Pfizer and Sangamo Therapeutics will soon resume a Phase 3 trial of their gene therapy for the blood disorder hemophilia A, nearly a year after safety concerns forced its suspension.
Specifically, the companies said Thursday evening they plan to resume recruiting patients for the study this month and restart dosing with the treatment in October.
The study was originally paused last fall due to safety concerns over blood clotting. The gene therapy, dubbed giroctocogene fitelparvovec, is meant to treat people with severe hemophilia A, who either lack or have low levels of a needed blood clotting protein.
In some patients, treatment led to higher-than-normal levels of that blood clotting protein and a number were put on oral blood thinners as a result. Later, Pfizer disclosed that one patient experienced deep vein thrombosis in the leg alongside elevated clotting protein levels.
The Food and Drug Administration lifted a clinical hold it had imposed in May, allowing Pfizer and Sangamo to proceed with testing after they adjusted their study protocol.
The two companies originally aimed to resume dosing before the end of September, but now anticipate a slightly later restart. Trial data, previously pegged for 2023, is now expected in early 2024, Pfizer said Thursday.
The delays in testing could put Pfizer and Sangamo’s therapy behind a competing treatment from BioMarin Pharmaceutical. While that therapy was rejected by the FDA in 2020, the company has gathered more data and expects to resubmit an application to the FDA this month. The treatment, called Roctavian, won authorization in Europe in August.
Roche, meanwhile, is further behind in developing a hemophilia gene therapy that it secured in acquiring Spark Therapeutics.