Neurocrine Biosciences Inc v. Spruce Biosciences Inc

1. Case Identification

• Case #: PGR2025-00032
• Patent #: 12,115,166
• Filed: February 10, 2025
• Petitioner(s): Neurocrine Biosciences, Inc.
• Patent Owner(s): Spruce Biosciences, Inc.
• Challenged Claims: 1-10 and 12-21

2. Patent Overview

• Title: CORTICOTROPIN RELEASING FACTOR RECEPTOR ANTAGONISTS
• Brief Description: The ’166 patent discloses methods for treating congenital adrenal hyperplasia (CAH) in a human. The methods involve administering a therapeutically effective amount of a corticotropin-releasing factor 1 (CRF1) receptor antagonist to achieve specific clinical outcomes, such as reducing the required dose of glucocorticoids and lowering levels of certain adrenal hormones.

3. Grounds for Unpatentability

Ground 1: Lack of Written Description under §112(a)

• Prior Art Relied Upon: This ground is based on the insufficiency of the ’166 patent’s specification itself.
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that the challenged claims are unpatentable for lacking adequate written description under 35 U.S.C. §112(a). The core of the argument was that the claims recite a broad, functionally defined genus encompassing any CRF1 receptor antagonist that can treat CAH and achieve specified clinical results. However, the specification only discloses a single species, tildacerfont ("Compound 1"), and fails to provide either a representative number of species or common structural features that would allow a person of ordinary skill in the art (POSA) to visualize or recognize the members of the claimed genus.
  • Key Aspects: Petitioner emphasized that the Board had previously issued Final Written Decisions (FWDs) in PGR2021-00088 and PGR2022-00025, finding all claims of two related patents from the same family (’908 and ’201 patents) unpatentable for lack of written description based on the same defective specification. Petitioner also argued that the ’166 patent’s claims are even more deficient because they include a stability limitation ("stable for storage for a minimum of six months"), for which the specification provides no support beyond data for the single disclosed compound, tildacerfont.

Ground 2: Lack of Enablement under §112(a)

• Prior Art Relied Upon: This ground is based on the insufficiency of the ’166 patent’s specification itself.
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that the claims are not enabled because the specification fails to teach a POSA how to make and use the full scope of the claimed invention without undue experimentation. The claims cover an entire class of compounds defined by their function—treating CAH and achieving specific clinical outcomes. Petitioner argued this provides nothing more than a "hunting license" requiring a laborious trial-and-error approach to identify other functional antagonists, a practice deemed insufficient for enablement by the Supreme Court in Amgen Inc. v. Sanofi.
  • Key Aspects: The argument was supported by an analysis of the Wands factors. Petitioner asserted that the vast breadth of the claims (encompassing a large and indeterminate number of compounds), the lack of guidance beyond the single disclosed (and clinically failed) species, the acknowledged unpredictability in the art of CRF1 antagonists, and the absence of a known structure-function relationship all weigh heavily against a finding of enablement. The petition asserted that a POSA would be forced to synthesize and screen a large number of candidates and then conduct costly and lengthy clinical trials to determine which, if any, fall within the claim scope.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial would be improper. Under §324(a), denial was not warranted as this is the first petition challenging the ’166 patent and no co-pending litigation exists.
• Denial under §325(d) was argued to be inappropriate because the substantive grounds of lack of written description and enablement were never raised or addressed by the Examiner during prosecution. Critically, Petitioner asserted the Examiner erred in allowing the claims without the benefit of the Board’s FWDs in two related PGRs, which found nearly identical genus claims unpatentable based on the same shared specification.

5. Relief Requested

• Petitioner requests institution of Post Grant Review and cancellation of claims 1-10 and 12-21 of the ’166 patent as unpatentable under 35 U.S.C. §112(a).