PTAB

PGR2025-00076

Gilgamesh Pharmaceuticals, Inc. v. Enveric Biosciences Canada, Inc.

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Halogenated Psilocybin Derivatives and Formulations
  • Brief Description: The ’276 patent describes halogenated psilocybin derivatives claimed under a generic Markush structure (Formula I) and related pharmaceutical compositions. The patent discloses preparing the compounds using a biosynthetic system with a psilocybin enzyme complement and asserts their utility for treating psychiatric disorders.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1-3, 13, and 20 over Soubhye

  • Prior Art Relied Upon: Soubhye et al., J. Med. Chem. 2010, 53, 8747-8759 (“Soubhye”).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Soubhye, which investigates 3-(aminoalkyl)-5-fluoroindole analogues as myeloperoxidase inhibitors, explicitly discloses multiple chemical species that fall within the scope of the challenged claims. Specifically, Soubhye’s compound 4 (5-fluorotryptamine) and compound 3 (5-chlorotryptamine) are species encompassed by the genus of claim 1. Soubhye further discloses derivatives of 5-fluorotryptamine with mono- and di-alkyl substitutions on the amine nitrogen (compounds 16-21), which Petitioner contended directly read on the limitations of dependent claims 2, 3, and 20. For example, compound 21 from Soubhye (N,N-diethyl-5-fluorotryptamine) meets all limitations of claim 1 where R5 is a halogen (fluoro) and R3a/R3b are alkyl groups (ethyl).

Ground 2: Anticipation of Claims 1-3, 9, 12-14, 16, 18-20, 24, 26, and 28 over USSN ‘075

  • Prior Art Relied Upon: USSN 62/978,075 (“USSN ‘075”), a provisional application with an effective filing date prior to the ’276 patent.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that USSN ‘075 describes numerous species of halogenated tryptamine compounds for treating mood disorders that anticipate a wide array of the challenged claims. The reference discloses specific compounds with halogen substitutions (F, Cl, Br) at the R4, R5, R6, and R7 positions of the indole ring, combined with various N,N-dialkyl substitutions (e.g., ethyl, propyl) on the amine side chain. Petitioner provided tables mapping these specific disclosed species to the elements of claims 1-3, 9, 12-14, 16, 18-20, 24, 26, and 28. For example, Petitioner argued that a disclosed N-ethyl-N-propyl-6-chlorotryptamine compound in USSN ‘075 anticipates claims 1, 2, 3, 13, 14, 16, 20, and 24. The application’s disclosure of pharmaceutical formulations containing these compounds was also argued to anticipate claim 28.

Ground 3: Obviousness of Claim 25 over WO ‘907 in view of US ‘010

  • Prior Art Relied Upon: WO 2018/106907 (“WO ‘907”) and US 2012/0029010 (“’010 application”).

  • Core Argument for this Ground:

    • Prior Art Mapping: Claim 25 depends from claim 17 and requires a di-halogenated tryptamine where the amine substituents (R3a and R3b) are both (C1-C6)-alkyl groups. Petitioner argued that WO ‘907 discloses a specific di-halogenated tryptamine (2-(5-chloro-6-fluoro-1H-indol-3-yl)ethan-1-amine, from Example 48) that was a commercially available starting material. This compound meets the limitations of the parent claims but has a primary amine (R3a and R3b are H). The ’010 application teaches that tryptamines, including di-halo-substituted tryptamines, can have N,N-dialkyl substitutions to achieve therapeutic properties, such as antidepressant and anxiolytic activity.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would have been motivated to modify the known di-halo tryptamine from WO ‘907 to improve its therapeutic properties. The ’010 application explicitly teaches that N,N-dialkylation of the tryptamine scaffold is a known strategy for this purpose.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in performing the N,N-dialkylation of the primary amine on the compound from WO ‘907. This is a routine and predictable chemical modification used to produce compounds with known therapeutic potential, as taught by the ’010 application.

  • Additional Grounds: Petitioner asserted numerous additional anticipation challenges against claims 1-20 and 24-29 based on specific compounds disclosed in Kalir (a 1966 journal article), Pelchowicz (a 1961 journal article), Patent 3,780,063, ’948 application, WO 2020/181194, and Julia (a 1967 journal article), among others. Petitioner also asserted obviousness grounds against specific compounds recited in claim 27.

4. Key Claim Construction Positions

  • Petitioner argued that the terms “alkyl,” “O-alkyl,” and “acyl” as used in claim 1 are indefinite under 35 U.S.C. §112. The specification defines these terms with a variable for the number of carbon atoms (“p” or “n”) but fails to define an upper limit for that variable. Petitioner contended this open-ended definition renders the claim scope unclear. Based on the examples provided in the specification, which show only C1-C6 groups, Petitioner proposed that the terms should be construed as being limited to 1 to 6 carbon atoms to lend clarity to the claims.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under 35 U.S.C. §325(d) is not appropriate. The prosecution history of the ’276 patent was simple and involved no substantive rejections based on prior art. Petitioner asserted that the extensive prior art cited in the petition—consisting of over a dozen references—was never presented to or considered by the Examiner. Because the petition relies on new art and arguments, Petitioner contended that institution would serve the public interest by allowing for a substantive review that did not previously occur.

6. Relief Requested

  • Petitioner requests institution of a Post Grant Review (PGR) and cancellation of claims 1-20 and 24-29 of the ’276 patent as unpatentable.