Dr. John Pasi, Centre Director at the Royal London Haemophilia Centre, presented 4-year follow-up data on Biomarin Pharmaceutical’s Phase 1 /2 gene therapy trial of valoctocogene roxaparvovec (valrox) for hemophilia A, using the AAV5 vector.
Seven patients had received the highest dose: 7 X 1013 vector genomes per kilogram of body weight (vg/kg). They experienced an overall 96% decrease in FVIII usage and a 95% decrease in annual bleeding rate. Six of the seven were bleed-free in Year 4 following infusion. No one has required prophylaxis.
Levels of factor VIII expression have gradually declined over the four years, albeit more slowly in Year 4. Most people are in the mild range (5-40%); the mean FVIII level is 24%.
Data on a larger cohort at the same dose in the Phase 3 trial will soon be released. Biomarin has submitted marketing applications to the FDA and a decision is expected in 2020.