Lack of written description, enablement forces CAFC to kill Cancer Treatment Patent Claims
Lack of written description, enablement forces CAFC to kill Cancer Treatment Patent Claims
Filed in 2004, the parent patent application, claims a cancer treatment with a peptide subcomponent of a protein linking an antibody with a cytotoxic drug.
The U.S. Court of Appeals for the Federal Circuit has issued a precedential ruling in Seagen Inc. v. Daiichi Sankyo Co., Ltd., withdrawing the Eastern District of Texas’ denial of judgment as a matter of law (JMOL) that Seagen’s patent claims lacked both written description support and enablement. The appellate court applied precedents from both the US Supreme Court and Federal Circuit’s predecessor, the Court of Customs and Patent Appeals (CCPA), and found that Seagen’s disclosure on the original patent application claiming its antibody-drug conjugate cancer treatment was too broad to give the later-filed patent-at-issue the original application’s priority date, and also needed undue experimentation to discover effective drug combinations.
Seagen in July 2019 filed a continuation patent application resulting in the issuance of U.S. Patent No. 10808039, Monomethylvaline Compounds Capable of Conjugation to Ligands. Filed in 2004, the parent patent application, claims a cancer treatment with a peptide subcomponent of a protein linking an antibody with a cytotoxic drug. The drug moiety containing the cytotoxic cell-killing drug is released after the cancer cell is targeted by the antibody, improving selectivity in treatment. The continuation application resulting in the ‘039 patent, which includes AstraZeneca’s Enhertu cancer treatment, openly discloses a “Gly/Phe-only tetrapeptide,” a four-amino-acid-long unit where each amino acid is either glycine or phenylalanine, a protein not disclosed in the 2004 application.
The parties at trial in Eastern Texas argued whether the ‘039 patent was entitled to the priority date of the 2004 patent application, which would result in Enhertu invading the asserted patent claims, or if Enhertu was instead cancelling prior art made publicly known in December 2015. After the jury’s wilful infringement verdict, which awarded an upfront royalty of $41,820,000 and an 8% running royalty, Daiichi Sankyo filed for JMOL, arguing the written description and enablement issues under 35 U.S.C. § 112 discussed in the CAFC ruling.
The 1997 ruling of the Federal Circuit in Lockwood v. American Airlines establishes that, for a later-filed patent ‘to gain the benefit’ of an earlier application’s priority date, that application must reveal the invention ‘in the manner provided by [Section 112].’ Daiichi Sankyo on appeal argued that the 2004 application did not sufficiently disclose the Gly/Phe-only tetrapeptide corresponding to claim 1’s recitation of a “–WW–unit” serving as the linker protein.
The Federal Circuit noted as described in the 2004 patent application, that the WW unit, ‘when present’ could include anywhere from two to twelve amino acids. When considering the different amino acids that could determine the identity of the Ww unit and their isomers, ‘just with respect to tetrapeptides, over 47 million different tetrapeptide units’ are included, a point confirmed by expert witnesses for both sides. The appellate court acknowledged that its own case law reliably finds that the disclosure of a broad genus does not satisfy the written description requirement for claims directed to a particular subgenus.
The 2004 application contained “blaze marks” directing skilled artisans to the claimed Gly/Phe-tetrapeptide subgenus; Seagen also argued. At trial, Seagen’s expert on this issue claimed that a skilled artisan would find it a ‘straightforward leap’ to change the glycine-phenylalanine-leucine-glyice (GFLG) exemplary tetrapeptide from the 2004 application to the Gly/Phe-tetrapeptide claimed by the ‘039 patent. As the appellate court reportedly noted, ‘that testimony dooms Seagen’s case’ as it admits that a skilled artisan would not understand the inventors of the 2004 application to be in possession of the ‘039 patent’s tetrapeptides, providing insufficient evidence for a reasonable jury to find written description support. The CAFC reportedly said, “In sum, the 2004 application’s broad disclosure of effectively countless options for the peptide unit fails to show the subgenus of Gly/Phe-only tetrapeptides claimed in the ’039 patent.”
No reasonable jury could find that the ‘039 patent enabled a skilled artisan to make and use the full scope of the claimed invention; the Federal Circuit also ruled. The appellate court analogized to the U.S. Supreme Court’s ruling in Amgen v. Sanofi (2023), in which the Court found that Amgen’s entire genus of antibodies for a claimed cholesterol treatment was not enabled by the specification’s disclosure of two methods for testing if particular antibodies performed recited functions. Due to the unpredictability of antibody science, the Court found that without disclosing ‘a quality common to every functional embodiment,’ Amgen’s patent required trial-and-error discovery by skilled artisans. Here, due to similar unpredictability in intracellular cleaving of drug moieties, the Federal Circuit found that “a skilled artisan would be left to perform far-ranging ‘trial-and-error discovery’ to make and use the [antibody-drug conjugates] within the scope of the ’039 patent.”
The CAFC found the remaining arguments unpersuasive and concluded that the ‘039 patent is invalid for failing to meet the written description and enablement requirements. The appellate court vacated the jury’s wilful infringement and damages verdict.
