Spark Therapeutics and Pfizer Announce Longer-term Preliminary Data Showing Consistent and Sustained Factor IX Levels in Hemophilia B

Note: The following is edited from a press release from Spark Therapeutics. Read the full press release in its entirety here.

Spark Therapeutics and Pfizer Inc. announced on Dec. 11, 2017, with a cumulative follow-up of more than 13 patient years of observation, all 11 participants in the ongoing Phase 1/2 clinical trial of investigational SPK-9001 for the treatment of patients with hemophilia B had discontinued routine infusions of factor IX concentrates and shown sustained steady-state factor IX activity levels with no serious adverse events, thrombotic events or factor IX inhibitors observed. Based on individual participant history for the year prior to the study, the overall annualized bleeding rate (ABR) was reduced by 97 percent (calculated based on data after week four; 95 percent based on data after infusion) to a mean of 0.3 (0.5) annual bleeds, compared to a mean of 10.5 bleeds annually before SPK-9001 administration. Overall annualized infusion rate (AIR) was reduced 99 percent (calculated based on data after week four; 97 percent based on data after infusion) to a mean of 0.8 (1.7) annual infusions, compared to a mean of 62.5 infusions per year before SPK-9001 administration. Data on all 11 participants were presented by Lindsey A. George, M.D., attending physician in the Division of Hematology at Children’s Hospital of Philadelphia and principal investigator of the trial, at the 59th American Society of Hematology (ASH) Annual Meeting and Exposition in Atlanta.
The New England Journal of Medicine has published interim data as of July 25, 2017.