Fed. Circuit Upholds Gene Patents Under Section 101 in REGENXBIO
The patent eligibility of genetically engineered products remains a highly litigated issue in intellectual property law. The boundary separating unpatentable natural phenomena from patent-eligible compositions of matter requires careful judicial review.
The United States Court of Appeals for the Federal Circuit provided additional direction on this boundary in a recent precedential decision touching on section 101, without diving deep in the Alice/Mayo waters.
The opinion by Judge Stoll, writing for a panel joined by Judge Dyk and Judge Hughes, reversed a district court grant of summary judgment, determining that cultured host cells containing human-made recombinant nucleic acid molecules are patent-eligible. REGENXBIO Inc. v. Sarepta Therapeutics, Inc., No. 24-1408 (Fed. Cir. Feb. 20, 2026).
This ruling generally affirms the availability of patent protection for engineered biological vectors, when claimed appropriately.
Background of the Dispute
Genetic disorders occur when mutations or deletions exist within the nucleotide sequences of a person’s DNA. (Slip Op., p. 2). Medical science addresses these disorders through gene therapy. This therapy uses modified virus vectors to deliver a therapeutic gene, known as a transgene. The transgene replaces the defective or missing gene in a patient with, e.g., cystic fibrosis, hemophilia, or sickle cell anemia.
To create these vectors, scientists engineer host cells to contain plasmids. Plasmids are circular pieces of DNA separate from the host cell’s chromosomes. These plasmids contain the desired transgene. The host cell makes multiple copies of the plasmid and proliferates to produce additional host cells. The plasmids can contain a capsid sequence, representing the outer shell of the vector. Scientists purify and collect these plasmids, introducing them into a mammalian host cell to generate the gene therapy vector (pp. 2-3).
REGENXBIO Inc. and The Trustees of the University of Pennsylvania asserted U.S. Patent No. 10,526,617 against Sarepta Therapeutics, Inc. and Sarepta Therapeutics Three, LLC. The patent claims a cultured host cell containing a recombinant nucleic acid molecule. This recombinant molecule encodes an adeno-associated virus (AAV) vp1 capsid protein sequence and a heterologous non-AAV sequence. The term “heterologous” means the genetic material originates from a different species (p. 4).
REGENXBIO alleged that Sarepta infringed the patent by using an AAV variant in cultured host cells to produce a gene therapy product for Duchenne muscular dystrophy. In the United States District Court for the District of Delaware, Sarepta moved for summary judgment of patent ineligibility under 35 U.S.C. § 101. The district court granted the motion.
The lower court reasoned that the individual naturally occurring components in the claims remained unchanged. The district court held that combining natural products within a host cell fails to create a patentable invention, drawing an analogy to the unpatentable bacteria mixture in Funk Brothers Seed Co. v. Kalo Inoculant Co. (p. 6). REGENXBIO appealed this decision.
The Court’s Analysis
The central legal issue before the Federal Circuit centered on whether a host cell modified to contain a recombinant nucleic acid molecule constitutes a patent-eligible composition of matter or an unpatentable natural phenomenon. The Federal Circuit held that the claims are not directed to a natural phenomenon. The appellate court reversed the district court’s decision and remanded the case.
The Federal Circuit applied the “markedly different characteristics” framework established by the Supreme Court in Diamond v. Chakrabarty. The appellate panel concluded the district court applied an incorrect analytical method. The lower court improperly focused on the individual components of the claimed invention. The correct inquiry mandates examining whether the claimed composition as a whole exists in nature.
The Federal Circuit noted that a recombinant nucleic acid molecule is created by artificially splicing together nucleic acid sequences from at least two different organisms. A multi-step process is required to create recombinant DNA, involving cleaving DNA fragments, joining them with ligases, ligating the sequence into a plasmid, transforming a host cell, and purifying the extracted DNA (pp. 4-5). This human-directed process produces a composition absent from the natural environment. The court rejected the argument that the invention merely packaged natural components together.
The opinion reviews the Supreme Court’s decisions in Chakrabarty, Funk Brothers, and Association for Molecular Pathology v. Myriad Genetics, Inc. In Chakrabarty, the Supreme Court held that a genetically engineered bacterium capable of breaking down crude oil components possessed markedly different characteristics from any natural bacteria (p. 8). The invention constituted a product of human ingenuity.
In Funk Brothers, a mixed culture of naturally occurring root-nodule bacteria fell within the law of nature exception. The bacteria in that mixture continued to perform their natural functions without any change or improvement (pp. 8-9).
In Myriad, the Supreme Court distinguished between isolated naturally occurring DNA and complementary DNA (cDNA). The act of isolating DNA did not create anything new, rendering it patent-ineligible. The creation of a cDNA sequence, lacking naturally occurring non-coding regions, resulted in a distinct, non-naturally occurring molecule eligible for patent protection (pp. 9-10).
Applying these precedents, the Federal Circuit directly compared the claimed invention to the eligible cDNA claims in Myriad. The court articulated its reasoning clearly:
“Like the cDNA claims in Myriad, ‘the lab technician unquestionably creates something new’ when she splices together the claimed recombinant nucleic acid molecule that encodes an AAV vp1 capsid protein and a heterologous non-AAV sequence and inserts said molecule into a host cell.” (p. 13)
The court criticized the district court’s reliance on Funk Brothers. Scientists engineered two nucleic acid sequences from separate species into a single molecule and transformed a host cell to incorporate that new molecule.
The Federal Circuit determined this process creates a cell containing a molecule that could never form in nature independently. The court found this action materially different from growing naturally occurring bacteria strains in a culture where the bacteria undergo no change (pp. 14-15).
The appellate court evaluated the utility of the claimed invention. Chakrabarty and its progeny require a nonnaturally occurring composition of matter to possess “the potential for significant utility.” The Federal Circuit found it undisputed that the claimed compositions deliver genes to selected host cells and gene therapy patients (p. 16). The court held that the utility of the invention supports its eligibility, even if the utility remains an unclaimed functional distinction.
The Federal Circuit addressed its prior decision in ChromaDex, Inc. v. Elysium Health, Inc. In that case, the court invalidated claims directed to an isolated vitamin found in milk. The isolated vitamin lacked characteristics markedly different from the natural milk composition. The claims merely recited an increase in a biological process already occurring in natural milk without attributing that increase to the isolated vitamin (pp. 11-12). Sarepta argued that ChromaDex precluded considering unclaimed functional distinctions during the Chakrabarty inquiry. The Federal Circuit disagreed.
The appellate court clarified that ChromaDex involved claims expressly defining the structure of the composition by its overall function. The REGENXBIO claims do not suffer from this defect. The claimed host cells contain molecules entirely absent from nature. The court concluded that evaluating unclaimed functional distinctions remains permissible under Chakrabarty, supporting the eligibility of the gene therapy vectors (p. 17).
Sarepta attempted to recharacterize the claims as merely isolating the AAV sequence. The Federal Circuit rejected this attempt, pointing out that the claim language requires a cultured host cell, a heterologous nucleic acid sequence, and a recombinant nucleic acid molecule. The court declined to dissect the claims into old and new elements and ignore the old elements during the Section 101 analysis (p. 18).
Key Takeaways and Practical Implications
The Federal Circuit’s decision offers concrete guidance for patent practitioners drafting claims for biotechnological inventions. The ruling validates claiming engineered biological compositions, provided the claims recite specific elements incapable of forming naturally without human intervention.
Practitioners should draft claim language highlighting the structural differences between the claimed invention and naturally occurring biological materials. Reciting recombinant molecules, heterologous sequences, or specific artificial combinations helps establish the “markedly different characteristics” required by the Chakrabarty standard. Prosecutors must verify the claims reflect the entirety of the engineered composition. The Federal Circuit confirmed that courts must evaluate the composition as a whole rather than parsing out individual naturally occurring components.
Patent prosecutors can use this precedent to overcome Section 101 rejections from the United States Patent and Trademark Office. Applicants should detail the human-directed steps required to create the claimed composition. The opinion establishes that an invention’s utility factors into the eligibility analysis. Prosecutors should draft patent specifications that clearly articulate the specific utilities and functional advantages of the engineered compositions. The Federal Circuit recognized the gene delivery utility of the claimed host cells as a valid component of the Chakrabarty inquiry.
The clarification regarding ChromaDex provides additional strategic value. Patent drafters can rely on structural differences to satisfy Section 101 without expressly reciting functional limitations in the claims, provided the specification clearly establishes the invention’s utility. This reduces the risk of creating overly narrow claims burdened by functional limitations. This approach contrasts with the rejected claims in ChromaDex, where the structural similarity to natural milk required the patentee to rely on functional claim limitations to argue for eligibility.
For litigation strategies, this case creates a strong defense against attempts to invalidate genetically engineered compositions. Defendants frequently attempt to break down complex biological claims into their natural components.
The court provided further clarity regarding how these structural differences interact with the Alice/Mayo two-step framework. The appellate panel determined that establishing markedly different characteristics under Chakrabarty means the claims are not directed to a natural phenomenon at step one of Alice/Mayo. By resolving the eligibility question at step one, patent owners bypass the complicated step two evaluation for an inventive concept.
Plaintiffs can rely on this decision to argue that combining genetic material from different species to create a new host cell satisfies the requirements of Section 101 at step one of the Alice/Mayo framework. The Federal Circuit explicitly noted that finding the claims eligible at step one eliminates the need to consider step two of the framework (p. 19).
Conclusion
REGENXBIO Inc. v. Sarepta Therapeutics, Inc. affirms patent eligibility for engineered biological products. The Federal Circuit corrected a misapplication of the natural phenomenon exception.
By systematically applying Supreme Court precedents like Chakrabarty, Funk Brothers, and Myriad, the appellate court provided necessary doctrinal clarity. Addressing these prior cases instructs lower tribunals from improperly equating genuinely engineered biological compositions with unpatentable natural mixtures. This correction likely limits eligibility disputes and preserves intellectual property protection for complex gene therapy vectors.
It is no secret that pharmaceutical developers rely on secure intellectual property rights to fund the expensive, high-risk clinical trials required for these advanced therapies. Without predictable patent eligibility for engineered delivery vectors, the financial incentive to develop targeted cures for rare genetic disorders would severely diminish.
The legal frameworks governing intellectual property must maintain clear distinctions between discoveries of natural principles and human-made inventions. On first blush, this ruling maintains a pragmatic balance, securing patent rights for human ingenuity in the biotechnology sector.
Disclaimer: This is provided for informational purposes only and does not constitute legal or financial advice. To the extent there are any opinions in this article, they are the author’s alone and do not represent the beliefs of his firm or clients. The strategies expressed are purely speculation based on publicly available information. The information expressed is subject to change at any time and should be checked for completeness, accuracy and current applicability. For advice, consult a suitably licensed attorney and/or patent professional.