PTAB

IPR2019-01455

Gilead Sciences, Inc. v. United States of America

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1. Case Identification

2. Patent Overview

  • Title: Methods for Chemoprophylaxis of Retroviral Infection
  • Brief Description: The ’191 patent relates to methods for preventing immunodeficiency virus infection in primates. The methods involve administering a combination of antiretroviral agents, specifically tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC), to an uninfected subject prior to a potential exposure to the virus.

3. Grounds for Unpatentability

Ground 1: Anticipation over Cal-PrEP - Claims 1-19 are anticipated by Cal-PrEP under 35 U.S.C. §102(b).

  • Prior Art Relied Upon: Szekeres et al., “Anticipating the Efficacy of HIV Pre-Exposure Prophylaxis (PrEP) and the Needs of At-Risk Californians,” (Nov. 2004) (“Cal-PrEP”).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Cal-PrEP, a 2004 report, described every element of the challenged claims. Cal-PrEP taught a method of pre-exposure prophylaxis (PrEP) where antiretroviral drugs are used by an individual "prior to potential HIV exposure to reduce the likelihood of infection." The report specifically identified the combination of TDF and FTC, marketed as Truvada®, as a preferred, once-daily oral tablet for this purpose. Petitioner asserted that Cal-PrEP taught selecting HIV-uninfected individuals from high-risk populations (e.g., adult males) and administering the TDF/FTC combination in tablet form, thereby expressly teaching the limitations of independent claims 1 and 13 and the additional limitations of the dependent claims.

Ground 2: Obviousness over CDC-PEP and Cal-PrEP - Claims 1-19 are obvious over CDC-PEP in view of Cal-PrEP under 35 U.S.C. §103.

  • Prior Art Relied Upon: Centers for Disease Control and Prevention, “Antiretroviral Postexposure Prophylaxis After Sexual, Injection-Drug Use, or Other Nonoccupational Exposure to HIV in the United States,” (Jan. 2005) (“CDC-PEP”), in view of Cal-PrEP.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that CDC-PEP, a widely followed 2005 guideline, described post-exposure prophylaxis (PEP) and recommended a TDF/FTC combination (Truvada®) as a "preferred" backbone regimen to be administered after an HIV exposure to prevent infection. Cal-PrEP provided the rationale for shifting this prophylactic strategy to pre-exposure administration for individuals at high risk of repeated exposure. Petitioner contended that combining the teachings—using the drug combination from CDC-PEP for the pre-exposure purpose taught by Cal-PrEP—rendered all claims obvious.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would have been motivated to modify the PEP regimen of CDC-PEP to a PrEP regimen. Petitioner asserted the motivation was to maximize prophylactic effectiveness; if the drugs are effective when given within 72 hours after exposure, a POSITA would recognize that having therapeutic concentrations at the exposure site before or at the moment of exposure would be even more effective. Cal-PrEP provided a specific, community-focused motivation: administering PrEP to high-risk individuals would reduce overall HIV transmission rates, a goal not achievable with PEP alone.
    • Expectation of Success: Petitioner argued a POSITA would have had a reasonable expectation of success. The pharmacological mechanism of TDF/FTC is identical whether used for PrEP or PEP. The extensive clinical experience and data supporting the effectiveness of PEP, as detailed in the CDC-PEP guidelines, provided strong evidence that the drug combination was effective at preventing HIV infection, making it predictable that this efficacy would extend to a pre-exposure context.

4. Key Claim Construction Positions

Petitioner argued that several claim terms required construction to properly assess patentability.

  • “[P]rotecting a primate host...” and “inhibiting establishment of...infection”: Petitioner contended that these preamble and "thereby" clauses were non-limiting statements of intended result. They argued the clauses do not add any manipulative steps to the method but merely describe the desired outcome of performing the core operative steps of selecting a subject and administering the drug combination. Therefore, the patentability analysis should focus on whether the prior art taught the operative steps themselves.
  • “[S]elf-replicating infection”: Petitioner proposed this term should be construed to mean "an HIV infection that can no longer be suppressed solely by the host’s immune system." This definition aligns with the known virology where infection becomes established approximately 72 hours after exposure, a critical timeframe for both PEP and PrEP.
  • “[P]rior to the exposure” / “prior to a potential exposure”: Petitioner argued this language does not require administration before the first-ever HIV exposure. Instead, it should be understood to mean prior to any given exposure. This construction is crucial for high-risk individuals who face repeated potential exposures, as described in the prior art, and ensures the claims cover ongoing prophylactic use.

5. Arguments Regarding Discretionary Denial

Petitioner argued the Board should not exercise its discretion to deny institution under 35 U.S.C. §325(d).

  • Petitioner asserted that it presented different grounds and new evidence not previously considered by the USPTO, including the Cal-PrEP and CDC-PEP references and an expert declaration from Dr. Michael Youle.
  • Petitioner further contended that the Examiner erred during prosecution. The Examiner allegedly allowed the claims after the Applicant added a "tablet" limitation, but failed to recognize that the prior art (Cal-PrEP) already disclosed using Truvada, which is a tablet. Petitioner argued the Examiner mistakenly equated the rejection based on Cal-PrEP and CDC-PEP with a previous rejection based on different, less relevant art, and never properly addressed the substantive teachings of the references cited in the petition.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-19 of Patent 9,937,191 as unpatentable.