Pfizer Inc v. Genentech Inc

1. Case Identification

• Patent #: 6,339,142
• Filed: August 29, 2017
• Petitioner(s): Pfizer, Inc.
• Patent Owner(s): Genentech, Inc.
• Challenged Claims: 1-3

2. Patent Overview

• Title: Protein Purification
• Brief Description: The ’142 patent specification describes methods for purifying polypeptides using ion exchange chromatography. However, the challenged claims are directed to a pharmaceutical composition comprising a mixture of an anti-HER2 antibody (trastuzumab, also known as humMAb4D5-8) and less than about 25% of its acidic variants.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over Andya - Claims 1-3 are invalid under 35 U.S.C. §102(b) as anticipated by, or in the alternative, obvious under §103 over Andya.

• Prior Art Relied Upon: Andya (International Publication No. WO 97/04801).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Andya discloses all limitations of the challenged claims. Andya describes stable lyophilized formulations of the anti-HER2 antibody humMAb4D5-8. It presents degradation data from cation-exchange chromatography (Figures 5-8) showing compositions with 78-82% native protein. Petitioner contended that the remaining 18-22% is degraded protein, which necessarily includes all acidic variants. Because the total degraded protein is 18-22%, the amount of acidic variants is inherently less than the claimed "about 25%." Andya also explicitly teaches formulating these compositions with pharmaceutically acceptable carriers (e.g., sodium succinate, trehalose), anticipating claim 2. The identity of the antibody as humMAb4D5-8 anticipates claim 3.
  • Motivation to Combine (for §103 grounds): As an alternative to anticipation, Petitioner asserted that it would have been obvious to a Person of Ordinary Skill in the Art (POSITA) to arrive at the claimed invention. Andya’s disclosure of compositions with 18-22% total degraded protein would have made it obvious that the subset of acidic variants was well below 25%, as deamidation (which forms acidic variants) is described as a major degradation route.
  • Expectation of Success (for §103 grounds): A POSITA would have had a high expectation of success, as Andya provides detailed examples and data for producing the exact compositions.

Ground 2: Anticipation and Obviousness over Waterside - Claim 1 is anticipated under §102(b), and claims 2-3 are obvious under §103 over Waterside.

• Prior Art Relied Upon: Waterside (slides from a 1996 conference presentation by Genentech).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Waterside, a public presentation by the Patent Owner, anticipates claim 1. Waterside presents chromatograms of rhuMAb HER2 (the same antibody as humMAb4D5-8) that separate the antibody into five peaks. Petitioner contended that peaks 1 and 2 represent the acidic variants. Based on both visual inspection and mathematical integration (using software like Data Thief), the combined area of these acidic peaks was calculated to be less than 25% of the total (e.g., 22%, 14%, and 24% in three separate lots). Waterside also provides data confirming that peak 1 contains a deamidated, and therefore acidic, variant of the antibody.
  • Motivation to Combine (for §103 grounds): Petitioner argued it would have been obvious to a POSITA to formulate the composition in Waterside with a pharmaceutically acceptable carrier (claim 2). Waterside disclosed that the antibody was already in Phase III clinical trials, which would strongly motivate a POSITA to prepare it in a stable, deliverable form for therapeutic use using well-known carriers. A POSITA would also have understood the rhuMAb HER2 in Waterside to be humMAb4D5-8 (claim 3), as it was the only such antibody matching the description in clinical development by Genentech at the time.
  • Expectation of Success (for §103 grounds): A POSITA would have expected success in formulating the antibody for therapeutic use, as this was a standard and necessary step for any drug in late-stage clinical trials.

Ground 3: Anticipation and Obviousness over Harris - Claim 1 is anticipated under §102(b), and claims 2-3 are obvious under §103 over Harris.

• Prior Art Relied Upon: Harris (a 1995 journal article published by Genentech).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner’s argument regarding Harris largely mirrored the argument for Waterside, as Harris published what appear to be the same chromatograms and data a year earlier. Harris discloses separating "three lots of rhuMAB HER2" using cation-exchange chromatography. It explicitly identifies peaks 1 and 2 as "the more acidic peaks" that are "deamidated at Asn30 in one light chain." Mathematical analysis of the chromatograms again showed these acidic variants constituted less than 25% of the total composition. Therefore, Harris was argued to anticipate every limitation of claim 1.
  • Motivation to Combine (for §103 grounds): For the same reasons articulated for Waterside, a POSITA would have been motivated to formulate the Harris compositions with pharmaceutically acceptable carriers (claim 2) to ensure stability and suitability for human therapeutic use. It would have also been obvious that the rhuMAb HER2 described in Harris was the clinically relevant humMAb4D5-8 (claim 3), given the context of Genentech’s research.
  • Expectation of Success (for §103 grounds): A POSITA would have readily expected to successfully formulate the antibody composition, as the purification and analysis methods were standard and the motivation to create a therapeutic product was clear.

4. Key Claim Construction Positions

• "A composition" (Preamble): Petitioner argued that the preamble term "A composition" is not a limitation. It asserted the phrase merely gives a descriptive name to the claimed elements and does not add any structural limitations, as the body of the claim describes a structurally complete invention (a mixture of an antibody and its variants).
• "Pharmaceutically acceptable carrier": Petitioner proposed that this term should be construed as "a non-toxic carrier to recipients at the dosages and concentrations employed." This construction is based on the patent’s own specification and was argued to be standard in the art. Petitioner contended that this term should not be interpreted to require that the composition has been "made on a full manufacturing scale."

5. Key Technical Contentions

• <25% Acidic Variant Level is Inherent: A central technical argument was that the "less than about 25%" limitation is not an inventive feature but rather an inherent property of applying standard purification techniques (like cation-exchange chromatography) to the known anti-HER2 antibody. The patent itself noted that an initial purification step resulted in "about 25%" acidic variants, suggesting the claimed range is not novel or unexpected.
• Identity of Antibody Across References: Petitioner asserted that a POSITA would have understood that the "rhuMAb HER2" described in the Harris and Waterside prior art references was the same as the "humMAb4D5-8" antibody recited in claim 3 and disclosed in Andya. This connection was crucial for mapping the prior art disclosures onto the specific antibody claimed.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-3 of the ’142 patent as unpatentable.