News & Insights

No (Judicial) Exceptions Here: Federal Circuit Finds Genetically Engineered Cells Patent-Eligible in REGENXBIO v. Sarepta

February 25, 2026

By: Deirdre E. Sanders and Kelly Brewer, Ph.D.

• Federal Circuit finds genetically engineered host cells patent-eligible, reversing lower court’s § 101 ruling
• Claims to genetically engineered constructs with “markedly different characteristics” from natural products can clear patent-eligibility hurdles, even where utility is only implicit

Case Highlights
In REGENXBIO Inc. v. Sarepta Therapeutics, Inc., the U.S. Court of Appeals for the Federal Circuit (CAFC) issued a precedential decision on February 20, 2026, reversing a district court’s earlier summary judgment ruling that claims to a genetically engineered host cell were directed to a patent-ineligible natural phenomenon.

REGENXBIO Inc. and The Trustees of the University of Pennsylvania (collectively, “REGENXBIO”) had filed a patent infringement suit in the United States District Court for the District of Delaware against Sarepta Therapeutics, Inc. and Sarepta Therapeutics Three, LLC (“Sarepta”). Both parties moved for summary judgment of patent eligibility under 35 U.S.C. § 101.

The patent at issue, U.S. Patent No. 10,526,617, claims cultured host cells containing recombinant adeno-associated virus (AAV) DNA used in producing gene therapy products. Sarepta had argued that the claims were nothing more than products of nature.  The district court agreed, likening the disputed claims to unpatentable claims relating to bacteria mixtures in Funk Brothers Seed Co. v. Kalo Inoculant Co. (which possessed “no enlargement of the range of their utility”) and to isolated BRCA1/2-coding DNA in Association for Molecular Pathology v. Myriad Genetics, Inc. (The Myriad case also involved claims relating to complementary DNA (cDNA) which were patent-eligible).

The CAFC disagreed, determining that this analysis was flawed in that it did not consider whether the claimed composition as a whole was “naturally occurring.”  Instead, the CAFC unanimously held that the claimed host cells satisfy the “markedly different characteristics” test from Diamond v. Chakrabarty, 447 U.S. 303 (1980), and, thus, are distinct from products of nature and are eligible subject matter under 35 U.S.C. § 101. The CAFC noted that the claimed cells contain recombinant nucleic acid, and that the nucleic acid comprises a heterologous sequence.  Thus, the claims at issue were “not nature’s handiwork” and were more analogous to the patent-eligible claims relating to human-made plasmids in Chakrabarty and cDNA in Myriad, than to the patent-ineligible claims of Funk Bros and Myriad.  Further, the CAFC noted that the court may consider whether the claimed invention has the potential for utility, even where that utility is not recited in the claim.

The CAFC reversed the district court and remanded the case for further proceedings, effectively reviving REGENXBIO’s patent infringement suit. This precedential ruling affirms robust patent protection for engineered biotechnological inventions and has meaningful implications for patent strategy across the life sciences.

Strategic Implications

This ruling has major implications for patent holders, applicants for patents, and innovators in the life sciences:

• Reinforces Established Precedent: The decision affirms that engineered biological compositions that do not occur in nature — even if they incorporate natural elements — remain patent eligible when they exhibit meaningful human-engineered differences.
• Patent drafting strategies: Strategic claim drafting should emphasize human manipulation and marked differences from natural products, particular for claims relating to biologics, vectors, and host cell technologies. Patent applications should provide indications of the potential for significant utilities for the claimed invention.
• Strategic Claim Considerations: The decision provides insight into elements that may weigh in favor of patent eligibility, such as:
• a non-natural combination of natural components, e.g., a recombinant molecule with specific heterologous components;
• a human-made molecule produced using a natural template, e.g., cDNA generated using mRNA; and
• structural elements proffering the potential for significant utility, even if the utility itself is not claimed; e.g., a non-natural property of a genetically engineered organism containing recombinant/heterologous DNA.
• Litigation Dynamics: For patent owners, this case opens the door for renewed infringement actions previously thought more vulnerable to eligibility attacks. For challengers, it raises the bar for successfully arguing natural phenomenon ineligibility.

Expert Support

Emerging biotech and life-science innovators navigating intellectual property complexity will benefit from guidance grounded in both legal insight and technical understanding.

Contact Deirdre Sanders, Kelly Brewer, Ph.D., or your regular practitioner at Hamilton Brook Smith Reynolds to learn more.