So far, so good for Pfizer (NYSE: PFE) and Sangamo Therapeutics' (NASDAQ: SGMO) gene therapy candidate, giroctocogene fitelparvovec, which the healthcare companies are developing for patients with hemophilia A.
None of the five patients in the phase 1/2 clinical trial treated at the highest dose has had a bleeding event or required infusions of Factor VIII, the protein that's missing in patients with hemophilia A. The patients, the longest of whom has been followed for over 14 months, had an average Factor VIII activity level that was 64.2% of normal.
The data looks comparable to that generated by BioMarin Pharmaceuticals' (NASDAQ: BMRN) hemophilia A gene therapy, valoctocogene roxaparvovec, which produced an average Factor VIII activity level 60% of normal one year after treatment at the highest dose. Patients' levels dropped off substantially as time went on, however -- at the four-year mark, the Factor VIII activity level was only 16.4% of normal.