Epizyme Inc v. GlaxoSmithKline LLC

1. Case Identification

• Case #: IPR2020-01577
• Patent #: 10,478,426
• Filed: September 4, 2020
• Petitioner(s): Epizyme, Inc.
• Patent Owner(s): GlaxoSmithKline LLC
• Challenged Claims: 1

2. Patent Overview

• Title: Methods of Treating Cancer
• Brief Description: The ’426 patent describes methods of treating hematologic cancer by administering a therapeutically effective amount of a substituted benzamide compound. The compounds are selected from a genus defined by a specific chemical formula and are intended to inhibit the activity of Enhancer of Zeste Homolog 2 (EZH2), an enzyme linked to cancer.

3. Grounds for Unpatentability

Ground 1: Claim 1 is anticipated by, or in the alternative obvious over, Kuntz.

• Prior Art Relied Upon: Kuntz (Patent 8,410,088).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kuntz anticipated every limitation of claim 1 under 35 U.S.C. §102 or, at a minimum, rendered it obvious under 35 U.S.C. §103. Kuntz allegedly discloses a method for treating hematologic cancers by administering compounds falling within the genus of the ’426 patent’s challenged claim. Specifically, Petitioner identified forty distinct compounds in Kuntz (e.g., Compound 1, Compound 44) that possess the core structure and all required substituent groups (R1, R2, R3, R4, R5, and R6) recited in claim 1. Kuntz explicitly teaches using these compounds to treat hematological cancers, including non-Hodgkin’s lymphoma, which is a species of the claimed genus of cancers. Kuntz also discloses administering a "therapeutically effective amount," a term used and defined similarly in both Kuntz and the ’426 patent. Petitioner asserted that each of the forty disclosed compounds in Kuntz provides a separate, enabling disclosure that anticipates or renders obvious claim 1.
  • Motivation to Combine (for §103 grounds): The motivation was explicit in Kuntz, which teaches using the disclosed compounds to treat cancer. For the obviousness alternative, Petitioner contended that even if Kuntz did not explicitly disclose the exact dosage ranges later claimed, a person of ordinary skill in the art (POSA) would have been motivated to optimize the disclosed ranges from Kuntz to arrive at a therapeutically effective amount for treating hematologic cancer patients. Kuntz's disclosure of overlapping dosage ranges and successful in vivo results for Compound 44 in treating human lymphoma cell lines in mice would have provided this motivation.
  • Expectation of Success (for §103 grounds): A POSA would have had a reasonable expectation of success in using Kuntz’s compounds to treat hematologic cancer. This expectation was supported by Kuntz's disclosure of bioassay data showing EZH2 inhibition for all forty compounds and in vivo data confirming that Compound 44 inhibited tumor growth in a specific hematologic cancer model.

4. Key Claim Construction Positions

• –NRaRb in R5 Need Not Be Identical To –NRaRb in R6: Petitioner argued that a POSA would interpret claim 1 as not requiring the amino group substituents (Ra and Rb) at the R5 position to be identical to the amino group substituents at the R6 position. Petitioner noted that a contrary construction would exclude all forty-eight examples disclosed in the ’426 patent itself, a result that is "rarely, if ever, correct."
• “therapeutically effective amount”: Petitioner asserted this term should be construed according to the patent’s explicit definition as "any amount which, as compared to a corresponding subject who has not received such amount, results in improved treatment, healing, prevention, or amelioration of a disease." This broad definition encompasses even modest results, such as marginally reducing tumor growth rates, which aligns with the disclosures in Kuntz.

5. Key Technical Contentions (Beyond Claim Construction)

• The ’426 Patent Is Subject to Post-AIA Law: A central contention was that the ’426 patent was not entitled to the priority date of its pre-AIA provisional application (GSK’s Provisional). This would make the patent subject to post-AIA "first-inventor-to-file" rules, rendering Kuntz indisputable prior art that cannot be antedated.
• Lack of Written Description Support in GSK’s Provisional: Petitioner argued GSK’s Provisional fails to provide adequate written description for the broad genus of claim 1. The provisional allegedly disclosed only a single species (Example 7) within the claimed genus, which covers over 100 septillion compounds. In a highly unpredictable field like EZH2 inhibitor development, this single example was argued to be non-representative. Furthermore, Petitioner contended the provisional lacked "blazemarks" to guide a POSA from the vast laundry lists of possible chemical substituents to the specific, arbitrarily selected subgenus of the challenged claim, thereby failing to demonstrate that the inventors were in possession of the claimed invention.

6. Arguments Regarding Discretionary Denial

• §325(d) Denial is Inappropriate: Petitioner argued that discretionary denial under §325(d) was improper because Kuntz, while of record, was never substantively considered or applied by the Examiner during prosecution of the ’426 patent or its parent applications. The Examiner’s allowance was based on the issuance of parent patents, which the Board had already found likely to be unpatentable over Kuntz in related IPR proceedings (IPR2020-00327 and IPR2020-00328).
• §314(a) Denial is Inappropriate: Petitioner argued this case is not an improper "follow-on" petition under the General Plastic factors. This was the first challenge to claim 1 of the ’426 patent, and the petition was filed promptly after it became possible to do so. Petitioner asserted that instituting review would promote efficiency, as the petition is nearly identical to an already-instituted IPR on the parent ’210 patent and addresses the same core issues.

7. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claim 1 of the ’426 patent as unpatentable.