DCT

1:19-cv-00517

Pfizer Inc v. Ajanta Pharma Ltd

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:19-cv-00517, D. Del., 03/15/2019
  • Venue Allegations: Defendants have consented to venue in the District of Delaware for the purposes of this action.
  • Core Dispute: Plaintiff alleges that Defendant's submission of an Abbreviated New Drug Application (ANDA) to market a generic version of Plaintiff's Xeljanz® (tofacitinib) tablets constitutes an act of patent infringement.
  • Technical Context: The technology concerns pharmaceutical compositions, specifically a compound (tofacitinib) that functions as a Janus kinase (JAK) inhibitor for treating autoimmune diseases, and a specific crystalline salt form of that compound.
  • Key Procedural History: This is a Hatch-Waxman action initiated after Ajanta filed an ANDA with a Paragraph IV certification, asserting that Pfizer's patents listed in the FDA's Orange Book are invalid, unenforceable, or will not be infringed by Ajanta's proposed generic product. The complaint alleges that Ajanta's detailed statement accompanying its certification raises arguments for invalidity but not for non-infringement. U.S. Reissue Patent No. RE41,783 is a reissue of U.S. Patent No. 6,627,754 and its expiration date was extended by the USPTO.

Case Timeline

Date Event
1999-12-10 RE’783 Patent Priority Date
2001-12-06 ’027 Patent Priority Date
2003-09-30 Original U.S. Patent No. 6,627,754 Issued
2005-11-15 ’027 Patent Issued
2010-09-28 RE’783 Patent Issued
2016-12-14 USPTO Extends Expiration Date of RE’783 Patent
2019-02-04 Ajanta Sends Paragraph IV Notice Letter to Pfizer
2019-03-15 Complaint Filed

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

U.S. Patent No. 6,965,027 - "Crystalline 3-{4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile citrate," Issued Nov. 15, 2005

The Invention Explained

  • Problem Addressed: The patent addresses the need for a solid form of the active pharmaceutical ingredient tofacitinib citrate with physical properties suitable for formulation into a stable drug product. The patent states that the claimed crystalline form has "solid state properties which are acceptable to support tablet development" (’027 Patent, col. 2:53-57).
  • The Patented Solution: The invention is a specific, novel crystalline form of tofacitinib mono citrate salt. This crystalline form, or polymorph, is defined by its unique physical characteristics, including a distinct X-ray powder diffraction (XRPD) pattern and a specific melting temperature range, which ensure consistent properties for manufacturing and therapeutic use (’027 Patent, Abstract; col. 2:6-14; FIG. 1).
  • Technical Importance: In pharmaceutical science, the specific crystalline form of a drug is critical, as it can affect the drug's stability, dissolution rate, bioavailability, and manufacturability.

Key Claims at a Glance

  • The complaint asserts infringement of at least independent claim 1 (Compl. ¶40).
  • Claim 1 recites:
    • A crystalline form of 3-{(3R,4R)-4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile mono citrate salt.
  • The complaint does not explicitly reserve the right to assert dependent claims, but alleges infringement of "one or more claims" (Compl. ¶38).

U.S. Reissue Patent No. RE41,783 - "Pyrrolo[2,3-D]pyrimidine Compounds," Issued Sep. 28, 2010

The Invention Explained

  • Problem Addressed: The patent identifies a need for effective immunosuppressive agents for treating conditions such as organ transplant rejection, rheumatoid arthritis, psoriasis, and other autoimmune diseases (RE’783 Patent, col. 1:11-23).
  • The Patented Solution: The invention provides a class of chemical compounds, known as pyrrolo[2,3-d]pyrimidines, that function as inhibitors of the Janus Kinase 3 (JAK3) enzyme. Because JAK3 expression is primarily limited to immune cells, inhibiting this enzyme offers a targeted way to modulate immune activity and treat associated disorders (RE’783 Patent, col. 1:24-43). Tofacitinib, the active ingredient in Xeljanz®, is a compound within this patented class.
  • Technical Importance: The development of JAK inhibitors represented a significant advance in treating autoimmune diseases, providing a novel, targeted oral therapy as an alternative to broader immunosuppressants or injectable biologics.

Key Claims at a Glance

  • The complaint asserts infringement of at least independent claim 1 (Compl. ¶46).
  • Claim 1 recites a compound of a general Markush formula, the key elements of which cover tofacitinib:
    • A compound having a pyrrolo[2,3-d]pyrimidine core structure, or a pharmaceutically acceptable salt thereof.
    • Wherein the 4-position of the core is substituted with an R¹ group comprising a methyl-amino-piperidinyl moiety.
    • Wherein the R¹ group has a specific stereochemistry and is further substituted.
    • Wherein the R² and R³ substituents on the pyrrolo ring are both hydrogen.
  • The complaint alleges infringement of "one or more claims" of the patent (Compl. ¶44).

III. The Accused Instrumentality

  • Product Identification: The accused instrumentality is "Ajanta Generic Tablets," a proposed generic version of Pfizer’s Xeljanz® 5 mg tablets (Compl. ¶2).
  • Functionality and Market Context: The proposed Ajanta product contains tofacitinib citrate as its active ingredient in an amount equivalent to 5 mg of tofacitinib base (Compl. ¶¶ 14, 31). It is intended to be a generic substitute for Xeljanz®, which is a Janus kinase (JAK) inhibitor indicated for treating autoimmune conditions including rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis (Compl. ¶13). The filing of the ANDA itself signifies a commercial intent to enter the market upon FDA approval (Compl. ¶29).

IV. Analysis of Infringement Allegations

The complaint does not provide element-by-element allegations or a claim chart to detail its infringement theory. The infringement counts are pleaded at a high level.

  • ’027 Patent Infringement Allegations: The complaint alleges that Ajanta’s submission of its ANDA is a statutory act of infringement under 35 U.S.C. § 271(e)(2)(A) (Compl. ¶38). The substantive basis for the infringement claim is that Ajanta's proposed generic tablets will contain tofacitinib citrate and, upon information and belief, will be manufactured, used, or sold in a manner that infringes at least claim 1 of the ’027 Patent (Compl. ¶¶ 40-41). The core of this allegation is that the active ingredient in Ajanta's product will possess the specific crystalline structure claimed in the ’027 Patent.
  • RE’783 Patent Infringement Allegations: The complaint makes a parallel allegation for the RE’783 Patent, stating the ANDA submission is an act of infringement (Compl. ¶44). The theory is that the tofacitinib active ingredient contained within the Ajanta Generic Tablets is a chemical compound that falls within the scope of the genus of compounds recited in at least claim 1 of the RE’783 Patent (Compl. ¶¶ 46-47).
  • Identified Points of Contention:
    • Technical/Factual Question (’027 Patent): A primary issue for the ’027 Patent will be one of polymorphic identity. The key factual question is whether the tofacitinib citrate in Ajanta's proposed product is, in fact, the specific crystalline form defined by the patent's claims. This is an evidentiary question that will likely be resolved through scientific analysis of Ajanta's product samples.
    • Legal/Strategic Question (Both Patents): The complaint states that Ajanta's detailed statement accompanying its Paragraph IV certification "does not contain a noninfringement argument... other than that all claims are invalid" (Compl. ¶34). This raises the strategic question of whether Ajanta will contest infringement or focus its defense entirely on proving the asserted patent claims are invalid.

No probative visual evidence provided in complaint.

V. Key Claim Terms for Construction

  • Term from ’027 Patent: "crystalline form"

    • Context and Importance: This term is the foundation of claim 1 of the ’027 patent. Infringement hinges entirely on whether Ajanta's product is a "crystalline form" of the specified salt, as opposed to an amorphous form or a different crystalline polymorph. Practitioners may focus on this term because the patent’s own specification provides data to define what "the" novel crystalline form is.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The term "crystalline form" is not explicitly defined, which could support an argument for its plain and ordinary meaning in chemistry—any solid form exhibiting a regular, repeating atomic structure. The doctrine of claim differentiation may be invoked, as dependent claim 2 recites specific XRPD peaks, suggesting that independent claim 1 is not limited to only a form exhibiting those exact peaks.
      • Evidence for a Narrower Interpretation: The specification repeatedly refers to "the" novel crystalline form and characterizes it with specific data, including an XRPD pattern with "characteristic peaks expressed in degrees 2-theta (2θ) at 5.7, 16.1, 20.2 and 20.5" and a specific melting point range (’027 Patent, col. 2:6-14). A party could argue that the specification defines the claimed "crystalline form" as only the polymorph exhibiting these properties.

  • Term from RE’783 Patent: "a piperidinyl substituted by one to five..."

    • Context and Importance: This phrase appears in the definition of the R⁵ group in claim 1 and defines the scope of permissible modifications to the piperidinyl ring, which is a core part of the tofacitinib molecule (RE’783 Patent, col. 21:37). The construction of this term and the extensive list of possible substituents that follows will determine the precise boundaries of the chemical genus covered by the claim.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The claim uses the open-ended language "substituted by," followed by a long Markush list of chemical groups, suggesting any combination of one to five of these groups is covered.
      • Evidence for a Narrower Interpretation: The patent provides numerous specific working examples (e.g., Examples 1-26) of compounds that fall within the invention (RE’783 Patent, col. 17-20). A party could argue these examples implicitly limit the scope of what types of substitutions were contemplated and enabled by the inventors, potentially narrowing the interpretation of the substituent list.

VI. Other Allegations

  • Indirect Infringement: The complaint includes a prayer for relief seeking to enjoin Ajanta from "inducing or contributing to" infringement, which is a claim for indirect infringement (Prayer for Relief ¶C). The factual basis alleged is that Ajanta, upon approval, will market and distribute its generic tablets throughout the U.S. for uses covered by the patents (Compl. ¶36).
  • Willful Infringement: The complaint alleges that Ajanta had knowledge of the ’027 and RE’783 patents at the time it submitted its ANDA (Compl. ¶¶ 39, 45). This allegation of pre-suit knowledge, supported by Ajanta's statutorily required Paragraph IV certification against the Orange Book-listed patents, forms the basis for a potential willfulness claim. Plaintiff also seeks a judgment that this is an "exceptional case" under 35 U.S.C. § 285, which would entitle it to attorneys' fees (Prayer for Relief ¶D).

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

  1. A central issue will be a factual question of polymorphic identity: Does the active ingredient in Ajanta's proposed generic product exist in the specific crystalline form claimed by the ’027 patent, or does it utilize an alternative amorphous or polymorphic form that would place it outside the claim's scope?
  2. A key strategic question will be the focus of the dispute: Given the complaint's allegation that Ajanta's pre-suit notice letter focused exclusively on invalidity, the case may turn on whether Ajanta will mount a defense of non-infringement or concede that its product is covered by the claims and argue instead that the asserted claims of the ’027 and RE’783 patents are invalid.