FDA Approves Pfizer’s Phase 3 Clinical Trial of DMD Gene Therapy

Today, Pfizer announced that the U.S. Food and Drug Administration (FDA) has notified the company that the Phase 3 clinical trial of its gene therapy fordadistrogene movaparvovec for the treatment of Duchenne muscular dystrophy (DMD) will continue. The global Phase 3 clinical trial, called CIFFREO, was suspended in December last year after a fatal adverse event occurred in a patient in the Phase 1b clinical study. Pfizer made changes to its clinical trial process, adding a seven-day observation period in the hospital, allowing healthcare workers to more closely monitor and manage patients receiving gene therapy. The company also answered FDA questions about potency testing. At present, regulatory agencies in many countries and regions around the world have allowed this phase 3 clinical study to be restarted. Pfizer expects nearly all CIFFREO clinical trial sites around the world to reopen by the end of June this year.

DMD is a rare genetic disorder caused by mutations in the gene encoding dystrophin on the X chromosome. The absence or deficiency of dystrophin results in chronic muscle damage during contraction, inflammation flares, and impaired muscle regeneration. Eventually, the muscle is replaced by scar tissue or fat. Patients urgently need treatment options that alter the course of the disease.

Fordadistrogene movaparvovec, developed by Pfizer, is an investigational intravenous gene therapy. It packs a "mini" dystrophin transgene controlled by a human muscle-specific promoter in an adeno-associated virus 9 (AAV9) vector. AAV9 viral vectors have the ability to target transgenes to muscle tissue. The investigational therapy has been granted orphan drug designation, rare pediatric disease designation and Fast Track designation by the FDA.

Previously published Phase 1b clinical trial results showed that after 12 months of treatment, patients showed durable and statistically significant improvements, including sustained levels of micro-dystrophin expression (using liquid chromatography mass spectrometry and immunofluorescence staining). method), and improvement in scores on the NorthStar Outpatient Assessment Scale (NSAA), a validated measure of muscle function.

"Duchenne muscular dystrophy is a serious disease with very limited treatment options, and we believe gene therapy has the potential to significantly alter the course of the disease," said Dr. Brenda Cooperstone, chief development officer, global product development for rare diseases at Pfizer. "We are excited to continue advancing CIFFREO. Research, at the fastest speed, after obtaining permission from local regulators, is restarting clinical trial sites."