Overview
In REGENXBIO Inc. v. Sarepta Therapeutics, Inc., No. 2024-1408 (Fed. Cir. Feb. 20, 2026), the Federal Circuit reversed the district court’s grant of summary judgment holding that patent claims relating to gene therapy technology were ineligible as directed to a natural phenomenon. The decision clarifies the patent eligibility inquiry for natural phenomena by elaborating on the “markedly different characteristics” test.
District Court Proceedings
At the district court, REGENXBIO asserted claims against Sarepta reciting a cultured host cell containing a recombinant nucleic acid molecule that comprises an adeno-associated virus (AAV) capsid sequence and a non-AAV sequence, where the two sequences are derived from different species. Both parties moved for summary judgment on patent eligibility under § 101. Sarepta prevailed, as the district court held that the claims were directed to a natural phenomenon. The district court reasoned that both sequences were naturally occurring and that combining them failed to render the claims patent eligible. REGENXBIO appealed.
Federal Circuit Decision
The Federal Circuit explained that it determines whether composition claims are directed to natural phenomena under the “markedly different characteristics” test articulated by the Supreme Court in Diamond v. Chakrabarty and applied in Ass’n for Molecular Pathology v. Myriad Genetics. That test inquires whether the claimed invention possesses “markedly different characteristics” from those found in nature. The court may also consider whether the invention has “potential for significant utility.”
The Federal Circuit determined that the claimed cells possessed markedly different characteristics from those found in nature and thus were patent eligible. The court reasoned that the claimed nucleic acid does not exist in nature, as splicing together sequences from two different species requires human intervention.
The Federal Circuit explained that the district court erred by focusing on individual claim elements (the two sequence components), rather than the claims as a whole. The Federal Circuit further explained that claim limitations cannot be disregarded even if they are conventional.
The court also noted that it was undisputed that the claimed cells possessed the potential for significant utility in gene therapy, as described by the patent’s specification. The court further confirmed that utility may be considered even if not explicitly recited by the claims.
Takeaways
This decision highlights that the markedly different characteristics test focuses on the claim as a whole, rather than individual limitations.
The decision also underscores that prosecutors should consider laying a foundation for patent eligibility arguments when drafting a specification. Helpful content may include explanations of how the invention (1) does not arise in nature, (2) differs from what does arise in nature, and (3) has the potential for utility. Prosecutors should further consider drafting claims to emphasize how they differ from what arises in nature. Similarly, litigators should consider seeking claim constructions that appropriately frame the comparison between the claimed invention and what arises in nature.
