Gilead Sciences Inc v. United States

1. Case Identification

• Case #: IPR2019-01455
• Patent #: 9,937,191
• Filed: August 23, 2019
• Petitioner(s): Gilead Sciences, Inc.
• Patent Owner(s): The United States of America, as represented by the Department of Health and Human Services
• Challenged Claims: 1-19

2. Patent Overview

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

3. Grounds for Unpatentability

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

• Prior Art Relied Upon: Cal-PrEP (a 2004 report from the Center for HIV Identification, Prevention and Treatment Services and AIDS Partnership California).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Cal-PrEP disclosed every limitation of the challenged claims. Cal-PrEP described pre-exposure prophylaxis (PrEP) as a "novel approach to HIV prevention in which antiretroviral drugs (ARVs) are used by an individual prior to potential HIV exposure." It specifically identified TDF as the "most suitable" drug for PrEP and explicitly named Truvada® (a once-daily, fixed-dose combination tablet of TDF and emtricitabine) as a TDF-based product approved in August 2004 for this use. Petitioner contended this teaching directly maps to independent claims 1 and 13, which require selecting an uninfected host and administering a combination of TDF and FTC prior to exposure.
  • Prior Art Mapping (Dependent Claims): Petitioner further argued that Cal-PrEP's focus on high-risk populations, such as men who have sex with men (MSM), anticipated claims directed at adult human males (claims 2-3). Its specific identification of Truvada as a single oral tablet anticipated claims requiring a "combined single tablet" (claims 4, 14, 17) and the FDA-approved dosages of 200 mg FTC and 300 mg TDF (claims 8, 12, 18). Cal-PrEP's discussion of daily administration in clinical trials for periods of 9 to 24 months was argued to meet the limitations of daily administration for "several days, weeks or months" (claims 9, 10, 19).

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

• Prior Art Relied Upon: CDC-PEP (a January 2005 CDC guidance document on post-exposure prophylaxis) and Cal-PrEP.
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that CDC-PEP taught the core elements of the claimed method but for a different timing of administration. CDC-PEP recommended a 28-day course of antiretrovirals administered after an HIV exposure (post-exposure prophylaxis, or PEP) to prevent infection. Crucially, it identified a TDF+FTC combination (i.e., Truvada) as one of two "preferred" backbone regimens for PEP. Cal-PrEP supplied the teaching of administering these same drugs before an exposure (PrEP) to high-risk individuals.
  • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would have been motivated to modify the timing of the established CDC-PEP regimen based on the teachings of Cal-PrEP. The motivation was to achieve maximum prophylactic effectiveness. A POSITA would have recognized that administering the antiretrovirals before an exposure, rather than after, would establish suppressive drug concentrations at the site of exposure at the exact moment it occurs, which is theoretically the optimal approach. Cal-PrEP provided the specific rationale for this modification: to reduce HIV infection rates in high-risk communities where individuals face repeated exposures.
  • Expectation of Success: Petitioner contended there was a strong and reasonable expectation of success. The extensive scientific and clinical experience with PEP, as documented in CDC-PEP, had already established that the TDF+FTC combination was effective at preventing HIV infection after exposure. Since PrEP involves the same drugs, same dosages, and same pharmacological mechanism, a POSITA would have reasonably expected that simply shifting the administration time to before exposure would be at least as effective, if not more so.

4. Key Claim Construction Positions

• "protecting a primate host from a self-replicating infection" / "inhibiting establishment of a...self-replicating infection": Petitioner argued these phrases in the preambles and "thereby" clauses of the independent claims were non-limiting statements of intended result. They described the goal of the method but did not impose a requirement that the method be 100% effective in every patient. This construction was central to the argument that prior art teaching the administration of Truvada for prophylaxis was anticipatory, even if it also discussed ongoing clinical trials to determine population-level effectiveness.
• "[P]rior to the exposure" / "prior to a potential exposure": Petitioner argued these terms did not limit the administration to occurring before the first ever HIV exposure an individual might experience. Instead, the terms should be construed to mean that for any given exposure, the drug administration occurred beforehand. This was relevant for high-risk individuals who may have multiple exposures over time.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the Board should not exercise its discretion to deny institution under 35 U.S.C. §325(d). The petition asserted that it presented different grounds (including anticipation) and new evidence (an expert declaration) that were not considered during the original examination. Furthermore, Petitioner argued that the Examiner made a clear error during prosecution by failing to properly consider the substantive teachings of Cal-PrEP and CDC-PEP, even after they were cited. The Examiner allegedly equated the prior art of record with less relevant art from a parent application's prosecution, thereby failing to appreciate the strength of the obviousness case presented by the combination.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-19 of the ’191 patent as unpatentable.