Why should we care about this case?

This case sits at the intersection of biotechnology innovation and “natural law” exceptions for patentable subject matter. It importantly implicates how broadly a patentee can claim “human-made organisms” or man-made modifications that were made to natural sequences. Numerous biotechnological/pharmaceutical companies rely on the types of man-made modifications that were declared patent ineligible by the district court.  If the district court’s decision is affirmed by the Federal court, it would undermine the validity of a wide array of biotech innovations and put U.S. biotech firms at a competitive disadvantage.

First, the case tests whether incorporation of features based on natural products into cells is sufficient for patent eligibility. 
Second, the dispute probes to what extent man-made changes to naturally occurring compositions must be explicitly included in patent claims to transform the claimed compositions into something that is patentable. Essentially - is a structural change enough or does there also need to be a change in function?

Third, it may affect how broadly patentees can claim an innovation, especially where claim elements arguably cover future, as‑yet‑unspecified applications.

The Federal Circuit’s resolution will influence claim drafting strategies for composition claims in biotechnology and could recalibrate how courts interpret broader claim elements.

Case Background

• Sarepta Therapeutics Inc. commercializes an FDA approved gene therapy product for the treatment of Duchenne muscular dystrophy (DMD) referred to as SRP-9001 (marketed as ELEVIDYS in the U.S.).
• REGENXBIO Inc. and The Trustees of the University of Pennsylvania (“Regenxbio”) sued Sarepta Therapeutics Inc. and Sarepta Therapeutics Three, LLC (“Sarepta”) alleging infringement of U.S. Patent No. 10,526,617 (“the ’617 patent”)
• The claims of the ’617 patent are directed to cultured host cells that are modified to contain a genetically engineered recombinant nucleic acid molecule that encodes for both a particular AAV capsid protein (AAVrh.10) – i.e., the outer shell of the gene therapy viral vector – and for a heterologous non-AAV sequence – i.e., a sequence from a non-AAV source. While the asserted claims do not cover ELEVIDYS itself, Regenxbio asserted patent infringement based on Sarepta’s use of the patented cultured host cell technology to make ELEVIDYS.
• Originally, Sarepta asserted that any use of the patented cultured host cells, as long as to develop ELEVIDYS, fell under the protections of 35 U.S.C. § 271(e)(1) (the “safe harbor”) which makes it not an infringement to make/use a patented product to generate data to submit to the FDA. Regenxbio countered that safe harbor was inapplicable because the patented cultured host cells were not subject to FDA approval.
• Sarepta also argued that the claims of the ’617 Patent are directed to naturally occurring AAV sequences.  Sarepta emphasized that the additional elements in the asserted claims identify the location of the rh.10 sequences after they have been removed from their naturally occurring source – i.e., they are attached to an unspecified “heterologous non-AAV” sequence and contained in generic “cultured host cells.” Regenxbio countered Sarepta’s argument by asserting that the claims are directed to “cultured host cells which must contain a recombinant nucleic acid molecule that encodes the sequence of AAVrh.10 (or a sequence at least 95% identical) and (emphasis added) a heterologous, non-AAV sequence” and such cells are not found in nature.
• The district court held the claims of the ’617 Patent are invalid because the isolated AAVrh.10 sequences are not “markedly different” from those found in nature and isolation alone is not sufficient to create patentable subject matter. The district court also wrote that the non-AAV sequence or any other elements of the claimed invention have not been altered from their naturally occurring counterparts. Essentially, the district court ignored the cultured host cell aspect and focused only on the AAV nucleic acid sequence element of the claim.

***Issues Presented in Appeal ***

• Regenxbio appealed to the Federal Circuit arguing that the cultured host cells are in fact “markedly different” from any natural product both structurally and functionally.
• Structurally, Regenxbio argues that the cultured host cells are not natural and can only be made through genetic engineering.
• Functionally, Regenxbio asserts that the cultured host cells can perform several functions that the native DNA sequences alone cannot (e.g., make and clone bacterial host cells; use in gene therapy applications; use in vaccination and serotyping; and potential research applications).

 

Oral Arguments Presented:

• The core dispute is whether the requirement of “markedly different” is satisfied by any structural variation from the natural sequences, or whether the variation must also impart a different function, and what all should be recited explicitly in the claims.
• Regenxbio positioned the claims as composition of matter claims requiring an artificial, genetically engineered, cultured host cell that includes an artificial, genetically engineered, recombinant nucleic acid molecule, which has nucleic acid material from two organisms chemically joined together into a single new nucleic acid molecule. They emphasized that Sarepta’ experts conceded these claimed compositions are not naturally occurring.
• Regenxbio argued that man‑made compositions with a markedly different structure suffice to establish patent eligibility, and that there is no legal requirement that any markedly different function be expressly recited as a claim limitation. They stressed that structure and not recitation of function drives the patent eligibility analysis.
• One of the Federal Circuit judges pressed Regenxbio on the breadth of the claims by noting “rh.10 attached to anything that isn’t an [adeno-associated virus] is patentable is an incredibly broad claim that reaches things that are unknown at this point.”  In other words, the claims appear to reach “any” heterologous non‑AAV sequence fused to AAVrh.10 for “any” purpose, encompassing unknown future applications. One judge characterized the dispute as an “over‑claiming” problem—capturing more than what was invented.
• Sarepta argued the claims are, in substance, directed to the naturally occurring AAVrh.10 sequence and the additional claim elements (e.g., the cultured host cell and the heterologous non‑AAV inserts) do not add any meaningful changes to the AAV sequence. Sarepta framed the additional elements as high‑level, conventional, and well-known, rendering the claims tantamount to mere isolation and storage of the natural sequence.
• One of the Federal Circuit judges asked Sarepta whether “we should just act as if that language [heterologous non-AAV sequence] is not even in the claim?” and Sarepta responded that the language was “not markedly different from isolating the DNA, taking it out of its natural environment” - essentially noting that the language was meaningless.