After rattling investors with early signs of an immune reaction in a couple of cases as well as an unexpected infusion for a suspected knee bleed, Spark Therapeutics $ONCE says that its early Phase I/II study for its hemophilia B gene therapy is staying on track, slashing the rate of annual infusions and the bleed rate among the 10 patients on the pioneering therapy SPK-9001.

The annual infusion rate has new dropped 99%, down to a mean of 1 compared to 67.5 ahead of treatment. Five of the 10 are now past the one-year mark since their treatment, with no bleeding issues. The group of 10 posted an average bleed rate of 0.4 compared to 11.1 ahead of once-and-done therapy.

Singling out the first patient, whos now past the 18-month mark, researchers say hes had zero bleeds with no Factor IX infusions. Both cases of elevated liver enzymes indicating an immune response to the delivery vector were resolved with steroids and neither have had bleeds or the need for infusions.

Spark has now accumulated close to 10 years of patient responses to its therapy, an important first step in laying out the potential for gene therapy to end hemophilia.

The latest update arrived at a scientific conference in Berlin marked by the dramatic showdown between Shire and its rival Roche, which fielded more newly contested boasts about its would-be hemophilia blockbuster emicizumab. Alnylam and Sanofi also stepped up with a promising look at the latest Phase II data on their RNAi approach underscoring some significant gains in the field for a variety of new approaches to the rare blood disorder.

We continue to be encouraged by the SPK-9001 clinical trial results observed to date, with all participants having discontinued routine infusions of factor IX concentrates, said Katherine A. High, M.D., president and chief scientific officer at Spark Therapeutics. The growing body of data showing a sustained response is a promising sign for this investigational hemophilia B gene therapy program.

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Pioneering gene therapy patients stay on track, boosting Spark's ... - Endpoints News