STAT+: Perplexing results from Duchenne muscular dystrophy trial raise questions about gene therapies

Confounding data from a Pfizer clinical trial has rattled the field of gene therapy for Duchenne muscular dystrophy, raising more questions about the regulatory standard used to approve a treatment from Sarepta Therapeutics, and complicating plans for other companies hoping to develop next-generation products. 

Scientifically, Pfizer’s gene therapy did what it was supposed to do. Boys who received it as part of a Phase 3 clinical trial produced significant amounts of microdystrophin, a lab-built miniature version of the gene mutated in Duchenne. In principle, that should have helped slow a disease that can rob patients of the ability to walk by age 12 and cut lifespan to under 30. Yet, the participants didn’t benefit at all. The outcome of multiple muscle function tests — the study’s key efficacy goals — showed no improvement compared to a placebo. 

The discordant trial results, presented on Oct. 12 at the World Muscle Society meeting, left many Duchenne experts perplexed.

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