DCT

1:19-cv-06607

Ajanta Pharma Ltd v. Pfizer Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:19-cv-06607, S.D.N.Y., 07/16/2019
  • Venue Allegations: Venue is alleged to be proper based on Defendants' marketing and sales of pharmaceutical products, including Chantix®, in the district, and on Defendants having previously filed patent infringement suits in the district.
  • Core Dispute: Plaintiff seeks a declaratory judgment that its proposed generic varenicline drug product does not infringe, and/or that Defendants' patents covering specific tartrate salt forms of varenicline are invalid.
  • Technical Context: The technology involves creating specific, stable crystalline salt forms (polymorphs) of a pharmaceutical compound to improve its suitability for formulation and manufacturing as a commercial drug product.
  • Key Procedural History: This is a declaratory judgment action filed under the Hatch-Waxman Act by a generic drug manufacturer after the patent holder, Pfizer, received a Paragraph IV notice letter but did not file an infringement suit within the statutory 45-day period. The complaint notes that Pfizer has previously sued other generic manufacturers, Apotex Inc. and Mylan Pharmaceuticals Inc., for infringing the same patents-in-suit.

Case Timeline

Date Event
2001-05-14 Priority Date ('927 & '119 Patents)
2005-05-10 U.S. Patent No. 6,890,927 Issued
2007-09-04 U.S. Patent No. 7,265,119 Issued
2012-05-15 Apotex Inc. receives tentative ANDA approval
2013-05-03 Mylan Pharmaceuticals Inc. receives tentative ANDA approval
2019-03-05 Ajanta transmits Paragraph IV Notice Letter to Pfizer
2019-07-16 Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,890,927 - Tartrate Salts of 5,8,14-Triazateracyclo[10.3.1.02,11.04,9]-Hexadeca-2(11),3,5,7,9-Pentaene And Pharmaceutical Compositions Thereof (Issued May 10, 2005)

The Invention Explained

  • Problem Addressed: The patent explains that while the base chemical compound (varenicline) is useful for treating central nervous system disorders, many of its salt forms are 'so significantly hygroscopic as to render them poor candidates for pharmaceutical formulation use' ('927 Patent, col. 9:20-25). High hygroscopicity (the tendency to absorb moisture from the air) can compromise the stability, shelf-life, and manufacturability of a drug.
  • The Patented Solution: The invention is the discovery of specific tartrate salts of varenicline that possess superior physical properties, including high solid-state stability and low hygroscopicity, which 'render it superior to previously known salts' of the compound ('927 Patent, col. 2:22-30). These improved characteristics make the tartrate salts, particularly the L-tartrate salt, well-suited for use in a commercial pharmaceutical product ('927 Patent, col. 9:25-30).
  • Technical Importance: Identifying a stable, non-hygroscopic, and manufacturable salt form is a critical and often non-trivial step in pharmaceutical development that enables a promising active ingredient to become a viable commercial drug.

Key Claims at a Glance

The complaint seeks a declaratory judgment regarding "the claims" of the patent without specifying them (Compl. ¶50). The broadest independent claim is analyzed below.

  • Independent Claim 1:
    • The tartrate salt of 5,8,14-triazatetracyclo[10.3.1.02,11.04,9]-hexadeca-2(11),3,5,7,9-pentaene.

U.S. Patent No. 7,265,119 - Tartrate Salts of 5,8,14-Triazatetracyclo[10.3.1.02,11.04,9]-Hexadeca-2(11),3,5,7,9-Pentaene And Pharmaceutical Compositions Thereof (Issued September 4, 2007)

The Invention Explained

  • Problem Addressed: As with the parent ’927 Patent, this patent addresses the need for a stable, manufacturable form of the varenicline compound, noting that different crystalline forms, or polymorphs, of a drug can have distinct physical properties ('119 Patent, col. 9:35-40).
  • The Patented Solution: The patent discloses and claims specific crystalline polymorphs of the L-tartrate salt of varenicline, identified as Forms A, B, and C ('119 Patent, Abstract). These specific forms are characterized by unique fingerprints, such as their powder X-ray diffraction (PXRD) patterns, which confirm their distinct and stable crystalline structures suitable for pharmaceutical use ('119 Patent, col. 10:4-11). Figure 1, for example, shows the distinct PXRD pattern for the anhydrous L-tartrate salt Form A ('119 Patent, Fig. 1).
  • Technical Importance: Patenting specific polymorphs provides a further layer of protection for a drug product, as a later-developed polymorph can be a non-obvious invention over a previously known form if it possesses unexpectedly superior properties.

Key Claims at a Glance

The complaint seeks a declaratory judgment regarding "the claims" of the patent without specifying them (Compl. ¶50). The first independent claim is analyzed below.

  • Independent Claim 1:
    • The anhydrous L-tartrate salt of 5,8,14-triazatetracyclo[10.3.1.02,11.04,9]-hexadeca-2(11),3,5,7,9-pentaene,
    • characterized substantially by at least one of the following powder x-ray diffraction pattern peaks expressed in term of 2Θ as measured with copper radiation chosen from: 6.1, 16.8 and 21.9.

III. The Accused Instrumentality

Product Identification

Plaintiff’s proposed Abbreviated New Drug Application (“ANDA”) No. 213019 product, which are varenicline tablets in 0.5 mg and 1 mg dosages (Compl. ¶2).

Functionality and Market Context

The product is a proposed generic version of Defendants’ smoking cessation drug, Chantix® (Compl. ¶2-3). As an ANDA product, it is intended to be bioequivalent to the reference listed drug (Compl. ¶18-19). The complaint alleges that a judicial determination of non-infringement or invalidity would enable Ajanta to bring its product to market at the earliest possible date (Compl. ¶7). The complaint does not provide sufficient detail for analysis of the specific salt form or crystalline structure of the varenicline in Ajanta's proposed product.

IV. Analysis of Infringement Allegations

The complaint is for a declaratory judgment of non-infringement and/or invalidity and therefore does not contain affirmative infringement allegations or a claim chart. Instead, it makes the conclusory assertion that Ajanta's proposed ANDA product will not infringe the patents-in-suit (Compl. ¶39). The analysis will therefore focus on the potential points of contention that would arise should Pfizer counterclaim for infringement.

No probative visual evidence provided in complaint.

  • Identified Points of Contention:
    • Scope Questions (’927 Patent): A potential dispute over the ’927 Patent could involve the scope of "tartrate salt." If Ajanta's product contains any tartrate salt form of varenicline, it would likely fall within the literal scope of claim 1. Consequently, the central dispute for this patent will foreseeably be over its validity, with Ajanta arguing the claimed subject matter is invalid under 35 U.S.C. §§ 101, 102, 103, and/or 112 (Compl. ¶50).
    • Technical Questions (’119 Patent): The primary infringement question for the ’119 Patent will be a factual one: does the specific crystalline form of varenicline L-tartrate in Ajanta’s proposed product exhibit at least one of the specific powder X-ray diffraction (PXRD) peaks recited in claim 1? This determination would require expert analysis of confidential data from Ajanta’s ANDA submission.
    • Technical Questions (Validity): A key validity question for both patents will be whether the claimed tartrate salts and their specific polymorphs were obvious improvements under 35 U.S.C. § 103. This may turn on whether a person of ordinary skill in the art would have been motivated to create tartrate salts of varenicline to solve known stability and hygroscopicity issues, and would have had a reasonable expectation of success in finding the specific, stable polymorphs claimed by Pfizer.

V. Key Claim Terms for Construction

  • Term: "tartrate salt" (’927 Patent, Claim 1)

    • Context and Importance: This term defines the entire scope of the broadest claim of the ’927 Patent. Its construction is fundamental to any infringement or validity analysis.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification explicitly lists multiple types of tartrate salts, including "the L-tartrate, D-tartrate, D,L-tartrate and meso-tartrate salts" ('927 Patent, col. 3:37-39). This language may support a construction that encompasses any of these salt forms.
      • Evidence for a Narrower Interpretation: The patent’s background emphasizes that the invention was driven by the need to find a salt with superior properties like low hygroscopicity ('927 Patent, col. 9:20-30). A party challenging the patent might argue that the term should be limited to only those tartrate salts that actually exhibit these superior, non-hygroscopic properties.

  • Term: "characterized substantially by" (’119 Patent, Claim 1)

    • Context and Importance: This phrase links the chemical compound to its analytical "fingerprint" (the PXRD peaks). The interpretation of "substantially" will determine how closely the accused product's PXRD pattern must match the pattern defined in the claims. Practitioners may focus on this term because it is a common source of dispute in pharmaceutical patent cases involving polymorphs.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The use of "substantially" suggests that an exact match is not required and that minor variations in peak position or the presence of other peaks do not necessarily avoid infringement. The patent's own description of PXRD data includes a margin of error (e.g., "Angle 2Θ (±0.2)"), which supports the notion that absolute precision is not intended ('119 Patent, col. 3:52-53).
      • Evidence for a Narrower Interpretation: A party could argue that "substantially" requires that the recited peaks be the most prominent or defining features of the diffraction pattern, not minor or incidental peaks. The patent distinguishes between multiple polymorphs (Forms A, B, and C) based on their distinct patterns, suggesting the recited peaks are essential for identification and not merely optional features ('119 Patent, Fig. 6).

VI. Other Allegations

This section is not applicable as the complaint is for declaratory judgment of non-infringement and invalidity, and does not contain allegations of indirect or willful infringement.

VII. Analyst’s Conclusion: Key Questions for the Case

  • A central question for the case will be one of validity: Were the claimed tartrate salt forms of varenicline, particularly the specific polymorphs identified in the ’119 Patent, non-obvious inventions under 35 U.S.C. § 103? The outcome may depend on whether a person skilled in the art would have been motivated to select tartaric acid from a range of possible salt-formers with a reasonable expectation of creating a uniquely stable and non-hygroscopic crystalline form.
  • Should Pfizer counterclaim for infringement, a key evidentiary question will be one of technical identity: Does the specific varenicline salt used in Ajanta’s proposed generic product have the same crystalline structure—as defined by the PXRD "fingerprints" recited in the ’119 Patent's claims—as Pfizer’s patented polymorph? This will require a direct comparison of confidential product data against the claim limitations.
  • A fundamental procedural issue shaping the litigation is Pfizer’s decision not to sue Ajanta within the 45-day statutory window. This has allowed Ajanta to initiate the lawsuit on its own terms as a declaratory judgment action, potentially influencing litigation strategy and timing.