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Federal Circuit Finds Claims as a Whole Directed to Patent Eligible Non-Naturally Occurring Composition
03/03/2026On February 20, 2026, the Court of Appeals for the Federal Circuit (“CAFC”) issued a precedential opinion reversing and remanding a decision from the United States District Court for the District of Delaware finding the asserted claims of appellant’s patent invalid as directed to a patent-ineligible natural phenomenon under 35 U.S.C. § 101. Regenxbio Inc. v. Sarepta Therapeutics, Inc., __ F.3d __ (Fed. Cir. February 20, 2026). In reaching its decision, the CAFC concluded, inter alia, that the asserted claims were directed to patent eligible unique human-made compositions, even if comprising naturally occurring components.
Appellant patentee accused appellee defendant of infringing certain claims of U.S. Patent No. 10,526,617 (“the ’617 patent”). The asserted claims of this patent are directed to a host cell containing a recombinant nucleic acid molecule comprising two distinct amino acid sequences obtained from different organisms that are spliced together. Both parties moved for summary judgment on the question of patent eligibility under § 101.
Starting with the “markedly different characteristics” test from Diamond v. Chakrabarty, 447 U.S. 303 (1980), the district court determined that none of the individual naturally occurring amino acid sequences in the claims had been changed and that combining natural products and putting them in a host cell does not make the invention patentable under § 101. Instead, the district court determined that the claims were similar to the ineligible claims in Funk Brothers Seed Co. v. Kalo Inoculant Co., 333 U.S. 127 (1948), because taking amino acid sequences from two different organisms and putting them together is no different than taking two strains of bacteria and mixing them together. The district court further considered and disregarded that the claimed human-made genetically engineered host cell possessed utility for gene therapy because nothing in the claims is directed to use for a particular purpose. The district court, last, concluded that the claims were invalid because they failed to recite an inventive concept under step two of the Alice/Mayo framework. The patentee appealed.
The CAFC began its review of the district court’s decision by providing an overview of relevant precedent on § 101, starting with the Supreme Court’s decision in Chakrabarty. As explained by the CAFC, Chakrabarty upheld a claim to a new bacterium, comprised of four different naturally occurring plasmids—each from a different source—wherein the bacterium had markedly different characteristics from any bacterium found in nature and had the potential for significant utility. In Chakrabarty, the Supreme Court also distinguished Funk Brothers on the basis that each bacterium within the mixture claimed in Funk Brothers behaved as it always had in nature and was not improved by the mixture. The CAFC next explained that, in Association for Molecular Pathology v. Myriad Genetics, Inc., 569 U.S. 576 (2013), the Supreme Court held patent eligible a claim to a non-naturally occurring nucleic acid derived from nature but having certain portions of its amino acid sequence removed. Last, the CAFC reviewed its own previous decision in ChromaDex, Inc. v. Elysium Health, Inc., 59 F.4th 1280 (Fed. Cir. 2023). In ChromaDex, the CAFC found ineligible claims reciting a composition including an isolated vitamin—NR—found in milk in combination with other elements also found in milk wherein the composition increases a certain biosynthesis reaction when ingested. The CAFC explained that these claimed compositions do not have characteristics markedly different from milk, do not require any minimum quantity of the isolated NR vitamin, and do not attribute the claimed increase in biosynthesis, which also occurs when natural milk is ingested, to the isolated NR.
Turning to the asserted claims of the ’617 patent, the CAFC stated that Chakrabaty was controlling and required an analysis of whether the claimed host cells have “markedly different characteristics” and have “the potential for significant utility” from those that are naturally occurring. In answering in the affirmative, the CAFC determined that the claims of the ’617 patent are more analogous to the eligible claims in Chakrabarty and Myriad than the ineligible claims in Funk Brothers and ChromaDex.
The CAFC first noted that no party contested that the claimed host cells of the ’617 patent include a human-made recombinant nucleic acid molecule—created through gene splicing—that does not and cannot exist in nature. Next, the CAFC observed that, contrary to the district court’s holding, the claims of the ’617 patent are distinguishable from those in Funk Brothers, because, unlike in Funk Brothers, the ’617 patent claims are not merely directed to repackaging products of nature, but rather to an entirely new host cell. The CAFC faulted the district court’s contrary conclusion as improperly focusing on whether the individual components of the claim were markedly different from what is naturally occurring and as failing to consider whether the claimed composition as a whole was “not naturally occurring.”
The CAFC then noted that it may consider whether the claimed composition has the potential for significant utility under Chakrabarty even if that utility is only implicit—as was indisputably the case with respect to the claims at issue. The CAFC also distinguished its decision of ineligibility in ChromaDex on the basis that the compositions claimed in that case included a functional limitation—increasing biosynthesis by some amount—and that function existed in naturally occurring products.
Accordingly, the CAFC held that the asserted claims were not directed to patent ineligible naturally occurring subject matter, reversed the district court’s summary judgment of ineligibility, and remanded for further proceedings.
