By Colin Kellaher

Pfizer Inc. on Thursday said it dosed the first patient in a Phase 3 study of its investigational gene-therapy candidate PF-06939926 in boys with Duchenne muscular dystrophy, or DMD.

The New York drugmaker on Thursday said the pivotal trial is the first Phase 3 gene-therapy program to begin enrolling eligible patients with DMD, a fatal neuromuscular genetic disease that occurs in roughly one in every 3,500 to 5,000 males.

There are currently no approved disease-modifying treatment options available for all genetic forms of DMD, which is caused by a change or mutation in the gene that encodes instructions for dystrophin, a protein found in muscle cells.

Pfizer said it expects the study to enroll 99 patients across 55 sites in 15 countries.

The U.S. Food and Drug Administration in October granted fast-track designation to PF-06939926, which had previously received orphan-drug and rare-pediatric-disease designations from the agency.

Write to Colin Kellaher at colin.kellaher@wsj.com

(END) Dow Jones Newswires

01-07-21 0810ET