Pfizer has unveiled positive results for its fidanacogene elaparvovec, its investigational gene therapy for haemophilia B in adult men, from Phase 3 BENEGENE-2 study.

The Phase 3 study has met its primary endpoint of non-inferiority and superiority in the annualised bleeding rate (ABR) of total bleeds with fidanacogene elaparvovec, compared to prophylaxis regimen with Factor IX (FIX).

A single dose of fidanacogene elaparvovec resulted in a 71% reduction in ABR.

The key secondary endpoints of the study showed a 78% reduction in treated ABR and a 92% reduction in annualised infusion rate.

Pfizer said that the treatment using fidanacogene elaparvovec was generally well-tolerated, and its safety profile is consistent with Phase 1/2 results.

Fourteen serious adverse events (SAEs) were reported, with no deaths, SAEs related to infusion reactions, thrombotic events, or FIX inhibitors reported.

Pfizer global product development oncology and rare disease chief development officer Chris Boshoff said: “Pfizer has more than 30 years of experience in developing and commercializing therapies for haematological disorders, and a deep understanding of the significant challenges that people living with haemophilia continually face.

“We are proud to advance the latest innovation for people living with haemophilia B and are encouraged by the potential of this investigational gene therapy.

“We are extremely appreciative of those who are participating in the trial and to the investigators contributing to this innovative research as we work to unlock the full potential of gene therapies for people living with haemophilia.”

Fidanacogene elaparvovec is a novel, investigational vector that contains a bio-engineered adeno-associated virus (AAV) capsid and a high-activity human coagulation FIX gene.

The gene therapy is designed to help people living with haemophilia B, by enabling them to produce FIX through a one-time treatment rather than regularly receiving exogenous FIX.

Pfizer licensed the drug from Spark Therapeutics, a Pennsylvania-based gene therapy treatments developer, through an agreement dated December 2014.

Under the terms of the agreement, Pfizer is responsible for conducting late-stage studies, potential regulatory activities, and global commercialisation.

The drug has been granted breakthrough, regenerative medicines advance therapy (RMAT), and orphan drug designations from the US Food and Drug Administration

Also, it has received PRIority MEdicines (PRIME) and orphan drug designation from the European Medicines Agency.

Pfizer is currently developing gene therapy in three Phase 3 programmes, among haemophilia B, haemophilia A, and Duchenne muscular dystrophy populations.