BioMarin's gene therapy valoctocogene roxaparvovec shows continued early promise in haemophilia A

BioMarin Pharmaceutical presented updated results from a Phase I/II study of valoctocogene roxaparvovec, with data showing that 11 of 13 patients with haemophilia A who received a single infusion of the experimental gene therapy achieved normal or near-normal factor VIII levels. The results were reported at the American Society of Hematology (ASH) annual meeting.

Lead researcher K. John Pasi remarked "the clinical data to date for this investigational gene therapy exceeded our expectations, in terms of increasing factor VIII levels and reducing the annualised bleed rate." Pasi added "this clinical result has the potential to improve the lives of patients who now must infuse themselves with factor VIII as often as every other day."

BioMarin provided an update on the 4e13 vg/kg dose studied in the trial in October and on the 6e13 vg/kg dose earlier in the year. At ASH, the company reported the most current data, as of November 16 cut off, including 78 weeks of data for the 6e13 vg/kg dose and 48 weeks of data for the 4e13 vg/kg dose. 

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The company noted for the 4e13 vg/kg dose group, since the last update, the three patients with the longest follow-up have factor VIII activity levels that are in or near to the normal range with both median and mean values of 49 percent. BioMarin added that median annualised bleed and factor VIII use rates for the 4e13 vg/kg cohort were zero after week four when their factor VIII activity rose above 5 percent. 

Meanwhile, the drugmaker indicated that all seven patients at the 6e13 vg/kg dose have been followed for at least 78 weeks post-infusion. Results showed that in these patients, median and mean factor VIII levels from week 20 through 78 have been consistently within the normal range. At 78 weeks post-infusion, the median and mean factor VIII levels are 90 percent and 89 percent, respectively. Further, the median annualised bleed and factor VIII use rates for the 6e13 vg/kg cohort were zero after week four. 

BioMarin plans to initiate two Phase III studies of valoctocogene roxaparvovec, with one investigating the 6e13 vg/kg dose and the other evaluating the 4e13 vg/kg dose. The company noted that GENEr8-1, which will test the higher dose, will enrol its first patient this month, while GENEr8-2, which will investigate the lower dose, will recruit its first subject at the start of 2018. The primary endpoint of the trials will be a change from baseline factor VIII activity level, while secondary goals will measure annualised factor VIII replacement therapy use rate and annualised bleed rate.

For further information, see Analyst Notes: Haemophilia A - Major brands leave doctors underwhelmed despite perceived efficacy.


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