test subjects and various experimental types that involve genetic changes. Several sections specifically pertain to human genetic engineering, including Section III-C-1. This section describes required review processes and other aspects when seeking approval to begin clinical research involving genetic transfer into a human patient.[169] The protocol for a gene therapy clinical trial must be approved by the NIH’s Recombinant DNA Advisory Committee prior to any clinical trial beginning; this is different from any other kind of clinical trial.[168]

As with other kinds of drugs, the FDA regulates the quality and safety of gene therapy products and supervises how these products are used clinically. Therapeutic alteration of the human genome falls under the same regulatory requirements as any other medical treatment. Research involving human subjects, such as clinical trials, must be reviewed and approved by the FDA and an Institutional Review Board.[170][171]

Gene therapy is the basis for the plotline of the film I Am Legend[172] and the TV show Will Gene Therapy Change the Human Race?.[173] In 1994, gene therapy was a plot element in The Erlenmeyer Flask, The X-Files’ first-season finale. It is also used in Stargate as a means of allowing humans to use Ancient technology.[174]

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Gene therapy – Wikipedia

Gene Therapy The Future of Medicine? | Science Care

Gene therapy is an experimental method of fighting disease that involves correcting or replacing a persons mutated or malfunctioning genes. This promising research is now being used in clinical trials and may lead to improved health outcomes for patients with inherited bleeding and immune disorders as well as some forms of blood cancer and other diseases.

What Is Gene Therapy?

Genes carry the DNA information needed to make proteins that are the building blocks of the human body. Some of these genes can become damaged through mutation, which can lead to disease conditions. Gene therapy is a scientific technique that uses genes to prevent or treat disease in a number of different ways:

Finding the Keys to Alter Body Chemistry

Currently, gene therapy can be used for conditions in which a change in the genetic coding of somatic cells can alter the course of a disease. For example, to correct a disease in which a specific enzyme is missing, the addition of a necessary gene component for production of the enzyme would fix the underlying problem of the disease. In many cases, harmless viruses are employed to serve as packets to carry the new gene to where it is needed. When used this way, the viruses are called vectors, and their own genes may be removed and replaced with the working human gene. Once the gene is correctly placed, it can be switched on to provide the working instructions for correct function.

Conditions Being Treated with Gene Therapy

Although much of this may still sound like the realm of mad scientists tinkering with the human body, gene therapy is an accepted experimental technique that is currently being used to help patients with certain types of cancer to target specific antibodies that can be used to fight the disease. Gene therapy is also being used to correct deficiencies in the production of dopamine, such as in Parkinsons disease, correct some immune system problems, and restore components needed for normal blood cell function in those with certain blood diseases, such hemophilia and beta-Thalassemia. Gene therapy holds promise for treating a wide range of diseases, including cancer, cystic fibrosis, heart disease, diabetes, hemophilia and AIDS.

Potential Risks

Gene therapy does come with some potential risks, all of which, researchers are hoping to overcome. Because the genes have to be delivered using a carrier or vector, the bodys immune system may see the newly introduced viruses as intruders and attack them. Its also possible that the altered viruses may infect additional cells, not just the targeted cells containing mutated genes. There may also be some concern that the viruses may recover their original ability to cause disease, or that the new genes get inserted in the wrong spot in a patients DNA, leading to tumor formation.

Hope for the Future

Gene therapy holds promise as an effective treatment option for a variety of diseases at some point in the near future. An estimated 4,000 medical conditions are a result of gene disorders. If some of these genetic problems can be corrected through gene replacement or manipulation, individuals suffering from these diseases may enjoy longer, healthier lives, free of symptoms and the associated medical expenses.

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Gene Therapy The Future of Medicine? | Science Care

Gene therapy | medicine | Britannica.com

Gene therapy, also called gene transfer therapy, introduction of a normal gene into an individuals genome in order to repair a mutation that causes a genetic disease. When a normal gene is inserted into the nucleus of a mutant cell, the gene most likely will integrate into a chromosomal site different from the defective allele; although that may repair the mutation, a new mutation may result if the normal gene integrates into another functional gene. If the normal gene replaces the mutant allele, there is a chance that the transformed cells will proliferate and produce enough normal gene product for the entire body to be restored to the undiseased phenotype.

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cancer: Gene therapy

Knowledge about the genetic defects that lead to cancer suggests that cancer can be treated by fixing those altered genes. One strategy is to replace a defective gene with its normal counterpart, using methods of recombinant DNA technology. Methods to insert genes into

Human gene therapy has been attempted on somatic (body) cells for diseases such as cystic fibrosis, adenosine deaminase deficiency, familial hypercholesterolemia, cancer, and severe combined immunodeficiency (SCID) syndrome. Somatic cells cured by gene therapy may reverse the symptoms of disease in the treated individual, but the modification is not passed on to the next generation. Germline gene therapy aims to place corrected cells inside the germ line (e.g., cells of the ovary or testis). If that is achieved, those cells will undergo meiosis and provide a normal gametic contribution to the next generation. Germline gene therapy has been achieved experimentally in animals but not in humans.

Scientists have also explored the possibility of combining gene therapy with stem cell therapy. In a preliminary test of that approach, scientists collected skin cells from a patient with alpha-1 antitrypsin deficiency (an inherited disorder associated with certain types of lung and liver disease), reprogrammed the cells into stem cells, corrected the causative gene mutation, and then stimulated the cells to mature into liver cells. The reprogrammed, genetically corrected cells functioned normally.

Prerequisites for gene therapy include finding the best delivery system (often a virus, typically referred to as a viral vector) for the gene, demonstrating that the transferred gene can express itself in the host cell, and establishing that the procedure is safe. Few clinical trials of gene therapy in humans have satisfied all those conditions, often because the delivery system fails to reach cells or the genes are not expressed by cells. Improved gene therapy systems are being developed by using nanotechnology. A promising application of that research involves packaging genes into nanoparticles that are targeted to cancer cells, thereby killing cancer cells specifically and leaving healthy cells unharmed.

Some aspects of gene therapy, including genetic manipulation and selection, research on embryonic tissue, and experimentation on human subjects, have aroused ethical controversy and safety concerns. Some objections to gene therapy are based on the view that humans should not play God and interfere in the natural order. On the other hand, others have argued that genetic engineering may be justified where it is consistent with the purposes of God as creator. Some critics are particularly concerned about the safety of germline gene therapy, because any harm caused by such treatment could be passed to successive generations. Benefits, however, would also be passed on indefinitely. There also has been concern that the use of somatic gene therapy may affect germ cells.

Although the successful use of somatic gene therapy has been reported, clinical trials have revealed risks. In 1999 American teenager Jesse Gelsinger died after having taken part in a gene therapy trial. In 2000 researchers in France announced that they had successfully used gene therapy to treat infants who suffered from X-linked SCID (XSCID; an inherited disorder that affects males). The researchers treated 11 patients, two of whom later developed a leukemia-like illness. Those outcomes highlight the difficulties foreseen in the use of viral vectors in somatic gene therapy. Although the viruses that are used as vectors are disabled so that they cannot replicate, patients may suffer an immune response.

Another concern associated with gene therapy is that it represents a form of eugenics, which aims to improve future generations through the selection of desired traits. Some have argued that gene therapy is eugenic but that it is a treatment that can be adopted to avoid disability. To others, such a view of gene therapy legitimates the so-called medical model of disability (in which disability is seen as an individual problem to be fixed with medicine) and raises peoples hopes for new treatments that may never materialize.

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Gene therapy | medicine | Britannica.com

Gene therapy – Wikipedia

In the medicine field, gene therapy (also called human gene transfer) is the therapeutic delivery of nucleic acid into a patient’s cells as a drug to treat disease.[1][2] The first attempt at modifying human DNA was performed in 1980 by Martin Cline, but the first successful nuclear gene transfer in humans, approved by the National Institutes of Health, was performed in May 1989.[3] The first therapeutic use of gene transfer as well as the first direct insertion of human DNA into the nuclear genome was performed by French Anderson in a trial starting in September 1990.

Between 1989 and February 2016, over 2,300 clinical trials had been conducted, more than half of them in phase I.[4]

Not all medical procedures that introduce alterations to a patient’s genetic makeup can be considered gene therapy. Bone marrow transplantation and organ transplants in general have been found to introduce foreign DNA into patients.[5] Gene therapy is defined by the precision of the procedure and the intention of direct therapeutic effect.

Gene therapy was conceptualized in 1972, by authors who urged caution before commencing human gene therapy studies.

The first attempt, an unsuccessful one, at gene therapy (as well as the first case of medical transfer of foreign genes into humans not counting organ transplantation) was performed by Martin Cline on 10 July 1980.[6][7] Cline claimed that one of the genes in his patients was active six months later, though he never published this data or had it verified[8] and even if he is correct, it’s unlikely it produced any significant beneficial effects treating beta-thalassemia.

After extensive research on animals throughout the 1980s and a 1989 bacterial gene tagging trial on humans, the first gene therapy widely accepted as a success was demonstrated in a trial that started on 14 September 1990, when Ashi DeSilva was treated for ADA-SCID.[9]

The first somatic treatment that produced a permanent genetic change was performed in 1993.[citation needed]

Gene therapy is a way to fix a genetic problem at its source. The polymers are either translated into proteins, interfere with target gene expression, or possibly correct genetic mutations.

The most common form uses DNA that encodes a functional, therapeutic gene to replace a mutated gene. The polymer molecule is packaged within a “vector”, which carries the molecule inside cells.

Early clinical failures led to dismissals of gene therapy. Clinical successes since 2006 regained researchers’ attention, although as of 2014, it was still largely an experimental technique.[10] These include treatment of retinal diseases Leber’s congenital amaurosis[11][12][13][14] and choroideremia,[15] X-linked SCID,[16] ADA-SCID,[17][18] adrenoleukodystrophy,[19] chronic lymphocytic leukemia (CLL),[20] acute lymphocytic leukemia (ALL),[21] multiple myeloma,[22] haemophilia,[18] and Parkinson’s disease.[23] Between 2013 and April 2014, US companies invested over $600 million in the field.[24]

The first commercial gene therapy, Gendicine, was approved in China in 2003 for the treatment of certain cancers.[25] In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia.[26]In 2012 Glybera, a treatment for a rare inherited disorder, became the first treatment to be approved for clinical use in either Europe or the United States after its endorsement by the European Commission.[10][27]

Following early advances in genetic engineering of bacteria, cells, and small animals, scientists started considering how to apply it to medicine. Two main approaches were considered replacing or disrupting defective genes.[28] Scientists focused on diseases caused by single-gene defects, such as cystic fibrosis, haemophilia, muscular dystrophy, thalassemia, and sickle cell anemia. Glybera treats one such disease, caused by a defect in lipoprotein lipase.[27]

DNA must be administered, reach the damaged cells, enter the cell and either express or disrupt a protein.[29] Multiple delivery techniques have been explored. The initial approach incorporated DNA into an engineered virus to deliver the DNA into a chromosome.[30][31] Naked DNA approaches have also been explored, especially in the context of vaccine development.[32]

Generally, efforts focused on administering a gene that causes a needed protein to be expressed. More recently, increased understanding of nuclease function has led to more direct DNA editing, using techniques such as zinc finger nucleases and CRISPR. The vector incorporates genes into chromosomes. The expressed nucleases then knock out and replace genes in the chromosome. As of 2014 these approaches involve removing cells from patients, editing a chromosome and returning the transformed cells to patients.[33]

Gene editing is a potential approach to alter the human genome to treat genetic diseases,[34] viral diseases,[35] and cancer.[36] As of 2016 these approaches were still years from being medicine.[37][38]

Gene therapy may be classified into two types:

In somatic cell gene therapy (SCGT), the therapeutic genes are transferred into any cell other than a gamete, germ cell, gametocyte, or undifferentiated stem cell. Any such modifications affect the individual patient only, and are not inherited by offspring. Somatic gene therapy represents mainstream basic and clinical research, in which therapeutic DNA (either integrated in the genome or as an external episome or plasmid) is used to treat disease.

Over 600 clinical trials utilizing SCGT are underway[when?] in the US. Most focus on severe genetic disorders, including immunodeficiencies, haemophilia, thalassaemia, and cystic fibrosis. Such single gene disorders are good candidates for somatic cell therapy. The complete correction of a genetic disorder or the replacement of multiple genes is not yet possible. Only a few of the trials are in the advanced stages.[39]

In germline gene therapy (GGT), germ cells (sperm or egg cells) are modified by the introduction of functional genes into their genomes. Modifying a germ cell causes all the organism’s cells to contain the modified gene. The change is therefore heritable and passed on to later generations. Australia, Canada, Germany, Israel, Switzerland, and the Netherlands[40] prohibit GGT for application in human beings, for technical and ethical reasons, including insufficient knowledge about possible risks to future generations[40] and higher risks versus SCGT.[41] The US has no federal controls specifically addressing human genetic modification (beyond FDA regulations for therapies in general).[40][42][43][44]

The delivery of DNA into cells can be accomplished by multiple methods. The two major classes are recombinant viruses (sometimes called biological nanoparticles or viral vectors) and naked DNA or DNA complexes (non-viral methods).

In order to replicate, viruses introduce their genetic material into the host cell, tricking the host’s cellular machinery into using it as blueprints for viral proteins. Retroviruses go a stage further by having their genetic material copied into the genome of the host cell. Scientists exploit this by substituting a virus’s genetic material with therapeutic DNA. (The term ‘DNA’ may be an oversimplification, as some viruses contain RNA, and gene therapy could take this form as well.) A number of viruses have been used for human gene therapy, including retroviruses, adenoviruses, herpes simplex, vaccinia, and adeno-associated virus.[4] Like the genetic material (DNA or RNA) in viruses, therapeutic DNA can be designed to simply serve as a temporary blueprint that is degraded naturally or (at least theoretically) to enter the host’s genome, becoming a permanent part of the host’s DNA in infected cells.

Non-viral methods present certain advantages over viral methods, such as large scale production and low host immunogenicity. However, non-viral methods initially produced lower levels of transfection and gene expression, and thus lower therapeutic efficacy. Later technology remedied this deficiency.[citation needed]

Methods for non-viral gene therapy include the injection of naked DNA, electroporation, the gene gun, sonoporation, magnetofection, the use of oligonucleotides, lipoplexes, dendrimers, and inorganic nanoparticles.

Some of the unsolved problems include:

Three patients’ deaths have been reported in gene therapy trials, putting the field under close scrutiny. The first was that of Jesse Gelsinger, who died in 1999 because of immune rejection response.[51] One X-SCID patient died of leukemia in 2003.[9] In 2007, a rheumatoid arthritis patient died from an infection; the subsequent investigation concluded that the death was not related to gene therapy.[52]

In 1972 Friedmann and Roblin authored a paper in Science titled “Gene therapy for human genetic disease?”[53] Rogers (1970) was cited for proposing that exogenous good DNA be used to replace the defective DNA in those who suffer from genetic defects.[54]

In 1984 a retrovirus vector system was designed that could efficiently insert foreign genes into mammalian chromosomes.[55]

The first approved gene therapy clinical research in the US took place on 14 September 1990, at the National Institutes of Health (NIH), under the direction of William French Anderson.[56] Four-year-old Ashanti DeSilva received treatment for a genetic defect that left her with ADA-SCID, a severe immune system deficiency. The defective gene of the patient’s blood cells was replaced by the functional variant. Ashantis immune system was partially restored by the therapy. Production of the missing enzyme was temporarily stimulated, but the new cells with functional genes were not generated. She led a normal life only with the regular injections performed every two months. The effects were successful, but temporary.[57]

Cancer gene therapy was introduced in 1992/93 (Trojan et al. 1993).[58] The treatment of glioblastoma multiforme, the malignant brain tumor whose outcome is always fatal, was done using a vector expressing antisense IGF-I RNA (clinical trial approved by NIH protocolno.1602 November 24, 1993,[59] and by the FDA in 1994). This therapy also represents the beginning of cancer immunogene therapy, a treatment which proves to be effective due to the anti-tumor mechanism of IGF-I antisense, which is related to strong immune and apoptotic phenomena.

In 1992 Claudio Bordignon, working at the Vita-Salute San Raffaele University, performed the first gene therapy procedure using hematopoietic stem cells as vectors to deliver genes intended to correct hereditary diseases.[60] In 2002 this work led to the publication of the first successful gene therapy treatment for adenosine deaminase deficiency (ADA-SCID). The success of a multi-center trial for treating children with SCID (severe combined immune deficiency or “bubble boy” disease) from 2000 and 2002, was questioned when two of the ten children treated at the trial’s Paris center developed a leukemia-like condition. Clinical trials were halted temporarily in 2002, but resumed after regulatory review of the protocol in the US, the United Kingdom, France, Italy, and Germany.[61]

In 1993 Andrew Gobea was born with SCID following prenatal genetic screening. Blood was removed from his mother’s placenta and umbilical cord immediately after birth, to acquire stem cells. The allele that codes for adenosine deaminase (ADA) was obtained and inserted into a retrovirus. Retroviruses and stem cells were mixed, after which the viruses inserted the gene into the stem cell chromosomes. Stem cells containing the working ADA gene were injected into Andrew’s blood. Injections of the ADA enzyme were also given weekly. For four years T cells (white blood cells), produced by stem cells, made ADA enzymes using the ADA gene. After four years more treatment was needed.[62]

Jesse Gelsinger’s death in 1999 impeded gene therapy research in the US.[63][64] As a result, the FDA suspended several clinical trials pending the reevaluation of ethical and procedural practices.[65]

The modified cancer gene therapy strategy of antisense IGF-I RNA (NIH n 1602)[59] using antisense / triple helix anti-IGF-I approach was registered in 2002 by Wiley gene therapy clinical trial – n 635 and 636. The approach has shown promising results in the treatment of six different malignant tumors: glioblastoma, cancers of liver, colon, prostate, uterus, and ovary (Collaborative NATO Science Programme on Gene Therapy USA, France, Poland n LST 980517 conducted by J. Trojan) (Trojan et al., 2012). This anti-gene antisense/triple helix therapy has proven to be efficient, due to the mechanism stopping simultaneously IGF-I expression on translation and transcription levels, strengthening anti-tumor immune and apoptotic phenomena.

Sickle-cell disease can be treated in mice.[66] The mice which have essentially the same defect that causes human cases used a viral vector to induce production of fetal hemoglobin (HbF), which normally ceases to be produced shortly after birth. In humans, the use of hydroxyurea to stimulate the production of HbF temporarily alleviates sickle cell symptoms. The researchers demonstrated this treatment to be a more permanent means to increase therapeutic HbF production.[67]

A new gene therapy approach repaired errors in messenger RNA derived from defective genes. This technique has the potential to treat thalassaemia, cystic fibrosis and some cancers.[68]

Researchers created liposomes 25 nanometers across that can carry therapeutic DNA through pores in the nuclear membrane.[69]

In 2003 a research team inserted genes into the brain for the first time. They used liposomes coated in a polymer called polyethylene glycol, which unlike viral vectors, are small enough to cross the bloodbrain barrier.[70]

Short pieces of double-stranded RNA (short, interfering RNAs or siRNAs) are used by cells to degrade RNA of a particular sequence. If a siRNA is designed to match the RNA copied from a faulty gene, then the abnormal protein product of that gene will not be produced.[71]

Gendicine is a cancer gene therapy that delivers the tumor suppressor gene p53 using an engineered adenovirus. In 2003, it was approved in China for the treatment of head and neck squamous cell carcinoma.[25]

In March researchers announced the successful use of gene therapy to treat two adult patients for X-linked chronic granulomatous disease, a disease which affects myeloid cells and damages the immune system. The study is the first to show that gene therapy can treat the myeloid system.[72]

In May a team reported a way to prevent the immune system from rejecting a newly delivered gene.[73] Similar to organ transplantation, gene therapy has been plagued by this problem. The immune system normally recognizes the new gene as foreign and rejects the cells carrying it. The research utilized a newly uncovered network of genes regulated by molecules known as microRNAs. This natural function selectively obscured their therapeutic gene in immune system cells and protected it from discovery. Mice infected with the gene containing an immune-cell microRNA target sequence did not reject the gene.

In August scientists successfully treated metastatic melanoma in two patients using killer T cells genetically retargeted to attack the cancer cells.[74]

In November researchers reported on the use of VRX496, a gene-based immunotherapy for the treatment of HIV that uses a lentiviral vector to deliver an antisense gene against the HIV envelope. In a phase I clinical trial, five subjects with chronic HIV infection who had failed to respond to at least two antiretroviral regimens were treated. A single intravenous infusion of autologous CD4 T cells genetically modified with VRX496 was well tolerated. All patients had stable or decreased viral load; four of the five patients had stable or increased CD4 T cell counts. All five patients had stable or increased immune response to HIV antigens and other pathogens. This was the first evaluation of a lentiviral vector administered in a US human clinical trial.[75][76]

In May researchers announced the first gene therapy trial for inherited retinal disease. The first operation was carried out on a 23-year-old British male, Robert Johnson, in early 2007.[77]

Leber’s congenital amaurosis is an inherited blinding disease caused by mutations in the RPE65 gene. The results of a small clinical trial in children were published in April.[11] Delivery of recombinant adeno-associated virus (AAV) carrying RPE65 yielded positive results. In May two more groups reported positive results in independent clinical trials using gene therapy to treat the condition. In all three clinical trials, patients recovered functional vision without apparent side-effects.[11][12][13][14]

In September researchers were able to give trichromatic vision to squirrel monkeys.[78] In November 2009, researchers halted a fatal genetic disorder called adrenoleukodystrophy in two children using a lentivirus vector to deliver a functioning version of ABCD1, the gene that is mutated in the disorder.[79]

An April paper reported that gene therapy addressed achromatopsia (color blindness) in dogs by targeting cone photoreceptors. Cone function and day vision were restored for at least 33 months in two young specimens. The therapy was less efficient for older dogs.[80]

In September it was announced that an 18-year-old male patient in France with beta-thalassemia major had been successfully treated.[81] Beta-thalassemia major is an inherited blood disease in which beta haemoglobin is missing and patients are dependent on regular lifelong blood transfusions.[82] The technique used a lentiviral vector to transduce the human -globin gene into purified blood and marrow cells obtained from the patient in June 2007.[83] The patient’s haemoglobin levels were stable at 9 to 10 g/dL. About a third of the hemoglobin contained the form introduced by the viral vector and blood transfusions were not needed.[83][84] Further clinical trials were planned.[85] Bone marrow transplants are the only cure for thalassemia, but 75% of patients do not find a matching donor.[84]

Cancer immunogene therapy using modified antigene, antisense/triple helix approach was introduced in South America in 2010/11 in La Sabana University, Bogota (Ethical Committee 14 December 2010, no P-004-10). Considering the ethical aspect of gene diagnostic and gene therapy targeting IGF-I, the IGF-I expressing tumors i.e. lung and epidermis cancers were treated (Trojan et al. 2016).[86][87]

In 2007 and 2008, a man (Timothy Ray Brown) was cured of HIV by repeated hematopoietic stem cell transplantation (see also allogeneic stem cell transplantation, allogeneic bone marrow transplantation, allotransplantation) with double-delta-32 mutation which disables the CCR5 receptor. This cure was accepted by the medical community in 2011.[88] It required complete ablation of existing bone marrow, which is very debilitating.

In August two of three subjects of a pilot study were confirmed to have been cured from chronic lymphocytic leukemia (CLL). The therapy used genetically modified T cells to attack cells that expressed the CD19 protein to fight the disease.[20] In 2013, the researchers announced that 26 of 59 patients had achieved complete remission and the original patient had remained tumor-free.[89]

Human HGF plasmid DNA therapy of cardiomyocytes is being examined as a potential treatment for coronary artery disease as well as treatment for the damage that occurs to the heart after myocardial infarction.[90][91]

In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia; it delivers the gene encoding for VEGF.[92][26] Neovasculogen is a plasmid encoding the CMV promoter and the 165 amino acid form of VEGF.[93][94]

The FDA approved Phase 1 clinical trials on thalassemia major patients in the US for 10 participants in July.[95] The study was expected to continue until 2015.[85]

In July 2012, the European Medicines Agency recommended approval of a gene therapy treatment for the first time in either Europe or the United States. The treatment used Alipogene tiparvovec (Glybera) to compensate for lipoprotein lipase deficiency, which can cause severe pancreatitis.[96] The recommendation was endorsed by the European Commission in November 2012[10][27][97][98] and commercial rollout began in late 2014.[99] Alipogene tiparvovec was expected to cost around $1.6 million per treatment in 2012,[100] revised to $1 million in 2015,[101] making it the most expensive medicine in the world at the time.[102] As of 2016, only one person had been treated with drug.[103]

In December 2012, it was reported that 10 of 13 patients with multiple myeloma were in remission “or very close to it” three months after being injected with a treatment involving genetically engineered T cells to target proteins NY-ESO-1 and LAGE-1, which exist only on cancerous myeloma cells.[22]

In March researchers reported that three of five adult subjects who had acute lymphocytic leukemia (ALL) had been in remission for five months to two years after being treated with genetically modified T cells which attacked cells with CD19 genes on their surface, i.e. all B-cells, cancerous or not. The researchers believed that the patients’ immune systems would make normal T-cells and B-cells after a couple of months. They were also given bone marrow. One patient relapsed and died and one died of a blood clot unrelated to the disease.[21]

Following encouraging Phase 1 trials, in April, researchers announced they were starting Phase 2 clinical trials (called CUPID2 and SERCA-LVAD) on 250 patients[104] at several hospitals to combat heart disease. The therapy was designed to increase the levels of SERCA2, a protein in heart muscles, improving muscle function.[105] The FDA granted this a Breakthrough Therapy Designation to accelerate the trial and approval process.[106] In 2016 it was reported that no improvement was found from the CUPID 2 trial.[107]

In July researchers reported promising results for six children with two severe hereditary diseases had been treated with a partially deactivated lentivirus to replace a faulty gene and after 732 months. Three of the children had metachromatic leukodystrophy, which causes children to lose cognitive and motor skills.[108] The other children had Wiskott-Aldrich syndrome, which leaves them to open to infection, autoimmune diseases, and cancer.[109] Follow up trials with gene therapy on another six children with Wiskott-Aldrich syndrome were also reported as promising.[110][111]

In October researchers reported that two children born with adenosine deaminase severe combined immunodeficiency disease (ADA-SCID) had been treated with genetically engineered stem cells 18 months previously and that their immune systems were showing signs of full recovery. Another three children were making progress.[18] In 2014 a further 18 children with ADA-SCID were cured by gene therapy.[112] ADA-SCID children have no functioning immune system and are sometimes known as “bubble children.”[18]

Also in October researchers reported that they had treated six hemophilia sufferers in early 2011 using an adeno-associated virus. Over two years later all six were producing clotting factor.[18][113]

In January researchers reported that six choroideremia patients had been treated with adeno-associated virus with a copy of REP1. Over a six-month to two-year period all had improved their sight.[114][115] By 2016, 32 patients had been treated with positive results and researchers were hopeful the treatment would be long-lasting.[15] Choroideremia is an inherited genetic eye disease with no approved treatment, leading to loss of sight.

In March researchers reported that 12 HIV patients had been treated since 2009 in a trial with a genetically engineered virus with a rare mutation (CCR5 deficiency) known to protect against HIV with promising results.[116][117]

Clinical trials of gene therapy for sickle cell disease were started in 2014.[118][119] There is a need for high quality randomised controlled trials assessing the risks and benefits involved with gene therapy for people with sickle cell disease.[120]

In February LentiGlobin BB305, a gene therapy treatment undergoing clinical trials for treatment of beta thalassemia gained FDA “breakthrough” status after several patients were able to forgo the frequent blood transfusions usually required to treat the disease.[121]

In March researchers delivered a recombinant gene encoding a broadly neutralizing antibody into monkeys infected with simian HIV; the monkeys’ cells produced the antibody, which cleared them of HIV. The technique is named immunoprophylaxis by gene transfer (IGT). Animal tests for antibodies to ebola, malaria, influenza, and hepatitis were underway.[122][123]

In March, scientists, including an inventor of CRISPR, Jennifer Doudna, urged a worldwide moratorium on germline gene therapy, writing “scientists should avoid even attempting, in lax jurisdictions, germline genome modification for clinical application in humans” until the full implications “are discussed among scientific and governmental organizations”.[124][125][126][127]

In October, researchers announced that they had treated a baby girl, Layla Richards, with an experimental treatment using donor T-cells genetically engineered using TALEN to attack cancer cells. One year after the treatment she was still free of her cancer (a highly aggressive form of acute lymphoblastic leukaemia [ALL]).[128] Children with highly aggressive ALL normally have a very poor prognosis and Layla’s disease had been regarded as terminal before the treatment.[129]

In December, scientists of major world academies called for a moratorium on inheritable human genome edits, including those related to CRISPR-Cas9 technologies[130] but that basic research including embryo gene editing should continue.[131]

In April the Committee for Medicinal Products for Human Use of the European Medicines Agency endorsed a gene therapy treatment called Strimvelis[132][133] and the European Commission approved it in June.[134] This treats children born with adenosine deaminase deficiency and who have no functioning immune system. This was the second gene therapy treatment to be approved in Europe.[135]

In October, Chinese scientists reported they had started a trial to genetically modify T-cells from 10 adult patients with lung cancer and reinject the modified T-cells back into their bodies to attack the cancer cells. The T-cells had the PD-1 protein (which stops or slows the immune response) removed using CRISPR-Cas9.[136][137]

A 2016 Cochrane systematic review looking at data from four trials on topical cystic fibrosis transmembrane conductance regulator (CFTR) gene therapy does not support its clinical use as a mist inhaled into the lungs to treat cystic fibrosis patients with lung infections. One of the four trials did find weak evidence that liposome-based CFTR gene transfer therapy may lead to a small respiratory improvement for people with CF. This weak evidence is not enough to make a clinical recommendation for routine CFTR gene therapy.[138]

In February Kite Pharma announced results from a clinical trial of CAR-T cells in around a hundred people with advanced Non-Hodgkin lymphoma.[139]

In March, French scientists reported on clinical research of gene therapy to treat sickle-cell disease.[140]

In August, the FDA approved tisagenlecleucel for acute lymphoblastic leukemia.[141] Tisagenlecleucel is an adoptive cell transfer therapy for B-cell acute lymphoblastic leukemia; T cells from a person with cancer are removed, genetically engineered to make a specific T-cell receptor (a chimeric T cell receptor, or “CAR-T”) that reacts to the cancer, and are administered back to the person. The T cells are engineered to target a protein called CD19 that is common on B cells. This is the first form of gene therapy to be approved in the United States. In October, a similar therapy called axicabtagene ciloleucel was approved for non-Hodgkin lymphoma.[142]

In December the results of using an adeno-associated virus with blood clotting factor VIII to treat nine haemophilia A patients were published. Six of the seven patients on the high dose regime increased the level of the blood clotting VIII to normal levels. The low and medium dose regimes had no effect on the patient’s blood clotting levels.[143][144]

In December, the FDA approved Luxturna, the first in vivo gene therapy, for the treatment of blindness due to Leber’s congenital amaurosis.[145] The price of this treatment was 850,000 US dollars for both eyes.[146][147]

Speculated uses for gene therapy include:

Gene therapy techniques have the potential to provide alternative treatments for those with infertility. Recently, successful experimentation on mice has proven that fertility can be restored by using the gene therapy method, CRISPR.[148] Spermatogenical stem cells from another organism were transplanted into the testes of an infertile male mouse. The stem cells re-established spermatogenesis and fertility.[149]

Athletes might adopt gene therapy technologies to improve their performance.[150] Gene doping is not known to occur, but multiple gene therapies may have such effects. Kayser et al. argue that gene doping could level the playing field if all athletes receive equal access. Critics claim that any therapeutic intervention for non-therapeutic/enhancement purposes compromises the ethical foundations of medicine and sports.[151]

Genetic engineering could be used to cure diseases, but also to change physical appearance, metabolism, and even improve physical capabilities and mental faculties such as memory and intelligence. Ethical claims about germline engineering include beliefs that every fetus has a right to remain genetically unmodified, that parents hold the right to genetically modify their offspring, and that every child has the right to be born free of preventable diseases.[152][153][154] For parents, genetic engineering could be seen as another child enhancement technique to add to diet, exercise, education, training, cosmetics, and plastic surgery.[155][156] Another theorist claims that moral concerns limit but do not prohibit germline engineering.[157]

Possible regulatory schemes include a complete ban, provision to everyone, or professional self-regulation. The American Medical Associations Council on Ethical and Judicial Affairs stated that “genetic interventions to enhance traits should be considered permissible only in severely restricted situations: (1) clear and meaningful benefits to the fetus or child; (2) no trade-off with other characteristics or traits; and (3) equal access to the genetic technology, irrespective of income or other socioeconomic characteristics.”[158]

As early in the history of biotechnology as 1990, there have been scientists opposed to attempts to modify the human germline using these new tools,[159] and such concerns have continued as technology progressed.[160][161] With the advent of new techniques like CRISPR, in March 2015 a group of scientists urged a worldwide moratorium on clinical use of gene editing technologies to edit the human genome in a way that can be inherited.[124][125][126][127] In April 2015, researchers sparked controversy when they reported results of basic research to edit the DNA of non-viable human embryos using CRISPR.[148][162] A committee of the American National Academy of Sciences and National Academy of Medicine gave qualified support to human genome editing in 2017[163][164] once answers have been found to safety and efficiency problems “but only for serious conditions under stringent oversight.”[165]

Regulations covering genetic modification are part of general guidelines about human-involved biomedical research. There are no international treaties which are legally binding in this area, but there are recommendations for national laws from various bodies.

The Helsinki Declaration (Ethical Principles for Medical Research Involving Human Subjects) was amended by the World Medical Association’s General Assembly in 2008. This document provides principles physicians and researchers must consider when involving humans as research subjects. The Statement on Gene Therapy Research initiated by the Human Genome Organization (HUGO) in 2001 provides a legal baseline for all countries. HUGOs document emphasizes human freedom and adherence to human rights, and offers recommendations for somatic gene therapy, including the importance of recognizing public concerns about such research.[166]

No federal legislation lays out protocols or restrictions about human genetic engineering. This subject is governed by overlapping regulations from local and federal agencies, including the Department of Health and Human Services, the FDA and NIH’s Recombinant DNA Advisory Committee. Researchers seeking federal funds for an investigational new drug application, (commonly the case for somatic human genetic engineering,) must obey international and federal guidelines for the protection of human subjects.[167]

NIH serves as the main gene therapy regulator for federally funded research. Privately funded research is advised to follow these regulations. NIH provides funding for research that develops or enhances genetic engineering techniques and to evaluate the ethics and quality in current research. The NIH maintains a mandatory registry of human genetic engineering research protocols that includes all federally funded projects.

An NIH advisory committee published a set of guidelines on gene manipulation.[168] The guidelines discuss lab safety as well as human test subjects and various experimental types that involve genetic changes. Several sections specifically pertain to human genetic engineering, including Section III-C-1. This section describes required review processes and other aspects when seeking approval to begin clinical research involving genetic transfer into a human patient.[169] The protocol for a gene therapy clinical trial must be approved by the NIH’s Recombinant DNA Advisory Committee prior to any clinical trial beginning; this is different from any other kind of clinical trial.[168]

As with other kinds of drugs, the FDA regulates the quality and safety of gene therapy products and supervises how these products are used clinically. Therapeutic alteration of the human genome falls under the same regulatory requirements as any other medical treatment. Research involving human subjects, such as clinical trials, must be reviewed and approved by the FDA and an Institutional Review Board.[170][171]

Gene therapy is the basis for the plotline of the film I Am Legend[172] and the TV show Will Gene Therapy Change the Human Race?.[173] In 1994, gene therapy was a plot element in The Erlenmeyer Flask, The X-Files’ first season finale. It is also used in Stargate as a means of allowing humans to use Ancient technology.[174]

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Gene therapy – Wikipedia

Gene therapy | medicine | Britannica.com

Gene therapy, also called gene transfer therapy, introduction of a normal gene into an individuals genome in order to repair a mutation that causes a genetic disease. When a normal gene is inserted into the nucleus of a mutant cell, the gene most likely will integrate into a chromosomal site different from the defective allele; although that may repair the mutation, a new mutation may result if the normal gene integrates into another functional gene. If the normal gene replaces the mutant allele, there is a chance that the transformed cells will proliferate and produce enough normal gene product for the entire body to be restored to the undiseased phenotype.

Read More on This Topic

cancer: Gene therapy

Knowledge about the genetic defects that lead to cancer suggests that cancer can be treated by fixing those altered genes. One strategy is to replace a defective gene with its normal counterpart, using methods of recombinant DNA technology. Methods to insert genes into

Human gene therapy has been attempted on somatic (body) cells for diseases such as cystic fibrosis, adenosine deaminase deficiency, familial hypercholesterolemia, cancer, and severe combined immunodeficiency (SCID) syndrome. Somatic cells cured by gene therapy may reverse the symptoms of disease in the treated individual, but the modification is not passed on to the next generation. Germline gene therapy aims to place corrected cells inside the germ line (e.g., cells of the ovary or testis). If that is achieved, those cells will undergo meiosis and provide a normal gametic contribution to the next generation. Germline gene therapy has been achieved experimentally in animals but not in humans.

Scientists have also explored the possibility of combining gene therapy with stem cell therapy. In a preliminary test of that approach, scientists collected skin cells from a patient with alpha-1 antitrypsin deficiency (an inherited disorder associated with certain types of lung and liver disease), reprogrammed the cells into stem cells, corrected the causative gene mutation, and then stimulated the cells to mature into liver cells. The reprogrammed, genetically corrected cells functioned normally.

Prerequisites for gene therapy include finding the best delivery system (often a virus, typically referred to as a viral vector) for the gene, demonstrating that the transferred gene can express itself in the host cell, and establishing that the procedure is safe. Few clinical trials of gene therapy in humans have satisfied all those conditions, often because the delivery system fails to reach cells or the genes are not expressed by cells. Improved gene therapy systems are being developed by using nanotechnology. A promising application of that research involves packaging genes into nanoparticles that are targeted to cancer cells, thereby killing cancer cells specifically and leaving healthy cells unharmed.

Some aspects of gene therapy, including genetic manipulation and selection, research on embryonic tissue, and experimentation on human subjects, have aroused ethical controversy and safety concerns. Some objections to gene therapy are based on the view that humans should not play God and interfere in the natural order. On the other hand, others have argued that genetic engineering may be justified where it is consistent with the purposes of God as creator. Some critics are particularly concerned about the safety of germline gene therapy, because any harm caused by such treatment could be passed to successive generations. Benefits, however, would also be passed on indefinitely. There also has been concern that the use of somatic gene therapy may affect germ cells.

Although the successful use of somatic gene therapy has been reported, clinical trials have revealed risks. In 1999 American teenager Jesse Gelsinger died after having taken part in a gene therapy trial. In 2000 researchers in France announced that they had successfully used gene therapy to treat infants who suffered from X-linked SCID (XSCID; an inherited disorder that affects males). The researchers treated 11 patients, two of whom later developed a leukemia-like illness. Those outcomes highlight the difficulties foreseen in the use of viral vectors in somatic gene therapy. Although the viruses that are used as vectors are disabled so that they cannot replicate, patients may suffer an immune response.

Another concern associated with gene therapy is that it represents a form of eugenics, which aims to improve future generations through the selection of desired traits. Some have argued that gene therapy is eugenic but that it is a treatment that can be adopted to avoid disability. To others, such a view of gene therapy legitimates the so-called medical model of disability (in which disability is seen as an individual problem to be fixed with medicine) and raises peoples hopes for new treatments that may never materialize.

Original post:

Gene therapy | medicine | Britannica.com

Gene Therapy – Genetics Generation

What is Gene Therapy?

Gene therapy is a technique used to correct defective genes genes that are responsible for disease development. Specifically, according to the American Society of Gene and Cell Therapy-

Gene therapy is defined as a set of strategies that modify the expressionof an individuals genes or that correct abnormal genes. Each strategyinvolves the administration of a specific DNA (or RNA).

Gene therapy is the manipulation of the expression of specific genes in a persons body, in hopes of treating a disease or disorder. Gene therapy is still considered experimental and only available via clinical trial. Although many successful trials have been documented (see Interesting Links below), gene therapy has a checkered history. In some gene therapy trials, there were cases of leukemia as an unintended side-effect, and even cases of death (see link on Jesse Gelsinger below).

Image courtesy of Wikimedia Commons

How Does Gene Therapy Work?

Although there are several strategies for gene therapy, the most commonly used method involves inserting a therapeutic gene into the genome to replace the abnormal or disease-causing gene. The gene that is inserted is delivered into a target cell via a vector. Usually, this vector is a virus, although non-viral vectors are in development. Viruses are a good choice for introducing genes into a cell because they typically operate by transferring their own genetic material while replicating themselves. Once target cells are infected with the viral vector, the vector releases its therapeutic gene which then incorporates into the cells DNA. The goal is that the cell will start using the new gene to make functional, healthy proteins.

There are three main strategies for using gene therapy to restore the target cells or target tissues to a normal, healthy state.

1. Insert the functional version of a gene in hopes of replacing the abnormal form. This is used to treat single-gene disorders like hemophilia A and B and cystic fibrosis.

2. Insert a gene that encodes for a therapeutic protein that treats a disease. This is used to treat acquired diseases likeinfection or ischemic heart disease.

3. Use gene transfer to down-regulate gene expression in hopes of decreasing the activity of a harmful gene.

Current Areas of Research

Although gene therapy is still experimental, many diseases have been targets for gene therapy in clinical trials. Some of these trials have produced promising results. Diseases that may be treated successfully in the future with gene therapy include (but are not limited to):* Anemias* Cardiovascular diseases* Cystic Fibrosis* Diabetes* Diseases of the bones and joints* Eye disease and Blindness* Gauschers Disease* Hemophilia* Huntingtons Disease* Lysosomal storage diseases* Muscular Dystrophy* Sickle cell disorder

The main challenges facing gene therapy are the identification of disease causing genes, the targeted delivery of the therapeutic gene specifically to the affected tissues, and the prevention of side effects (such as an immune response) in the patient.

Gene Therapy for Enhancement Purposes

If gene therapy becomes routine medical practice, then it is reasonable to believe that some will seek it out for enhancement purposes. For example, a gene therapy designed to help patients with Alzheimers disease may be appealing to a normal individual hoping to boost memory. One potential area of enhancement that has been discussed is gene doping in sports. Gene doping is defined by the World Anti-Doping Agency (WADA) as the non-therapeutic use of genes, genetic elements and/or cells that have the capacity to enhance athletic performance. The purpose of gene doping is toenhancea given gene rather thancorrecta faulty one. Potential targets of gene doping include:

* Erythropoietin (EPO) for increased production of red blood cells* Insulin-like Growth Factor-1 gene for increased muscle mass* Myostatin for increased muscle mass* Vascular Endothelial Growth Factor (VEGF) for an increase in blood flow

This form of doping would be hard to detect because the doping substances are produced directly in an individuals own cells after these genes with performance-enhancing effects have been expressed. Whether or not to use gene therapy in the future for enhancement purposes, and how to regulate it, will require a complex discussion of ethics in which there will likely be many differing opinions.

Interesting Links*The American Society of Gene and Cell Therapy* National Geographic articleon gene doping* Science Daily article onrecent gene therapy news* New York Times article on the death of Jesse Gelsinger* Scientific American article on treating blindness with gene therapy

CLICK HERE to read our case study involving ethical issues associated with gene therapy

REFERENCES

Gene Therapy and Cell Therapy Defined. American Society of Gene and Cell Therapy, n.d. Web. 04 Nov. 2012. .

Gene Therapy..Human Genome Project Information, n.d. We. 04 Nov. 2012.

Pawliuk R et al. Correction of sickle cell disease in transgenic mouse models by gene therapy. Science. 2001; 294:2368-2371.

Unal M, Unal DO. Gene doping in sports. Sports Medicine. 2004; 34:357-362.

Wells DJ. Gene doping: the hype and the reality. British Journal of Pharmacology. 2008 January; 154: 623-631.

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Gene Therapy – Genetics Generation

Gene therapy | medicine | Britannica.com

Gene therapy, also called gene transfer therapy, introduction of a normal gene into an individuals genome in order to repair a mutation that causes a genetic disease. When a normal gene is inserted into the nucleus of a mutant cell, the gene most likely will integrate into a chromosomal site different from the defective allele; although that may repair the mutation, a new mutation may result if the normal gene integrates into another functional gene. If the normal gene replaces the mutant allele, there is a chance that the transformed cells will proliferate and produce enough normal gene product for the entire body to be restored to the undiseased phenotype.

Read More on This Topic

cancer: Gene therapy

Knowledge about the genetic defects that lead to cancer suggests that cancer can be treated by fixing those altered genes. One strategy is to replace a defective gene with its normal counterpart, using methods of recombinant DNA technology. Methods to insert genes into

Human gene therapy has been attempted on somatic (body) cells for diseases such as cystic fibrosis, adenosine deaminase deficiency, familial hypercholesterolemia, cancer, and severe combined immunodeficiency (SCID) syndrome. Somatic cells cured by gene therapy may reverse the symptoms of disease in the treated individual, but the modification is not passed on to the next generation. Germline gene therapy aims to place corrected cells inside the germ line (e.g., cells of the ovary or testis). If that is achieved, those cells will undergo meiosis and provide a normal gametic contribution to the next generation. Germline gene therapy has been achieved experimentally in animals but not in humans.

Scientists have also explored the possibility of combining gene therapy with stem cell therapy. In a preliminary test of that approach, scientists collected skin cells from a patient with alpha-1 antitrypsin deficiency (an inherited disorder associated with certain types of lung and liver disease), reprogrammed the cells into stem cells, corrected the causative gene mutation, and then stimulated the cells to mature into liver cells. The reprogrammed, genetically corrected cells functioned normally.

Prerequisites for gene therapy include finding the best delivery system (often a virus, typically referred to as a viral vector) for the gene, demonstrating that the transferred gene can express itself in the host cell, and establishing that the procedure is safe. Few clinical trials of gene therapy in humans have satisfied all those conditions, often because the delivery system fails to reach cells or the genes are not expressed by cells. Improved gene therapy systems are being developed by using nanotechnology. A promising application of that research involves packaging genes into nanoparticles that are targeted to cancer cells, thereby killing cancer cells specifically and leaving healthy cells unharmed.

Some aspects of gene therapy, including genetic manipulation and selection, research on embryonic tissue, and experimentation on human subjects, have aroused ethical controversy and safety concerns. Some objections to gene therapy are based on the view that humans should not play God and interfere in the natural order. On the other hand, others have argued that genetic engineering may be justified where it is consistent with the purposes of God as creator. Some critics are particularly concerned about the safety of germline gene therapy, because any harm caused by such treatment could be passed to successive generations. Benefits, however, would also be passed on indefinitely. There also has been concern that the use of somatic gene therapy may affect germ cells.

Although the successful use of somatic gene therapy has been reported, clinical trials have revealed risks. In 1999 American teenager Jesse Gelsinger died after having taken part in a gene therapy trial. In 2000 researchers in France announced that they had successfully used gene therapy to treat infants who suffered from X-linked SCID (XSCID; an inherited disorder that affects males). The researchers treated 11 patients, two of whom later developed a leukemia-like illness. Those outcomes highlight the difficulties foreseen in the use of viral vectors in somatic gene therapy. Although the viruses that are used as vectors are disabled so that they cannot replicate, patients may suffer an immune response.

Another concern associated with gene therapy is that it represents a form of eugenics, which aims to improve future generations through the selection of desired traits. Some have argued that gene therapy is eugenic but that it is a treatment that can be adopted to avoid disability. To others, such a view of gene therapy legitimates the so-called medical model of disability (in which disability is seen as an individual problem to be fixed with medicine) and raises peoples hopes for new treatments that may never materialize.

Continue reading here:

Gene therapy | medicine | Britannica.com

Gene therapy – Wikipedia

In the medicine field, gene therapy (also called human gene transfer) is the therapeutic delivery of nucleic acid into a patient’s cells as a drug to treat disease.[1][2] The first attempt at modifying human DNA was performed in 1980 by Martin Cline, but the first successful nuclear gene transfer in humans, approved by the National Institutes of Health, was performed in May 1989.[3] The first therapeutic use of gene transfer as well as the first direct insertion of human DNA into the nuclear genome was performed by French Anderson in a trial starting in September 1990.

Between 1989 and February 2016, over 2,300 clinical trials had been conducted, more than half of them in phase I.[4]

Not all medical procedures that introduce alterations to a patient’s genetic makeup can be considered gene therapy. Bone marrow transplantation and organ transplants in general have been found to introduce foreign DNA into patients.[5] Gene therapy is defined by the precision of the procedure and the intention of direct therapeutic effect.

Gene therapy was conceptualized in 1972, by authors who urged caution before commencing human gene therapy studies.

The first attempt, an unsuccessful one, at gene therapy (as well as the first case of medical transfer of foreign genes into humans not counting organ transplantation) was performed by Martin Cline on 10 July 1980.[6][7] Cline claimed that one of the genes in his patients was active six months later, though he never published this data or had it verified[8] and even if he is correct, it’s unlikely it produced any significant beneficial effects treating beta-thalassemia.

After extensive research on animals throughout the 1980s and a 1989 bacterial gene tagging trial on humans, the first gene therapy widely accepted as a success was demonstrated in a trial that started on 14 September 1990, when Ashi DeSilva was treated for ADA-SCID.[9]

The first somatic treatment that produced a permanent genetic change was performed in 1993.[citation needed]

Gene therapy is a way to fix a genetic problem at its source. The polymers are either translated into proteins, interfere with target gene expression, or possibly correct genetic mutations.

The most common form uses DNA that encodes a functional, therapeutic gene to replace a mutated gene. The polymer molecule is packaged within a “vector”, which carries the molecule inside cells.

Early clinical failures led to dismissals of gene therapy. Clinical successes since 2006 regained researchers’ attention, although as of 2014, it was still largely an experimental technique.[10] These include treatment of retinal diseases Leber’s congenital amaurosis[11][12][13][14] and choroideremia,[15] X-linked SCID,[16] ADA-SCID,[17][18] adrenoleukodystrophy,[19] chronic lymphocytic leukemia (CLL),[20] acute lymphocytic leukemia (ALL),[21] multiple myeloma,[22] haemophilia,[18] and Parkinson’s disease.[23] Between 2013 and April 2014, US companies invested over $600 million in the field.[24]

The first commercial gene therapy, Gendicine, was approved in China in 2003 for the treatment of certain cancers.[25] In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia.[26]In 2012 Glybera, a treatment for a rare inherited disorder, became the first treatment to be approved for clinical use in either Europe or the United States after its endorsement by the European Commission.[10][27]

Following early advances in genetic engineering of bacteria, cells, and small animals, scientists started considering how to apply it to medicine. Two main approaches were considered replacing or disrupting defective genes.[28] Scientists focused on diseases caused by single-gene defects, such as cystic fibrosis, haemophilia, muscular dystrophy, thalassemia, and sickle cell anemia. Glybera treats one such disease, caused by a defect in lipoprotein lipase.[27]

DNA must be administered, reach the damaged cells, enter the cell and either express or disrupt a protein.[29] Multiple delivery techniques have been explored. The initial approach incorporated DNA into an engineered virus to deliver the DNA into a chromosome.[30][31] Naked DNA approaches have also been explored, especially in the context of vaccine development.[32]

Generally, efforts focused on administering a gene that causes a needed protein to be expressed. More recently, increased understanding of nuclease function has led to more direct DNA editing, using techniques such as zinc finger nucleases and CRISPR. The vector incorporates genes into chromosomes. The expressed nucleases then knock out and replace genes in the chromosome. As of 2014 these approaches involve removing cells from patients, editing a chromosome and returning the transformed cells to patients.[33]

Gene editing is a potential approach to alter the human genome to treat genetic diseases,[34] viral diseases,[35] and cancer.[36] As of 2016 these approaches were still years from being medicine.[37][38]

Gene therapy may be classified into two types:

In somatic cell gene therapy (SCGT), the therapeutic genes are transferred into any cell other than a gamete, germ cell, gametocyte, or undifferentiated stem cell. Any such modifications affect the individual patient only, and are not inherited by offspring. Somatic gene therapy represents mainstream basic and clinical research, in which therapeutic DNA (either integrated in the genome or as an external episome or plasmid) is used to treat disease.

Over 600 clinical trials utilizing SCGT are underway[when?] in the US. Most focus on severe genetic disorders, including immunodeficiencies, haemophilia, thalassaemia, and cystic fibrosis. Such single gene disorders are good candidates for somatic cell therapy. The complete correction of a genetic disorder or the replacement of multiple genes is not yet possible. Only a few of the trials are in the advanced stages.[39]

In germline gene therapy (GGT), germ cells (sperm or egg cells) are modified by the introduction of functional genes into their genomes. Modifying a germ cell causes all the organism’s cells to contain the modified gene. The change is therefore heritable and passed on to later generations. Australia, Canada, Germany, Israel, Switzerland, and the Netherlands[40] prohibit GGT for application in human beings, for technical and ethical reasons, including insufficient knowledge about possible risks to future generations[40] and higher risks versus SCGT.[41] The US has no federal controls specifically addressing human genetic modification (beyond FDA regulations for therapies in general).[40][42][43][44]

The delivery of DNA into cells can be accomplished by multiple methods. The two major classes are recombinant viruses (sometimes called biological nanoparticles or viral vectors) and naked DNA or DNA complexes (non-viral methods).

In order to replicate, viruses introduce their genetic material into the host cell, tricking the host’s cellular machinery into using it as blueprints for viral proteins. Retroviruses go a stage further by having their genetic material copied into the genome of the host cell. Scientists exploit this by substituting a virus’s genetic material with therapeutic DNA. (The term ‘DNA’ may be an oversimplification, as some viruses contain RNA, and gene therapy could take this form as well.) A number of viruses have been used for human gene therapy, including retroviruses, adenoviruses, herpes simplex, vaccinia, and adeno-associated virus.[4] Like the genetic material (DNA or RNA) in viruses, therapeutic DNA can be designed to simply serve as a temporary blueprint that is degraded naturally or (at least theoretically) to enter the host’s genome, becoming a permanent part of the host’s DNA in infected cells.

Non-viral methods present certain advantages over viral methods, such as large scale production and low host immunogenicity. However, non-viral methods initially produced lower levels of transfection and gene expression, and thus lower therapeutic efficacy. Later technology remedied this deficiency.[citation needed]

Methods for non-viral gene therapy include the injection of naked DNA, electroporation, the gene gun, sonoporation, magnetofection, the use of oligonucleotides, lipoplexes, dendrimers, and inorganic nanoparticles.

Some of the unsolved problems include:

Three patients’ deaths have been reported in gene therapy trials, putting the field under close scrutiny. The first was that of Jesse Gelsinger, who died in 1999 because of immune rejection response.[51] One X-SCID patient died of leukemia in 2003.[9] In 2007, a rheumatoid arthritis patient died from an infection; the subsequent investigation concluded that the death was not related to gene therapy.[52]

In 1972 Friedmann and Roblin authored a paper in Science titled “Gene therapy for human genetic disease?”[53] Rogers (1970) was cited for proposing that exogenous good DNA be used to replace the defective DNA in those who suffer from genetic defects.[54]

In 1984 a retrovirus vector system was designed that could efficiently insert foreign genes into mammalian chromosomes.[55]

The first approved gene therapy clinical research in the US took place on 14 September 1990, at the National Institutes of Health (NIH), under the direction of William French Anderson.[56] Four-year-old Ashanti DeSilva received treatment for a genetic defect that left her with ADA-SCID, a severe immune system deficiency. The defective gene of the patient’s blood cells was replaced by the functional variant. Ashantis immune system was partially restored by the therapy. Production of the missing enzyme was temporarily stimulated, but the new cells with functional genes were not generated. She led a normal life only with the regular injections performed every two months. The effects were successful, but temporary.[57]

Cancer gene therapy was introduced in 1992/93 (Trojan et al. 1993).[58] The treatment of glioblastoma multiforme, the malignant brain tumor whose outcome is always fatal, was done using a vector expressing antisense IGF-I RNA (clinical trial approved by NIH protocolno.1602 November 24, 1993,[59] and by the FDA in 1994). This therapy also represents the beginning of cancer immunogene therapy, a treatment which proves to be effective due to the anti-tumor mechanism of IGF-I antisense, which is related to strong immune and apoptotic phenomena.

In 1992 Claudio Bordignon, working at the Vita-Salute San Raffaele University, performed the first gene therapy procedure using hematopoietic stem cells as vectors to deliver genes intended to correct hereditary diseases.[60] In 2002 this work led to the publication of the first successful gene therapy treatment for adenosine deaminase deficiency (ADA-SCID). The success of a multi-center trial for treating children with SCID (severe combined immune deficiency or “bubble boy” disease) from 2000 and 2002, was questioned when two of the ten children treated at the trial’s Paris center developed a leukemia-like condition. Clinical trials were halted temporarily in 2002, but resumed after regulatory review of the protocol in the US, the United Kingdom, France, Italy, and Germany.[61]

In 1993 Andrew Gobea was born with SCID following prenatal genetic screening. Blood was removed from his mother’s placenta and umbilical cord immediately after birth, to acquire stem cells. The allele that codes for adenosine deaminase (ADA) was obtained and inserted into a retrovirus. Retroviruses and stem cells were mixed, after which the viruses inserted the gene into the stem cell chromosomes. Stem cells containing the working ADA gene were injected into Andrew’s blood. Injections of the ADA enzyme were also given weekly. For four years T cells (white blood cells), produced by stem cells, made ADA enzymes using the ADA gene. After four years more treatment was needed.[62]

Jesse Gelsinger’s death in 1999 impeded gene therapy research in the US.[63][64] As a result, the FDA suspended several clinical trials pending the reevaluation of ethical and procedural practices.[65]

The modified cancer gene therapy strategy of antisense IGF-I RNA (NIH n 1602)[59] using antisense / triple helix anti-IGF-I approach was registered in 2002 by Wiley gene therapy clinical trial – n 635 and 636. The approach has shown promising results in the treatment of six different malignant tumors: glioblastoma, cancers of liver, colon, prostate, uterus, and ovary (Collaborative NATO Science Programme on Gene Therapy USA, France, Poland n LST 980517 conducted by J. Trojan) (Trojan et al., 2012). This anti-gene antisense/triple helix therapy has proven to be efficient, due to the mechanism stopping simultaneously IGF-I expression on translation and transcription levels, strengthening anti-tumor immune and apoptotic phenomena.

Sickle-cell disease can be treated in mice.[66] The mice which have essentially the same defect that causes human cases used a viral vector to induce production of fetal hemoglobin (HbF), which normally ceases to be produced shortly after birth. In humans, the use of hydroxyurea to stimulate the production of HbF temporarily alleviates sickle cell symptoms. The researchers demonstrated this treatment to be a more permanent means to increase therapeutic HbF production.[67]

A new gene therapy approach repaired errors in messenger RNA derived from defective genes. This technique has the potential to treat thalassaemia, cystic fibrosis and some cancers.[68]

Researchers created liposomes 25 nanometers across that can carry therapeutic DNA through pores in the nuclear membrane.[69]

In 2003 a research team inserted genes into the brain for the first time. They used liposomes coated in a polymer called polyethylene glycol, which unlike viral vectors, are small enough to cross the bloodbrain barrier.[70]

Short pieces of double-stranded RNA (short, interfering RNAs or siRNAs) are used by cells to degrade RNA of a particular sequence. If a siRNA is designed to match the RNA copied from a faulty gene, then the abnormal protein product of that gene will not be produced.[71]

Gendicine is a cancer gene therapy that delivers the tumor suppressor gene p53 using an engineered adenovirus. In 2003, it was approved in China for the treatment of head and neck squamous cell carcinoma.[25]

In March researchers announced the successful use of gene therapy to treat two adult patients for X-linked chronic granulomatous disease, a disease which affects myeloid cells and damages the immune system. The study is the first to show that gene therapy can treat the myeloid system.[72]

In May a team reported a way to prevent the immune system from rejecting a newly delivered gene.[73] Similar to organ transplantation, gene therapy has been plagued by this problem. The immune system normally recognizes the new gene as foreign and rejects the cells carrying it. The research utilized a newly uncovered network of genes regulated by molecules known as microRNAs. This natural function selectively obscured their therapeutic gene in immune system cells and protected it from discovery. Mice infected with the gene containing an immune-cell microRNA target sequence did not reject the gene.

In August scientists successfully treated metastatic melanoma in two patients using killer T cells genetically retargeted to attack the cancer cells.[74]

In November researchers reported on the use of VRX496, a gene-based immunotherapy for the treatment of HIV that uses a lentiviral vector to deliver an antisense gene against the HIV envelope. In a phase I clinical trial, five subjects with chronic HIV infection who had failed to respond to at least two antiretroviral regimens were treated. A single intravenous infusion of autologous CD4 T cells genetically modified with VRX496 was well tolerated. All patients had stable or decreased viral load; four of the five patients had stable or increased CD4 T cell counts. All five patients had stable or increased immune response to HIV antigens and other pathogens. This was the first evaluation of a lentiviral vector administered in a US human clinical trial.[75][76]

In May researchers announced the first gene therapy trial for inherited retinal disease. The first operation was carried out on a 23-year-old British male, Robert Johnson, in early 2007.[77]

Leber’s congenital amaurosis is an inherited blinding disease caused by mutations in the RPE65 gene. The results of a small clinical trial in children were published in April.[11] Delivery of recombinant adeno-associated virus (AAV) carrying RPE65 yielded positive results. In May two more groups reported positive results in independent clinical trials using gene therapy to treat the condition. In all three clinical trials, patients recovered functional vision without apparent side-effects.[11][12][13][14]

In September researchers were able to give trichromatic vision to squirrel monkeys.[78] In November 2009, researchers halted a fatal genetic disorder called adrenoleukodystrophy in two children using a lentivirus vector to deliver a functioning version of ABCD1, the gene that is mutated in the disorder.[79]

An April paper reported that gene therapy addressed achromatopsia (color blindness) in dogs by targeting cone photoreceptors. Cone function and day vision were restored for at least 33 months in two young specimens. The therapy was less efficient for older dogs.[80]

In September it was announced that an 18-year-old male patient in France with beta-thalassemia major had been successfully treated.[81] Beta-thalassemia major is an inherited blood disease in which beta haemoglobin is missing and patients are dependent on regular lifelong blood transfusions.[82] The technique used a lentiviral vector to transduce the human -globin gene into purified blood and marrow cells obtained from the patient in June 2007.[83] The patient’s haemoglobin levels were stable at 9 to 10 g/dL. About a third of the hemoglobin contained the form introduced by the viral vector and blood transfusions were not needed.[83][84] Further clinical trials were planned.[85] Bone marrow transplants are the only cure for thalassemia, but 75% of patients do not find a matching donor.[84]

Cancer immunogene therapy using modified antigene, antisense/triple helix approach was introduced in South America in 2010/11 in La Sabana University, Bogota (Ethical Committee 14 December 2010, no P-004-10). Considering the ethical aspect of gene diagnostic and gene therapy targeting IGF-I, the IGF-I expressing tumors i.e. lung and epidermis cancers were treated (Trojan et al. 2016).[86][87]

In 2007 and 2008, a man (Timothy Ray Brown) was cured of HIV by repeated hematopoietic stem cell transplantation (see also allogeneic stem cell transplantation, allogeneic bone marrow transplantation, allotransplantation) with double-delta-32 mutation which disables the CCR5 receptor. This cure was accepted by the medical community in 2011.[88] It required complete ablation of existing bone marrow, which is very debilitating.

In August two of three subjects of a pilot study were confirmed to have been cured from chronic lymphocytic leukemia (CLL). The therapy used genetically modified T cells to attack cells that expressed the CD19 protein to fight the disease.[20] In 2013, the researchers announced that 26 of 59 patients had achieved complete remission and the original patient had remained tumor-free.[89]

Human HGF plasmid DNA therapy of cardiomyocytes is being examined as a potential treatment for coronary artery disease as well as treatment for the damage that occurs to the heart after myocardial infarction.[90][91]

In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia; it delivers the gene encoding for VEGF.[92][26] Neovasculogen is a plasmid encoding the CMV promoter and the 165 amino acid form of VEGF.[93][94]

The FDA approved Phase 1 clinical trials on thalassemia major patients in the US for 10 participants in July.[95] The study was expected to continue until 2015.[85]

In July 2012, the European Medicines Agency recommended approval of a gene therapy treatment for the first time in either Europe or the United States. The treatment used Alipogene tiparvovec (Glybera) to compensate for lipoprotein lipase deficiency, which can cause severe pancreatitis.[96] The recommendation was endorsed by the European Commission in November 2012[10][27][97][98] and commercial rollout began in late 2014.[99] Alipogene tiparvovec was expected to cost around $1.6 million per treatment in 2012,[100] revised to $1 million in 2015,[101] making it the most expensive medicine in the world at the time.[102] As of 2016, only one person had been treated with drug.[103]

In December 2012, it was reported that 10 of 13 patients with multiple myeloma were in remission “or very close to it” three months after being injected with a treatment involving genetically engineered T cells to target proteins NY-ESO-1 and LAGE-1, which exist only on cancerous myeloma cells.[22]

In March researchers reported that three of five adult subjects who had acute lymphocytic leukemia (ALL) had been in remission for five months to two years after being treated with genetically modified T cells which attacked cells with CD19 genes on their surface, i.e. all B-cells, cancerous or not. The researchers believed that the patients’ immune systems would make normal T-cells and B-cells after a couple of months. They were also given bone marrow. One patient relapsed and died and one died of a blood clot unrelated to the disease.[21]

Following encouraging Phase 1 trials, in April, researchers announced they were starting Phase 2 clinical trials (called CUPID2 and SERCA-LVAD) on 250 patients[104] at several hospitals to combat heart disease. The therapy was designed to increase the levels of SERCA2, a protein in heart muscles, improving muscle function.[105] The FDA granted this a Breakthrough Therapy Designation to accelerate the trial and approval process.[106] In 2016 it was reported that no improvement was found from the CUPID 2 trial.[107]

In July researchers reported promising results for six children with two severe hereditary diseases had been treated with a partially deactivated lentivirus to replace a faulty gene and after 732 months. Three of the children had metachromatic leukodystrophy, which causes children to lose cognitive and motor skills.[108] The other children had Wiskott-Aldrich syndrome, which leaves them to open to infection, autoimmune diseases, and cancer.[109] Follow up trials with gene therapy on another six children with Wiskott-Aldrich syndrome were also reported as promising.[110][111]

In October researchers reported that two children born with adenosine deaminase severe combined immunodeficiency disease (ADA-SCID) had been treated with genetically engineered stem cells 18 months previously and that their immune systems were showing signs of full recovery. Another three children were making progress.[18] In 2014 a further 18 children with ADA-SCID were cured by gene therapy.[112] ADA-SCID children have no functioning immune system and are sometimes known as “bubble children.”[18]

Also in October researchers reported that they had treated six hemophilia sufferers in early 2011 using an adeno-associated virus. Over two years later all six were producing clotting factor.[18][113]

In January researchers reported that six choroideremia patients had been treated with adeno-associated virus with a copy of REP1. Over a six-month to two-year period all had improved their sight.[114][115] By 2016, 32 patients had been treated with positive results and researchers were hopeful the treatment would be long-lasting.[15] Choroideremia is an inherited genetic eye disease with no approved treatment, leading to loss of sight.

In March researchers reported that 12 HIV patients had been treated since 2009 in a trial with a genetically engineered virus with a rare mutation (CCR5 deficiency) known to protect against HIV with promising results.[116][117]

Clinical trials of gene therapy for sickle cell disease were started in 2014.[118][119] There is a need for high quality randomised controlled trials assessing the risks and benefits involved with gene therapy for people with sickle cell disease.[120]

In February LentiGlobin BB305, a gene therapy treatment undergoing clinical trials for treatment of beta thalassemia gained FDA “breakthrough” status after several patients were able to forgo the frequent blood transfusions usually required to treat the disease.[121]

In March researchers delivered a recombinant gene encoding a broadly neutralizing antibody into monkeys infected with simian HIV; the monkeys’ cells produced the antibody, which cleared them of HIV. The technique is named immunoprophylaxis by gene transfer (IGT). Animal tests for antibodies to ebola, malaria, influenza, and hepatitis were underway.[122][123]

In March, scientists, including an inventor of CRISPR, Jennifer Doudna, urged a worldwide moratorium on germline gene therapy, writing “scientists should avoid even attempting, in lax jurisdictions, germline genome modification for clinical application in humans” until the full implications “are discussed among scientific and governmental organizations”.[124][125][126][127]

In October, researchers announced that they had treated a baby girl, Layla Richards, with an experimental treatment using donor T-cells genetically engineered using TALEN to attack cancer cells. One year after the treatment she was still free of her cancer (a highly aggressive form of acute lymphoblastic leukaemia [ALL]).[128] Children with highly aggressive ALL normally have a very poor prognosis and Layla’s disease had been regarded as terminal before the treatment.[129]

In December, scientists of major world academies called for a moratorium on inheritable human genome edits, including those related to CRISPR-Cas9 technologies[130] but that basic research including embryo gene editing should continue.[131]

In April the Committee for Medicinal Products for Human Use of the European Medicines Agency endorsed a gene therapy treatment called Strimvelis[132][133] and the European Commission approved it in June.[134] This treats children born with adenosine deaminase deficiency and who have no functioning immune system. This was the second gene therapy treatment to be approved in Europe.[135]

In October, Chinese scientists reported they had started a trial to genetically modify T-cells from 10 adult patients with lung cancer and reinject the modified T-cells back into their bodies to attack the cancer cells. The T-cells had the PD-1 protein (which stops or slows the immune response) removed using CRISPR-Cas9.[136][137]

A 2016 Cochrane systematic review looking at data from four trials on topical cystic fibrosis transmembrane conductance regulator (CFTR) gene therapy does not support its clinical use as a mist inhaled into the lungs to treat cystic fibrosis patients with lung infections. One of the four trials did find weak evidence that liposome-based CFTR gene transfer therapy may lead to a small respiratory improvement for people with CF. This weak evidence is not enough to make a clinical recommendation for routine CFTR gene therapy.[138]

In February Kite Pharma announced results from a clinical trial of CAR-T cells in around a hundred people with advanced Non-Hodgkin lymphoma.[139]

In March, French scientists reported on clinical research of gene therapy to treat sickle-cell disease.[140]

In August, the FDA approved tisagenlecleucel for acute lymphoblastic leukemia.[141] Tisagenlecleucel is an adoptive cell transfer therapy for B-cell acute lymphoblastic leukemia; T cells from a person with cancer are removed, genetically engineered to make a specific T-cell receptor (a chimeric T cell receptor, or “CAR-T”) that reacts to the cancer, and are administered back to the person. The T cells are engineered to target a protein called CD19 that is common on B cells. This is the first form of gene therapy to be approved in the United States. In October, a similar therapy called axicabtagene ciloleucel was approved for non-Hodgkin lymphoma.[142]

In December the results of using an adeno-associated virus with blood clotting factor VIII to treat nine haemophilia A patients were published. Six of the seven patients on the high dose regime increased the level of the blood clotting VIII to normal levels. The low and medium dose regimes had no effect on the patient’s blood clotting levels.[143][144]

In December, the FDA approved Luxturna, the first in vivo gene therapy, for the treatment of blindness due to Leber’s congenital amaurosis.[145] The price of this treatment was 850,000 US dollars for both eyes.[146][147]

Speculated uses for gene therapy include:

Gene therapy techniques have the potential to provide alternative treatments for those with infertility. Recently, successful experimentation on mice has proven that fertility can be restored by using the gene therapy method, CRISPR.[148] Spermatogenical stem cells from another organism were transplanted into the testes of an infertile male mouse. The stem cells re-established spermatogenesis and fertility.[149]

Athletes might adopt gene therapy technologies to improve their performance.[150] Gene doping is not known to occur, but multiple gene therapies may have such effects. Kayser et al. argue that gene doping could level the playing field if all athletes receive equal access. Critics claim that any therapeutic intervention for non-therapeutic/enhancement purposes compromises the ethical foundations of medicine and sports.[151]

Genetic engineering could be used to cure diseases, but also to change physical appearance, metabolism, and even improve physical capabilities and mental faculties such as memory and intelligence. Ethical claims about germline engineering include beliefs that every fetus has a right to remain genetically unmodified, that parents hold the right to genetically modify their offspring, and that every child has the right to be born free of preventable diseases.[152][153][154] For parents, genetic engineering could be seen as another child enhancement technique to add to diet, exercise, education, training, cosmetics, and plastic surgery.[155][156] Another theorist claims that moral concerns limit but do not prohibit germline engineering.[157]

Possible regulatory schemes include a complete ban, provision to everyone, or professional self-regulation. The American Medical Associations Council on Ethical and Judicial Affairs stated that “genetic interventions to enhance traits should be considered permissible only in severely restricted situations: (1) clear and meaningful benefits to the fetus or child; (2) no trade-off with other characteristics or traits; and (3) equal access to the genetic technology, irrespective of income or other socioeconomic characteristics.”[158]

As early in the history of biotechnology as 1990, there have been scientists opposed to attempts to modify the human germline using these new tools,[159] and such concerns have continued as technology progressed.[160][161] With the advent of new techniques like CRISPR, in March 2015 a group of scientists urged a worldwide moratorium on clinical use of gene editing technologies to edit the human genome in a way that can be inherited.[124][125][126][127] In April 2015, researchers sparked controversy when they reported results of basic research to edit the DNA of non-viable human embryos using CRISPR.[148][162] A committee of the American National Academy of Sciences and National Academy of Medicine gave qualified support to human genome editing in 2017[163][164] once answers have been found to safety and efficiency problems “but only for serious conditions under stringent oversight.”[165]

Regulations covering genetic modification are part of general guidelines about human-involved biomedical research. There are no international treaties which are legally binding in this area, but there are recommendations for national laws from various bodies.

The Helsinki Declaration (Ethical Principles for Medical Research Involving Human Subjects) was amended by the World Medical Association’s General Assembly in 2008. This document provides principles physicians and researchers must consider when involving humans as research subjects. The Statement on Gene Therapy Research initiated by the Human Genome Organization (HUGO) in 2001 provides a legal baseline for all countries. HUGOs document emphasizes human freedom and adherence to human rights, and offers recommendations for somatic gene therapy, including the importance of recognizing public concerns about such research.[166]

No federal legislation lays out protocols or restrictions about human genetic engineering. This subject is governed by overlapping regulations from local and federal agencies, including the Department of Health and Human Services, the FDA and NIH’s Recombinant DNA Advisory Committee. Researchers seeking federal funds for an investigational new drug application, (commonly the case for somatic human genetic engineering,) must obey international and federal guidelines for the protection of human subjects.[167]

NIH serves as the main gene therapy regulator for federally funded research. Privately funded research is advised to follow these regulations. NIH provides funding for research that develops or enhances genetic engineering techniques and to evaluate the ethics and quality in current research. The NIH maintains a mandatory registry of human genetic engineering research protocols that includes all federally funded projects.

An NIH advisory committee published a set of guidelines on gene manipulation.[168] The guidelines discuss lab safety as well as human test subjects and various experimental types that involve genetic changes. Several sections specifically pertain to human genetic engineering, including Section III-C-1. This section describes required review processes and other aspects when seeking approval to begin clinical research involving genetic transfer into a human patient.[169] The protocol for a gene therapy clinical trial must be approved by the NIH’s Recombinant DNA Advisory Committee prior to any clinical trial beginning; this is different from any other kind of clinical trial.[168]

As with other kinds of drugs, the FDA regulates the quality and safety of gene therapy products and supervises how these products are used clinically. Therapeutic alteration of the human genome falls under the same regulatory requirements as any other medical treatment. Research involving human subjects, such as clinical trials, must be reviewed and approved by the FDA and an Institutional Review Board.[170][171]

Gene therapy is the basis for the plotline of the film I Am Legend[172] and the TV show Will Gene Therapy Change the Human Race?.[173] In 1994, gene therapy was a plot element in The Erlenmeyer Flask, The X-Files’ first season finale. It is also used in Stargate as a means of allowing humans to use Ancient technology.[174]

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Gene therapy – Wikipedia

Gene therapy – Mayo Clinic

Overview

Gene therapy involves altering the genes inside your body’s cells in an effort to treat or stop disease.

Genes contain your DNA the code that controls much of your body’s form and function, from making you grow taller to regulating your body systems. Genes that don’t work properly can cause disease.

Gene therapy replaces a faulty gene or adds a new gene in an attempt to cure disease or improve your body’s ability to fight disease. Gene therapy holds promise for treating a wide range of diseases, such as cancer, cystic fibrosis, heart disease, diabetes, hemophilia and AIDS.

Researchers are still studying how and when to use gene therapy. Currently, in the United States, gene therapy is available only as part of a clinical trial.

Gene therapy is used to correct defective genes in order to cure a disease or help your body better fight disease.

Researchers are investigating several ways to do this, including:

Gene therapy has some potential risks. A gene can’t easily be inserted directly into your cells. Rather, it usually has to be delivered using a carrier, called a vector.

The most common gene therapy vectors are viruses because they can recognize certain cells and carry genetic material into the cells’ genes. Researchers remove the original disease-causing genes from the viruses, replacing them with the genes needed to stop disease.

This technique presents the following risks:

The gene therapy clinical trials underway in the U.S. are closely monitored by the Food and Drug Administration and the National Institutes of Health to ensure that patient safety issues are a top priority during research.

Currently, the only way for you to receive gene therapy is to participate in a clinical trial. Clinical trials are research studies that help doctors determine whether a gene therapy approach is safe for people. They also help doctors understand the effects of gene therapy on the body.

Your specific procedure will depend on the disease you have and the type of gene therapy being used.

For example, in one type of gene therapy:

Viruses aren’t the only vectors that can be used to carry altered genes into your body’s cells. Other vectors being studied in clinical trials include:

The possibilities of gene therapy hold much promise. Clinical trials of gene therapy in people have shown some success in treating certain diseases, such as:

But several significant barriers stand in the way of gene therapy becoming a reliable form of treatment, including:

Gene therapy continues to be a very important and active area of research aimed at developing new, effective treatments for a variety of diseases.

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.

Dec. 29, 2017

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Gene therapy – Mayo Clinic

The Epic Relation Between Bitcoin and the Stock Market

Bitcoin Prices Are Less Independent Than You Think
Inside the world of cryptocurrencies, some truths go unquestioned: 1) centralization is terrible, 2) fixed money supplies are great, 3) cryptocurrencies are uncorrelated from stocks.

The last “truth” is now in question.

Many analysts, myself included, have raised questions about Bitcoin following the stock market before, but none of us made the case as strongly as Forbes contributor Clem Chambers.

Chambers recently used intraday trade charts to show that Bitcoin prices often follow the same patterns as the Dow Jones Index. (Source: “.

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The Epic Relation Between Bitcoin and the Stock Market

Cryptocurrency News: What You Need to Know This Week

Cryptocurrency News
Cryptocurrencies traded sideways since our last report on cryptos. However, I noticed something interesting when playing around with Yahoo! Finance’s cryptocurrency screener: There are profitable pockets in this market.

Incidentally, Yahoo’s screener is far superior to the one on CoinMarketCap, so if you’re looking to compare digital assets, I highly recommend it.

But let’s get back to my epiphany.

In the last month, at one point or another, most crypto assets on our favorites list saw double-digit increases. It’s true that each upswing was followed by a hard crash, but investors who rode the trend would have made a.

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Cryptocurrency News: What You Need to Know This Week

Ripple Price Forecast: XRP vs SWIFT, SEC Updates, and More

Ripple vs SWIFT: The War Begins
While most criticisms of XRP do nothing to curb my bullish Ripple price forecast, there is one obstacle that nags at my conscience. Its name is SWIFT.

The Society for Worldwide Interbank Financial Telecommunication (SWIFT) is the king of international payments.

It coordinates wire transfers across 11,000 banks in more than 200 countries and territories, meaning that in order for XRP prices to ascend to $10.00, Ripple needs to launch a successful coup. That is, and always has been, an unwritten part of Ripple’s story.

We’ve seen a lot of progress on that score. In the last three years, Ripple wooed more than 100 financial firms onto its.

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Ripple Price Forecast: XRP vs SWIFT, SEC Updates, and More

Ripple Price Prediction: xRapid Shows Success, But SEC Still Holds Power

XRP Prices Hang in the Balance
Ripple bears like to claim that XRP “serves no purpose” in its technology, but recent success with the “xRapid” software says otherwise. That—plus the continual “Is XRP a security?” debate—drove Ripple prices round and round in circles last week.

I see these two forces working in opposite directions.

Investors should be happy that xRapid is providing genuine benefits to businesses that dared to take a chance on XRP. But does it matter if the U.S. Securities & Exchange Commission (SEC) designates XRP a security?
xRapid Success
For the uninitiated, Ripple has multiple offerings. One is “xCurrent,” a.

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Ripple Price Prediction: xRapid Shows Success, But SEC Still Holds Power

Cryptocurrency News: This Week on Bitfinex, Tether, Coinbase, & More

Cryptocurrency News
On the whole, cryptocurrency prices are down from our previous report on cryptos, with the market slipping on news of an exchange being hacked and a report about Bitcoin manipulation.

However, there have been two bright spots: 1) an official from the U.S. Securities and Exchange Commission (SEC) said that Ethereum is not a security, and 2) Coinbase is expanding its selection of tokens.

Let’s start with the good news.
SEC Says ETH Is Not a Security
Investors have some reason to cheer this week. A high-ranking SEC official told attendees of the Yahoo! All Markets Summit: Crypto that Ethereum and Bitcoin are not.

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Cryptocurrency News: This Week on Bitfinex, Tether, Coinbase, & More

Ethereum Price Forecast: Big Corporate Moves Could Bolster ETH Prices

Crypto Rally Slows Down
As I write this report, cryptocurrency prices are in the middle of a vicious tug of war between the bulls and the bears. And the bears are winning right now.

Most, if not all, of our favorite cryptocurrencies trended down over the last seven days, erasing the progress they made in earlier weeks.

Short-term volatility is completely overtaking the market, making it tough for existing holders of crypto assets.

But…

If you’re someone who is looking to enter the market, a sell-off is exactly the right time. How many times have I heard investors say, “If I had bought Bitcoin two years ago, I would have made [insert insane profits.

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Ethereum Price Forecast: Big Corporate Moves Could Bolster ETH Prices

Cryptocurrency News: XRP Validators, Malta, and Practical Tokens

Cryptocurrency News & Market Summary
Investors finally saw some light at the end of the tunnel last week, with cryptos soaring across the board. No one quite knows what kicked off the rally—as it could have been any of the stories we discuss below—but the net result was positive.

Of course, prices won’t stay on this rocket ride forever. I expect to see a resurgence of volatility in short order, because the market is moving as a single unit. Everything is rising in tandem.

This tells me that investors are simply “buying the dip” rather than identifying which cryptos have enough real-world value to outlive the crash.

So if you want to know when.

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Cryptocurrency News: XRP Validators, Malta, and Practical Tokens

Cryptocurrency News: Looking Past the Bithumb Crypto Hack

Another Crypto Hack Derails Recovery
Since our last report, hackers broke into yet another cryptocurrency exchange. This time the target was Bithumb, a Korean exchange known for high-flying prices and ultra-active traders.

While the hackers made off with approximately $31.5 million in funds, the exchange is working with relevant authorities to return the stolen tokens to their respective owners. In the event that some is still missing, the exchange will cover the losses. (Source: “Bithumb Working With Other Crypto Exchanges to Recover Hacked Funds,”.

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Cryptocurrency News: Looking Past the Bithumb Crypto Hack

Cryptocurrency Price Forecast: Trust Is Growing, But Prices Are Falling

Trust Is Growing…
Before we get to this week’s cryptocurrency news, analysis, and our cryptocurrency price forecast, I want to share an experience from this past week. I was at home watching the NBA playoffs, trying to ignore the commercials, when a strange advertisement caught my eye.

It followed a tomato from its birth on the vine to its end on the dinner table (where it was served as a bolognese sauce), and a diamond from its dusty beginnings to when it sparkled atop an engagement ring.

The voiceover said: “This is a shipment passed 200 times, transparently tracked from port to port. This is the IBM blockchain.”

Let that sink in—IBM.

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Cryptocurrency Price Forecast: Trust Is Growing, But Prices Are Falling