Federal Circuit Rules Engineered Cells Are Patent Eligible

REGENXBIO's gene therapy host cells deemed a 'non-naturally occurring manufacture'

Mar. 28, 2026 at 6:08am

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In a significant ruling for the biotech industry, the U.S. Federal Circuit Court of Appeals has determined that genetically engineered host cells used to produce gene therapy products are patent-eligible subject matter. The court found that REGENXBIO's engineered cells, which contain adeno-associated virus (AAV) capsid sequences, constitute a 'non-naturally occurring manufacture' and thus meet the criteria for patentability established in the landmark Diamond v. Chakrabarty Supreme Court decision.

Why it matters

This decision provides important clarity on the patent eligibility of biotech inventions in the U.S., closing a gap with the more applicant-friendly framework used at the European Patent Office. The ruling affirms that terms like 'recombinant,' 'heterologous,' and 'genetically engineered' can help navigate U.S. patent subject matter eligibility requirements, a key consideration for biotech companies seeking to protect their innovations.

The details

The Federal Circuit overturned a lower court decision that had invalidated REGENXBIO's patent claims on the engineered host cells. The appeals court rejected the district court's reliance on the outdated 'Funk Brothers' precedent, clarifying that the proper framework is the 'Chakrabarty standard' established by the Supreme Court. Under this approach, the court determined that REGENXBIO's cells, which contain a recombinant nucleic acid molecule with both AAV and non-AAV sequences, have 'markedly different characteristics' and 'significant utility' compared to naturally occurring cells, and therefore constitute patent-eligible subject matter.

  • The Federal Circuit issued its ruling on March 28, 2026.

The players

REGENXBIO, Inc.

A biotechnology company focused on the development of gene therapy products.

Sarepta Therapeutics, Inc.

A pharmaceutical company that was sued by REGENXBIO for infringing its patent on engineered host cells.

U.S. Federal Circuit Court of Appeals

The appellate court that overturned the lower court's decision and ruled in favor of REGENXBIO's patent eligibility.

U.S. District Court for the District of Delaware

The lower court that had initially invalidated REGENXBIO's patent claims.

Diamond v. Chakrabarty

The landmark 1980 Supreme Court decision that established the framework for assessing the patent eligibility of biotechnology inventions.

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What they’re saying

“This decision provides important clarity on the patent eligibility of biotech inventions in the U.S., closing a gap with the more applicant-friendly framework used at the European Patent Office.”

— Lucy Barnes, Patent Attorney, J A Kemp LLP

What’s next

The ruling in REGENXBIO v. Sarepta is expected to have a significant impact on how the U.S. Patent and Trademark Office and courts evaluate the patent eligibility of biotechnology inventions going forward.

The takeaway

This decision marks an important win for the biotech industry, affirming that genetically engineered cells and other non-naturally occurring biotechnology products can be protected by patents in the United States. The ruling provides a clear framework for navigating the complex issue of patent eligibility and should encourage further innovation in the field of gene therapy and other cutting-edge biotechnologies.