FDA lifts hold on Pfizer hemophilia trial

Pfizer can resume its hemophilia trials after a clinical hold from the U.S. FDA was lifted, but its ‘voluntary pause’ will continue. 

A recent announcement from Pfizer revealed the agency had dropped its hold on the hemophilia A trial in March. That study, a phase 3 trial called Affine, was examining the use of a gene therapy called giroctocogene fitelparvovec in patients with hemophilia A, which prevents blood from clotting properly. 

But, despite agency approval, Pfizer said it will hold off on dosing new patients until at least July as it works on new study protocols with the FDA. This comes amidst news that one of the patients dosed in the original Affine study experienced deep vein thrombosis in the leg and elevated levels of blood clotting proteins, according to Pfizer.

That patient is doing well, but should’ve been excluded from the study, said Pfizer. The patient had a history of thrombosis events prior to the study, which is a risk factor for future clotting events.

The trial was originally stopped due to concerns about clotting factors in patients, which rose to 150% of normal after an infusion of the gene therapy.

Once Pfizer gets the Affine trial back up and running, the pharma giant is looking to enroll 63 participants.

The company will also move forward with its late-stage trials for Duchenne muscular dystrophy after the FDA lifted a clinical hold. That hold came in December, after the death of a patient in its phase 1b study. The patient’s death in the early study was ultimately linked to a more advanced disease with an underlying cardiac dysfunction, said Pfizer.