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# FDA Lifts Hold on Pfizer Duchenne Gene Therapy
- URL: https://www.fdaweb.com/fda-lifts-hold-on-pfizer-duchenne-gene-therapy/
- Published: 2022-04-28T12:00:00.000Z
- Updated: 2026-09-14T17:42:28.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5151703

FDA has lifted a clinical hold on Pfizer’s mini-dystrophin gene therapy, fordadistrogene movaparvovec, in ambulatory patients with Duchenne muscular dystrophy (DMD). The company is now planning to resume a Phase 3 study evaluating the therapy.

The global study, CIFFREO, had been ongoing in 11 countries and was paused in 12/2021 to “implement a protocol amendment following a fatal serious adverse event that occurred in a Phase 1b study in the non-ambulatory cohort,” Pfizer says. “To date, regulatory authorities in the United Kingdom, Canada, Taiwan, Spain and Belgium have approved the re-start of the Phase 3 study and additional global reviews are ongoing.”

Further explaining the adverse event, Pfizer says that like many non-ambulatory DMD patients, the “participant had more advanced disease with underlying cardiac dysfunction. Pfizer immediately paused screening, randomization and dosing in all studies of fordadistrogene movaparvovec as the independent external Data Monitoring Committee (eDMC) reviewed the data, and the U.S. FDA subsequently placed the IND on clinical hold.”

The clinical hold removal follows reviews of data and protocol amendments. “The protocol amendments include a seven-day hospitalization period to enable close monitoring and management of patients following administration of gene therapy,” Pfizer says. “In addition, Pfizer has addressed the U.S. FDA’s questions related to the potency assay to enable the trial to proceed in the United States.”

Fordadistrogene movaparvovec is described as a recombinant adeno-associated virus serotype 9 (AAV9) capsid carrying a shortened version of the human dystrophin gene (mini-dystrophin) under the control of a human muscle-specific promotor, according to the company. It chose the AAV9 capsid as the delivery mechanism because of its potential to target muscle tissue.