Nov 19, 2021

Spark Therapeutics announced updated data from a phase 1/2 clinical trial of SPK-8011, the company’s investigational gene therapy for hemophilia A. 

Administered via a one-time intravenous infusion, SPK-8011 is designed to prompt the production of therapeutic levels of the factor VIII (FVIII) protein that is deficient in individuals with hemophilia A. Spark’s proprietary bioengineered adeno-associated virus (AAV) vectors carry the genetic codes that help generate FVIII. The approach being tested in this trial uses a modified novel AAV vector genome (vg) to deliver the corrected FVIII gene into liver cells where the protein is normally generated.

A total of 18 participants in the trial have received a single administration of SPK-8011 in four dose groups, ranging from 5×10 vg/per kilogram body weight (vg/kg) 11 to 2×1012 vg/kg. According to a new press release, a median efficacy follow-up of 33.4 months (range 3.7-47.6) showed that 16 of 18 study participants had sustained factor VIII, resulting in a reduction in bleeding episodes and allowing for a cessation of prophylaxis. 

The updated analysis (cutoff May 3, 2021) of all 18 study participants demonstrated a 91.5% reduction in annualized bleed rate and a 96.4% reduction in annualized number of FVIII infusions.

The Spark update also included safety data, which encompassed a median safety observation period of 36.6 months (range, 5.5 to 50.3). In all, 33 treatment-related adverse events (AEs) occurred in eight participants of which 17 were vector-related, including one serious AE, while 16 were associated with the use of corticosteroids. Two participants lost all FVIII expression due to a cellular immune response against the capsid, the AAV’s protein shell. The remaining 16 participants maintained FVIII expression, of which 12 were followed for more than two years and “demonstrated no apparent decrease in one-stage FVIII activity over time.”

These data were recently published on November 18th in the New England Journal of Medicine.

“We are thrilled that the New England Journal of Medicine chose to publish data from our Phase 1/2 study of investigational SPK-8011 and highlight its potential for patients living with hemophilia A,” said Gallia Levy, MD, PhD, Chief Medical Officer, Spark Therapeutics. “This Phase 1/2 study for SPK-8011 demonstrates our commitment to following the science to develop gene therapies for hemophilia A that demonstrate safety, predictability, efficacy, and durability at the lowest effective dose and with an optimal immunomodulatory regimen.”

Source: Spark press release dated November 17, 2021

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