BioMarin gene therapy shows durable long-term effect in hemophilia A study

Updated data from an open-label Phase 1/2 clinical trial evaluating BioMarin Pharmaceutical’s (BMRN +1.9%) gene therapy valoctocogene roxaparvovec in patients with severe hemophilia A showed a sustained benefit from a single administration. The results were presented at the World Federation of Hemophilia Virtual Summit.

At data cutoff on April 8, six participants who were previously on Factor VIII (FVIII) prophylaxis in the 6e13 vg/kg cohort experienced sustained reductions in bleeding episodes that required FVIII infusions. In the year prior to receiving the gene therapy, the mean annualized bleed rate (ABR) was 16.3 while the median was 16.5. During the four years post treatment, cumulative mean ABR dropped 95% to 0.8. In year 4, mean ABR was 1.3 while the median was zero. FVIII usage dropped 96% to 5.4 infusions per year cumulatively over four years compared to 135.6 infusions/year at baseline. Six of seven subjects were bleed-free in year 4 and all remain off FVIII prophylaxis therapy.

At the end of year 4, mean FVIII activity levels were 24.2 IU/dL or 35.4 IU/dL, depending on the test used. Median FVIII levels were 16.4 IU/dL or 23.4 IU/dL (normal range is 50 – 150 IU/dL. Hemophilia A is defined as levels below 50).

Six patients in the 4e13 vg/kg cohort experienced similar benefits. In the year prior to treatment, mean and median ABR were 12.2 and 8.0, respectively. After treatment, cumulative mean ABR dropped 93% to 0.9 during the three-year follow-up period. During year 3, mean ABR was 0.5 and median was zero. Four of six participants were bleed-free and five of six experienced no spontaneous bleeds. Mean Factor VIII usage dropped 96% to 5.7 infusion per year over three years from a baseline of 142.8 infusions per year.

At the end of year 3, mean FVIII levels were 9.9 IU/dL or 14.9 IU/dL depending on the test used. Median FVIII levels were 7.9 IU/dL or 12.3 IU/dL.

The company will host a webinar today at 5:00 pm ET to discuss the data.

https://seekingalpha.com/news/3583790-biomarin-gene-therapy-shows-durable-long-term-effect-in-hemophilia-study