For a third time, Sarepta Therapeutics has convinced a top Food and Drug Administration official to overrule the prevailing view of their staff and approve a drug for Duchenne muscular dystrophy. On Thursday evening, the FDA announced it expanded the approval of Elevidys, Sarepta’s Duchenne gene therapy, to cover nearly all patients, regardless of age or wheelchair status, despite the fact that the drug failed a large, Phase 3 trial last year. That decision, documents concurrently released by the agency show, was made almost exclusively by Peter Marks, the agency’s director of the Center for Biologics Evaluation and Research. He...