By Blake Brittain

WASHINGTON, Feb 20 (Reuters) - Biotech company Regenxbio RGNX.O and the University of Pennsylvania on Friday convinced a U.S. appeals court to revive their patent lawsuit against Sarepta Therapeutics SRPT.O over Sarepta's Duchenne muscular dystrophy (DMD) treatment.

The U.S. Court of Appeals for the Federal Circuit reinstated the case after reversing a Delaware federal judge's ruling that had invalidated the patent at issue, which relates to Regenxbio's competing gene-therapy technology.

Spokespeople and attorneys for the companies and Penn did not immediately respond to requests for comment on the decision.

DMD is a severe degenerative genetic disorder that primarily affects boys. The U.S. Food and Drug Administration approved Sarepta's Elevidys, the first gene therapy for DMD, in 2023, and the drug earned Cambridge, Massachusetts-based Sarepta $898.7 million in revenue in 2025, according to a company report.

Rockville, Maryland-based Regenxbio is developing its own DMD treatment. Its 2020 lawsuit said that Elevidys infringed a gene-therapy patent that Regenxbio licenses from Penn.

Regenxbio and Penn have requested more than $900 million in damages in the case, according to a court transcript.

U.S. District Judge Richard Andrews dismissed the case after determining in 2024 that the patent was invalid because it covers naturally occurring DNA sequences. A three-judge panel reversed Andrews' decision on Friday, finding that the patent covers genetically engineered cells with a molecule that is "markedly different from anything occurring in nature."

The case is Regenxbio Inc v. Sarepta Therapeutics Inc, U.S. Court of Appeals for the Federal Circuit, No. 24-1408.

For Regenxbio: Susan Morrison of Fish & Richardson

For Penn: Julie Goldemberg of Morgan Lewis & Bockius

For Sarepta: Robert Wilson of Quinn Emanuel Urquhart & Sullivan

Read more:

Sarepta defeats Regenxbio, UPenn patent lawsuit over muscular dystrophy treatment

(Reporting by Blake Brittain in Washington)

((blake.brittain@tr.com; +1 (202) 938-5713))