Key Takeaway: Genetically engineered cultured host cells containing recombinant nucleic acids useful for gene therapy are patent-eligible for being markedly different from anything occurring in nature.
In REGENXBIO Inc. v. Sarepta Therapeutics, Inc., 2026 WL 479224 (Fed. Cir. Feb. 20, 2026), the Federal Circuit reversed the district court’s ruling on summary judgement which held that the claims relating to gene therapy are patent ineligible. The claims at issue recited a cultured host cell containing a recombinant nucleic acid molecule that comprise sequences encoding a novel Adeno-Associated Virus (“AAV”) capsid and a heterologous non-AAV sequence.
The district court held the asserted claims were directed towards patent-ineligible material. The district court interpreted the claims as combing naturally occurring components, neither of which had been changed, and putting them in a host cell. The district court determined that the claims are similar to the ineligible claims in Funk Brothers[1], where two strains of bacteria were mixed together, and concluded that simply combining two sequences and putting them in a host cell did not make the invention patentable subject matter under 35 U.S.C. § 101.
On appeal, the Federal Circuit followed Chakrabarty[2] and concluded that the claimed cultured host cells have markedly different characteristics and have the potential for significant utility from what is naturally occurring. The host cells include a recombinant nucleic acid molecule that does not and cannot exist in nature. To make the recombinant nucleic acid molecule, the lab technician must chemically splice together nucleic acid sequences from two different species and then insert the resulting molecule into the host cell. The resulting molecule is therefore a product of human ingenuity.
The Federal Circuit further distinguished the claimed composition from the patent-ineligible mixed cultures in Funk Brothers. In Funk Brothers, the Supreme Court held that while the patented mixed cultures may be an important commercial advancement, discovering that strains of already existing species of bacteria could be mixed without harmful effect to the properties of the bacteria was merely a discovery of the handiwork of nature, and therefore not patent eligible. Combining the strains did not change the way the species of bacteria acted. In contrast, the Federal Circuit held that REGENXBIO’s claimed cultured host cell is not a repackaging of products of nature like the mixed cultures in Funk Brothers, as the molecule inserted into the host cell does not occur naturally.
In addition to finding the claimed composition has markedly different characteristics from what is naturally occurring, while not necessary for its holding, the Federal Circuit also determined that the claimed compositions have the potential for significant utility, as they are beneficial for gene delivery to selected host cells and to gene therapy patients, unlike the naturally occurring counterparts. In making this determination, the Federal Circuit emphasized that the significant utility does not need to be explicitly included in the claims themselves but instead can be implicit.
The decision of the Federal Circuit should have a positive impact on the development of gene therapy moving forward. Creating effective gene therapies, which involve using a modified virus vector to deliver a new therapeutic gene to replace defective or missing genes that cause various genetic disorders, can be a costly venture for companies. Developing a gene therapy can cost billions of dollars, or more than five times the average cost of developing a more traditional drug.[3] In this decision, the Federal Circuit affirmed the patent-eligibility of gene therapy inventions that involve human made materials that are not naturally occurring and which have markedly different characteristics from what occurs in nature.
Editor: Brenden S. Gingrich, Ph.D.
[1] Funk Brothers Seed Co. v. Kalo Inoculant Co., 333 U.S. 127 (1948)
[2] Diamond v. Chakrabarty, 447 U.S. 303 (1980).
[3] Irvine, Alison “Paying for CRISPR Cures: The Economics of Genetic Therapies,” Innovative Genomics Institute, available at https://innovativegenomics.org/news/paying-for-crispr-cures/ (last visited March 12, 2026).
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