February 23, 2026-REGENXBIO has won a key appellate ruling in its long-running AAV patent dispute with Sarepta Therapeutics over core AAV vector technology used in Duchenne muscular dystrophy gene therapy.
An appellate court overturned a January 2024 lower court decision that had invalidated REGENXBIO’s AAV patent on the grounds that its elements were naturally occurring. Writing for the court, Judge Kara Stoll stated that the claims were not merely directed to repackaging products of nature, emphasizing that the patented AAV composition creates a cell containing a molecule that could not form in nature on its own. The court found that the earlier ruling took too narrow a view by focusing on whether individual AAV components were naturally occurring, rather than assessing whether the claimed AAV composition as a whole was non-natural.
The patent—owned by University of Pennsylvania and licensed to REGENXBIO—covers foundational AAV vector platform technology. REGENXBIO and Penn filed suit in 2020, alleging that Sarepta used the protected AAV platform in the gene therapy that became Elevidys, which was approved in June 2023 for Duchenne muscular dystrophy.
The appellate decision sends the case back to the lower court for reconsideration and reinforces the importance of intellectual property protection in the AAV gene therapy field, where vector design, capsid engineering, and AAV composition claims underpin many approved and investigational therapies.
The ruling comes amid broader challenges for both companies. REGENXBIO recently faced regulatory setbacks for its AAV gene therapy candidates targeting Hunter syndrome and Hurler syndrome, including an FDA rejection and a clinical hold. Sarepta, meanwhile, has reported safety concerns associated with Elevidys, including patient deaths, leading to a strategic shift toward siRNA programs and updated labeling restrictions.
As AAV-based gene therapy continues to expand across rare disease indications, this decision may have significant implications for how courts evaluate AAV platform patents—particularly whether engineered AAV compositions are viewed as naturally occurring or as patent-eligible biotechnological innovations.
