On Aug. 26, 2021, the Federal Circuit held the asserted claims of Sloan Kettering’s CAR-T patent invalid for lack of written description, reversing the final judgment of a California district court awarding Sloan Kettering and Juno (exclusive licensee) over $1.2 billion in damages. Juno Therapeutics, Inc., et al. v. Kite Pharma, Inc., No. 2020-1758 (Fed. Cir. Aug. 26, 2021). In April 2020, the district court denied Kite’s motions for JMOL, upholding the jury’s finding of willful infringement, and finding that Kite had not proven any of the asserted claims invalid for lack of written description and enablement.

The claims at issue covered a nucleic acid polymer encoding a chimeric T cell receptor having three parts, one of which is a binding element (i.e., scFv) that binds to the CD19 antigen, among other targets. On appeal, Kite argued that the asserted claims lacked written description because the patent does not disclose a representative species or common structural features of the claimed scFv genus, and there was inadequate written description for the claimed functional binding limitation because the asserted claims cover millions of billions of scFvs. Juno and Sloan Kettering responded that scFvs were well known, interchangeable, have common structural features, and the patent’s two working examples of scFvs were representative of all scFvs.

The Federal Circuit agreed with Kite and held that substantial evidence did not support the jury’s finding of adequate written description. It rejected Juno’s argument that Ariad is “irrelevant” because the claims are not method claims that recite a “newly-identified cellular function or mechanism of action.” Id. at *18. Juno argued that scFvs were not the invention. Id. The court explained that the test for written description is the same for a novel compound or a novel combination of known elements. It is also not changed regardless of whether the claim element is essential or auxiliary to the invention. 

It noted that the written description “contains no details about these scFv species beyond the alphanumeric designations J591 and SJ25C1 for a skilled artisan to determine how or whether they are representative of the entire claimed genus.” Id. at *9. The Federal Circuit further stated that “disclosure of one scFv that binds to CD19 and one scFv that binds to a PSMA antigen on prostate cancer cells in the manner provided in this patent does not provide information sufficient to establish that a skilled artisan would understand how to identify the species of scFvs capable of binding to the limitless number of targets as the claims require.” Id. at *9-10.

The Federal Circuit also held that the asserted patent did not disclose structural features common to the members of the genus because it “discloses only two scFv examples and provides no 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. That scFvs in general were well-known or have the same general structure does not cure that deficiency.” Id. at *15. The Federal Circuit did not reach Kite’s additional arguments on appeal, including lack of enablement. 

This decision builds on the Federal Circuit’s body of case law relating to functional claim elements. It affirms that the written description requirement applies to the same extent to all claim elements, whether a particular element is regarded as the invention or not. It is therefore particularly important in drafting and litigating biotech claims for practitioners to consider all functional elements, regardless of whether a particular functional element is newly invented.