FDA Clears Resumption of Pfizer's Phase 3 CIFFREO Trial for DMD Gene Therapy fordadistrogene movaparvovec

Today, Pfizer announced that the U.S. FDA has notified the company that its Phase 3 clinical trial for the gene therapy fordadistrogene movaparvovec, used to treat Duchenne muscular dystrophy (DMD), is allowed to continue. This global Phase 3 clinical trial, named CIFFREO, was paused in December last year due to a fatal adverse event in a patient during the Phase 1b clinical study. Pfizer revised the clinical trial protocol, adding a 7-day hospital observation period to enable healthcare professionals to more closely monitor and manage patients receiving the gene therapy. The company also addressed the FDA’s questions regarding potency assays. Currently, regulatory agencies in multiple countries and regions worldwide have approved the resumption of this Phase 3 clinical study. Pfizer anticipates that almost all CIFFREO clinical trial sites globally will reopen by the end of June.

DMD is a rare genetic disease caused by mutations in the gene encoding dystrophin on the X chromosome. The absence or defect of dystrophin leads to chronic damage and inflammation during muscle contraction, affecting muscle regeneration. Eventually, muscles are replaced by scar tissue or fat. Patients urgently need treatment options that can alter the disease progression.

Fordadistrogene movaparvovec, developed by Pfizer, is an investigational intravenous gene therapy. It packages a "mini" dystrophin transgene controlled by a human muscle-specific promoter into an adeno-associated virus 9 (AAV9) vector. The AAV9 viral vector has the ability to deliver the transgene specifically to muscle tissues. This investigational therapy has been granted Orphan Drug Designation, Rare Pediatric Disease Designation, and Fast Track Designation by the FDA.

Previously released Phase 1b clinical trial results showed that after 12 months of treatment, patients demonstrated sustained and statistically significant improvements, including persistent levels of micro-dystrophin expression (measured using liquid chromatography-mass spectrometry and immunofluorescence staining), as well as improved scores on the NorthStar Ambulatory Assessment (NSAA), a validated measure of muscle function.

"Duchenne muscular dystrophy is a serious disease with very limited treatment options, and we believe that gene therapy has the potential to significantly alter the course of the disease," said Dr. Brenda Cooperstone, Chief Development Officer for Rare Disease Global Product Development at Pfizer. "We are pleased to continue advancing the CIFFREO study and are moving as quickly as possible to restart clinical trial sites after receiving approval from local regulatory authorities."

References:

[1] Pfizer to Open First U.S. Sites in Phase 3 Trial of Investigational Gene Therapy for Ambulatory Patients with Duchenne Muscular Dystrophy. Retrieved April 28, 2022, from https://www.pfizer.com/news/press-release/press-release-detail/pfizer-open-first-us-sites-phase-3-trial-investigational

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