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Pfizer received Fast Track designation from the U.S. Food and Drug Administration (FDA) and has begun dosing in the Phase 3 trial for its investigational gene therapy for Duchenne muscular dystrophy (DMD)

In October, the FDA granted Fast Track designation to Pfizer’s investigational gene therapy candidate, PF-06939926, which is being developed to treat boys living with DMD.


It is estimated that there are about 140,000 boys affected with DMD worldwide and approximately 30,000 in the U.S. and Europe.2

Fast Track is an FDA process designed to facilitate the development and expedite the review of new drugs to treat or prevent serious conditions that have the potential to address an unmet medical need. This designation was granted based on data from the Phase 1b study that indicated the intravenous administration of PF-06939926 was well tolerated during the infusion period and dystrophin expression levels were sustained over a 12-month period.

We believe our gene therapy candidate, if successful in Phase 3 and approved, has the potential to significantly improve the trajectory of DMD disease progression, and we are working with worldwide regulatory authorities to initiate this program as quickly as possible in other countries.​​​​​​​"

Brenda Cooperstone, M.D.

Chief Development Officer, Rare Disease, Pfizer Global Product Development

“The FDA’s decision to grant our investigational gene therapy PF-06939926 Fast Track designation underscores the urgency to address a significant unmet treatment need for DMD,” said Brenda Cooperstone, M.D., Chief Development Officer, Rare Disease, Pfizer Global Product Development.

Pfizer also initiated a Phase 3 study of PF-06939926 and dosed the first patient in December 2020.

DMD is a devastating and life-threatening X-linked disease caused by mutations in the gene encoding dystrophin needed for proper muscle membrane stability and function. Patients present with muscle degeneration that progressively worsens with age to the extent that they require wheelchair assistance when they are in their early teens and often succumb to their disease by the time they are in their late 20s.1 It is estimated that there are about 140,000 boys affected with DMD worldwide and approximately 30,000 in the U.S. and Europe, so treatment options are desperately needed.2

​​​​​​​“DMD is a devastating condition, and patients and their families, are waiting desperately for treatment options. We are working to advance our planned Phase 3 program as quickly as possible,” Cooperstone said.

People living with DMD experience muscle degeneration that progressively worsens with age, typically leading to the need for wheelchair assistance when they are in their early teens.


1Emery AEH. The muscular dystrophies. Lancet. 2002;359:687-695. 

2Internal data on file. 

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