Pfizer Inc v. Annora Pharma Pvt Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Pfizer Inc. (Delaware), C.P. Pharmaceuticals International C.V. (Netherlands), PF Prism CV. (Netherlands), PBG Puerto Rico LLC (Puerto Rico), and PF Prism Imb BV. (Netherlands)
  • Defendant: Annora Pharma Private Limited (India) and Hetero USA, Inc. (Delaware)
  • Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP; Arnold & Porter Kaye Scholer LLP; DLA Piper LLP (US)
• Case Identification: 1:23-cv-00634, D. Del., 06/09/2023
• Venue Allegations: Venue is alleged to be proper in Delaware because Defendant Hetero USA, Inc. is a Delaware corporation and because, upon FDA approval, the accused generic product is expected to be marketed, distributed, and used in Delaware.
• Core Dispute: Plaintiff alleges that Defendants' filing of an Abbreviated New Drug Application (ANDA) to market a generic version of Plaintiff's Xeljanz® (tofacitinib) oral solution constitutes an act of infringement of a patent covering the tofacitinib compound.
• Technical Context: The technology involves pyrrolo[2,3-d]pyrimidine compounds, which function as Janus kinase (JAK) inhibitors to provide immunosuppression for treating various autoimmune diseases.
• Key Procedural History: The action was triggered by Defendants' submission of ANDA No. 218123 with a "Paragraph IV" certification, asserting that U.S. Reissue Patent No. RE41,783 is invalid or will not be infringed. The patent-in-suit is a reissue of an earlier patent and is listed in the FDA's "Orange Book" as covering the Xeljanz® product. The patent's expiration date was extended by the USPTO until December 8, 2025.

Case Timeline

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

U.S. Reissue Patent No. RE41,783, Pyrrolo[2,3-d]pyrimidine Compounds, issued September 28, 2010

The Invention Explained

• Problem Addressed: The patent describes a need for effective immunosuppressive agents to treat organ transplant rejection and various autoimmune diseases, such as rheumatoid arthritis (RE’783 Patent, col. 1:12-23). The background identifies the Janus Kinase 3 (JAK3) signaling pathway as a promising therapeutic target, noting that its expression is limited to hematopoietic cells, which suggests that inhibiting JAK3 could suppress immune response with potentially fewer systemic side effects than broader-acting agents (RE’783 Patent, col. 1:26-36).
• The Patented Solution: The invention discloses a class of chemical compounds, known as pyrrolo[2,3-d]pyrimidines, that are designed to inhibit protein kinases, specifically JAK3 (RE’783 Patent, col. 1:12-17). The patent provides the general chemical structure and specific examples of these compounds, which are asserted to be useful as immunosuppressive agents (RE’783 Patent, Abstract; col. 1:44-54).
• Technical Importance: The invention provided a targeted mechanism for immunosuppression by focusing on the JAK3 pathway, which plays a critical role in the maturation and function of T and B lymphocytes, key mediators of the immune response involved in transplant rejection and autoimmune disorders (RE’783 Patent, col. 1:36-42).

Key Claims at a Glance

• The complaint asserts infringement of at least independent claim 4 (Compl. ¶38).
• Claim 4 recites a single chemical compound or its salt: "3-{4-Methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile, or a pharmaceutically acceptable salt thereof."

III. The Accused Instrumentality

• Product Identification: The accused instrumentality is "Annora Tofacitinib Oral Solution," the proposed generic drug product described in Defendants' Abbreviated New Drug Application (ANDA) No. 218123 (Compl. ¶2).
• Functionality and Market Context: The complaint alleges that Annora's product is a "generic copy of Pfizer's Xeljanz® (tofacitinib) oral solution (1 mg/mL)" (Compl. ¶2, ¶30). Xeljanz is a Janus kinase (JAK) inhibitor approved for treating conditions including rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis (Compl. ¶20). Defendants seek FDA approval to market their generic version prior to the expiration of the RE'783 patent (Compl. ¶2).

No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not contain a formal claim chart. The infringement theory is statutory, based on the act of filing an ANDA under 35 U.S.C. § 271(e)(2)(A), which seeks approval to market a drug claimed in a patent before its expiration (Compl. ¶38). The core of the infringement allegation is that the active ingredient in Annora's proposed product is the same chemical compound recited in claim 4.

RE’783 Patent Infringement Allegations

• Identified Points of Contention:
  • Scope Questions: The primary question for infringement is one of identity: is the compound in Annora's ANDA product the same as, or a salt of, the compound recited in claim 4? The complaint notes that Annora's pre-suit "Detailed Statement does not contain a noninfringement argument" (Compl. ¶34), which suggests that infringement may not be the central dispute.
  • Technical Questions: The key factual question for the court will be to confirm the chemical structure of the active pharmaceutical ingredient in the "Annora Tofacitinib Oral Solution." In ANDA litigation, this is typically established through the specifications and data submitted to the FDA in the ANDA itself.

V. Key Claim Terms for Construction

In a case involving a claim to a single, specific chemical compound, claim construction disputes are less common than in cases involving apparatuses or complex methods. The primary "term" for construction is the chemical name itself.

• The Term: "3-{4-Methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile"
• Context and Importance: The definition of this term is dispositive for infringement. Practitioners may focus on this term only if there is an ambiguity in the chemical nomenclature. However, given that this name corresponds to the well-known compound tofacitinib, and the accused product is a generic version of a tofacitinib product, a significant dispute over the term's meaning is not anticipated based on the complaint.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language "or a pharmaceutically acceptable salt thereof" provides explicit scope beyond the base compound to include various salt forms, such as the citrate salt found in Pfizer's Xeljanz®.
  • Evidence for a Narrower Interpretation: The patent specification provides a precise and unambiguous definition of the core compound by detailing its synthesis and characterization in "Example 14" (RE’783 Patent, col. 19:35-40). This example serves to fix the exact chemical structure, leaving little room for interpretation beyond the recited structure itself.

VI. Other Allegations

• Indirect Infringement: The complaint alleges that Defendant Hetero USA, Inc. induced infringement by "actively and knowingly causing to be submitted and/or assisted with, participating in, contributing to, and/or directing the submission" of Annora Pharma's ANDA to the FDA (Compl. ¶44). The complaint alleges Hetero USA acted with knowledge of the RE'783 patent (Compl. ¶44).
• Willful Infringement: The complaint does not contain an explicit allegation of willful infringement. However, it requests a judgment that the case is "exceptional" under 35 U.S.C. § 285, which would entitle Pfizer to an award of attorneys' fees (Compl., Prayer for Relief ¶E). This request is supported by the allegation that Annora had knowledge of the RE'783 patent when it submitted its ANDA (Compl. ¶39).

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

The complaint foreshadows that the central legal battle will concern the validity of the patent-in-suit rather than infringement. The key questions for the court are therefore likely to be:

1. A threshold question of infringement by identity: Will the evidence confirm that the active pharmaceutical ingredient in Annora's proposed generic product is, in fact, the chemical compound recited in claim 4 of the RE'783 patent or a pharmaceutically acceptable salt thereof? Based on the complaint, this issue may not be in dispute.
2. The central question of patent validity: As the complaint states that Annora's Paragraph IV certification is based on allegations of invalidity and unenforceability (Compl. ¶32, ¶34), the case will likely turn on whether Defendants can prove by clear and convincing evidence that claim 4 of the RE'783 patent is invalid. The potential grounds for such a challenge (e.g., anticipation, obviousness, lack of enablement) will form the core of the litigation.