Functional claims took another hit at the Federal Circuit Court of Appeals. The patent at issue broadly claimed a three-part chimeric antigen receptor including all scFvs that bind to any target. The Court found written description lacking for failure to provide a representative sample of species falling within the claims or “defining characteristics” for the broad genus. The two lone examples in the specification were not representative of the broad claims and the patent failed to disclose structural features common to scFvs capable of binding specific targets. This decision is a stark reminder to include as much structural detail and as many examples in the patent as practicable, and also to include both claims to individual species and narrow genus claims tailored to the disclosed examples.

Background

The plaintiffs, Juno Therapeutics and the Sloan Kettering Institute for Cancer Research, alleged that Kite’s YESCARTA® therapy infringed U.S. Patent No. 7,446,190, entitled “Nucleic Acid Encoding Chimeric T Cell Receptors.” The therapy was developed by inventors at Sloan Kettering and licensed to Juno by a Sloan Kettering entity. YESCARTA® is a treatment for large B-cell lymphoma or follicular lymphoma, two types of non-Hodgkin lymphoma. At the time of the trial in 2019, YESCARTA® was one of only two FDA-approved CAR-T therapies.

In 2019, the jury had found the patent not invalid and rendered a damages verdict including a $535 million upfront payment and a 27.6% ongoing royalty. After post-trial motions, the court entered judgment against Kite and in favor Juno for approximately $1.2 billion. The Federal Circuit, however, concluded that the jury verdict regarding written description was not supported by substantial evidence, and reversed the judgment.

The claims in essence disclosed a three-part CAR (chimeric antigen receptor) with a costimulatory domain of a particular amino-acid sequence—amino acids 114 through 220 of a protein called CD28; a protein called CD3ζ as the primary signaling domain, and an scFv as a binding element. ScFvs are simplified antibodies for binding the reengineered CAR-T cells to the targeted cancer cells. An scFv consists of two pieces of an antibody’s variable regions that are linked together. Each variable region has a unique amino acid sequence that can dictate whether and how the scFv binds to a target.

The Written Description Requirement

Section 112 of the Patent Act provides that the patent specification “shall contain a written description of the invention,” requiring the specification to convey with reasonable clarity to those skilled in the art that the inventor was in possession of the invention as of the filing date. The necessary showing “varies with the nature and scope of the invention at issue, and with the scientific and technologic knowledge already in existence.” Capon v. Eshhar, 418 F.3d 1349, 1357 (Fed. Cir. 2005). For generic claims, the Federal Circuit has set forth “a number of factors for evaluating the adequacy of the disclosure, including ‘the existing knowledge in the particular field, the extent and content of the prior art, the maturity of the science or technology, [and] the predictability of the aspect at issue.’” Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc) (citing Capon, 418 F.3d at 1359). For genus claims using functional language, the description of the invention must show “that the applicant has invented species sufficient to support a claim to the functionally-defined genus.” Ariad, 598 F.3d at 1349.

The Patent Claims Lacked Written Description

The broadest asserted claims broadly covered as part of the claimed nucleic acid polymer encoding for the three-part CAR, any scFv for binding any target. The written description failed, however, to provide a representative sample of species falling within the claim or “defining characteristics” for the broad genus. The two lone examples in the specification were not representative of the broad claims.

Further, the specification lacked sufficient information about which scFvs could bind to which target antigens. While disclosing specific amino acid sequences of the scFvs was not necessary, the patent needed to provide some means of identifying which scFvs would bind to which targets, such as common structural characteristics or shared traits. Juno argued that the patent satisfied the written description requirement because all scFvs have a similar, common structure (two variable regions connected by a linker). Even though all scFvs have a common general structure, differences in the amino acid sequence in the variable regions would result in an scFv recognizing different antigens. The patent failed to disclose either structural features common to scFvs capable of binding specific targets, or a way to distinguish those scFvs capable of binding from scFvs incapable of binding those targets. It lacked details regarding the characteristics, sequences, or structures that would allow a person of ordinary skill in the art to determine which scFvs will bind to which target, despite scFvs being well-known in the art and having the same general structure.

The claims that were limited to scFvs that bind CD19 (a specific target) also lacked written description. The patent lacked details about any CD19-specific scFv, such as an exemplary amino acid sequence, a shape, or general characteristics that would allow this scFv to bind to the specified target. While scFvs in general were known, and even known to bind, the realm of possible CD19-specific scFvs was vast and the number of known CD19-specific scFvs was small (five at most). The patent lacked details as to which “which scFvs bind to CD19 in a way that distinguishes them from scFvs that do not bind to CD19.”