Gene therapy maintains normal FVIII levels long-term

Table 2:  FVIII levels (%) of 4e13 vg/kg dose patients* by visit (n=6)

*Weeks were windowed by +/- 2 weeks

** Bolded numbers are in the mild range of FVIII as defined by the World Federation of Hemophilia

ABR and FVIII infusions

Six of the 7 patients in the 6e13 vg/kg cohort were on pre-study prophylaxis.

After these patients received a single dose BMN270 and reached a FVIII level above 5%, the mean ABR was reduced by 97%, from 16.3 to 0.5. The median ABR for these patients was reduced from 16.5 to 0.

The mean annualized FVIII infusions were reduced by 94%, from 136.7 to 8.5. And the median annualized FVIII infusions were reduced from 138.5 to 0.

All 6 patients in the 4e13 vg/kg dose cohort were on pre-study prophylaxis.

The mean ABR was reduced from 12.2 pre-study to 0 after they reached an FVIII level above 5%. The median ABR for these patients was reduced from 8.0 to 0.

The mean annualized FVIII infusions were reduced from 144.2 to 0. The median annualized FVIII infusions were reduced from 155.5 to 0.

“Patients at the 2 highest doses have stopped prophylactic treatment and, to date, bleeds have effectively been eliminated,” Dr Pasi noted.

Based on these results, BioMarin is planning a phase 3 registrational study of BMN 270. The study will likely include fewer than 100 patients and collect data for no longer than a year after a single dose of BMN 270, with subsequent long-term follow-up.

The company is moving the 6e13 vg/kg dose forward but will consider doing an additional study with the 4e13 vg/kg dose at a later date.