With the clearance to restart the hemophilia A trial, Pfizer has now successfully ticked off two safety boxes for its gene therapy research pipeline. Last week, the company announced the FDA OK’d resumption of a trial of its experimental treatment for Duchenne muscular dystrophy, which had been stopped because of side effects and the death of a patient.
In the case of the hemophilia trial, the worries over thromboses were triggered by findings that patients’ levels of clotting factor rose to 150% of normal after an infusion of the gene therapy. The protein is largely missing in hemophilia A patients, and the gene therapy stimulates its production by replacing a faulty gene responsible for making it.
