Pfizer Announces First Patient Dosed in Pivotal Phase 3 Trial of Investigational Gene Therapy PF-06939926 for Duchenne Muscular Dystrophy

Pfizer Announces First Patient Dosed in Phase 3 Trial of Investigational Gene Therapy PF-06939926 for Duchenne Muscular Dystrophy (DMD)Pfizer Inc. announced today that the first patient has been dosed with its investigational gene therapy, PF-06939926, for the treatment of Duchenne Muscular Dystrophy (DMD), marking the initiation of dosing in its Phase 3 clinical trial. The Phase 3 trial, named CIFFREO, is expected to enroll 99 ambulatory male patients aged 4 to 7 years across 55 clinical trial sites in 15 countries. The press release highlighted that this is the first Phase 3 clinical trial of a gene therapy for patients with DMD, representing a significant milestone for this patient population.

Duchenne Muscular Dystrophy (DMD) is a rare genetic disorder caused by mutations in the gene on the X chromosome that encodes dystrophin. The absence or defect of dystrophin leads to chronic muscle damage during contraction, triggers inflammatory responses, and impairs muscle regeneration. Ultimately, muscle tissue is replaced by scar tissue or fat. Symptoms of muscle weakness become apparent at age 2–3 years; as muscle tissue and function continue to deteriorate, patients are typically confined to a wheelchair by age 12, require assisted ventilation by age 20, and face premature death in their 30s or 40s due to respiratory or cardiac failure.

PF-06939926, developed by Pfizer, is an investigational intravenous gene therapy. It consists of a “mini-dystrophin” transgene controlled by a human muscle-specific promoter, packaged in an adeno-associated virus serotype 9 (AAV9) vector. The AAV9 viral vector has the ability to target and deliver the transgene to muscle tissue. This investigational therapy has been granted orphan drug designation, rare pediatric disease designation, and fast track designation by the FDA.

Results from the Phase 1b study published last year showed that nine DMD patients aged 6 to 12 years received treatment with PF-06939926. After 12 months of treatment, patients demonstrated durable and statistically significant improvements, including sustained levels of micro-dystrophin expression (assessed by liquid chromatography-mass spectrometry and immunofluorescence staining) and improved scores on the North Star Ambulatory Assessment (NSAA), a validated measure of muscle function.

“Our pivotal clinical trial is the first Phase 3 gene therapy program for Duchenne muscular dystrophy (DMD) to enroll patients, marking a significant milestone for the patient community. Currently, there are no approved disease-modifying treatments available for all genetic types of DMD,” said Dr. Brenda Cooperstone, Chief Development Officer of Pfizer Rare Disease. “We believe that if this investigational gene therapy succeeds in Phase 3 clinical trials and gains approval, it has the potential to significantly alter the trajectory of DMD progression. We are collaborating with regulatory authorities worldwide to initiate this program in other countries as soon as possible.”

Note: This article is intended to introduce medical and health research and does not constitute a recommendation for treatment plans. For guidance on treatment options, please consult a licensed healthcare provider at a reputable hospital.

References:

[1] Pfizer Doses First Participant in Phase 3 Study for Duchenne Muscular Dystrophy Investigational Gene Therapy. Retrieved January 7, 2021, from https://www.businesswire.com/news/home/20210107005031/en

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