Sarepta Therapeutics witnessed a significant surge in its stock prices, climbing up to 40% following the FDA's expanded approval for its gene therapy, Elevidys (delandistrogene moxeparvovec-rokl), now covering Duchenne muscular dystrophy (DMD) patients aged four and above who have a confirmed mutation in the DMD gene. The expanded approval encompasses both ambulatory and non-ambulatory patients, with traditional approval granted for those who can walk and accelerated approval for those who cannot, expanding the potential market for Elevidys substantially.

Elevidys, which initially received accelerated approval for ambulatory patients aged 4 to 5, now covers a broader patient demographic, including non-ambulatory children, contingent upon the outcomes of the Envision study, expected to conclude in 2027. The FDA's decision, seen as a "grand slam" by analysts, represents a significant milestone, signaling the potential for over a tenfold increase in the therapy's market. This optimism is buoyed by Elevidys' reported sales of $200 million in just three quarters under a narrower label, with projections of reaching about $1 billion in sales by 2024.

The FDA's endorsement, despite mixed test results and initial resistance from some of its staffers, underscores a flexible approach towards gene therapies for debilitating diseases like DMD. Dr. Peter Marks, who leads the Center for Biologics Evaluation and Research, ultimately approved Elevidys based on the potential long-term benefits outlined by biomarker increases, even in the face of concerns from his colleagues.

Looking ahead, Sarepta faces the challenges of meeting manufacturing demands and ensuring insurance reimbursement for Elevidys. The company has already partnered with Catalent and Thermo Fisher Scientific to tackle production, anticipating significant demand for the therapy across a now broader eligible population. Insurance coverage and potential manufacturing constraints are critical factors that will influence the therapy's uptake and accessibility.

The recent developments have not only caused a notable rise in Sarepta's stock but have also positively impacted other companies in the gene therapy space, including Regenxbio and Solid Biosciences, both of which are developing treatments for DMD. The FDA's willingness to broaden Elevidys’ label may bode well for future gene therapy approvals, potentially transforming the treatment landscape for diseases like DMD, characterized by severe muscle degeneration and early mortality.

This expanded approval could revolutionize the management of Duchenne muscular dystrophy, offering new hope to patients and their families and setting a precedent for regulatory flexibility in the face of innovative but expensive gene therapies, with Elevidys costing around $3.2 million per patient. As the gene therapy market continues to evolve, Sarepta Therapeutics' latest victory with Elevidys may pave the way for more accessible and effective treatments for rare genetic conditions.