DCT
1:24-cv-00953
Pfizer Inc. v. Ajanta Pharma Limited
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: Ajanta Pharma Limited (India)
- Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP; Arnold & Porter Kaye Scholer LLP; DLA Piper LLP (US)
- Case Identification: 1:24-cv-00953, D. Del., 08/16/2024
- Venue Allegations: Venue is alleged to be proper because the defendant is a foreign corporation, which may be sued in any judicial district.
- Core Dispute: Plaintiff alleges that Defendant's filing of an Abbreviated New Drug Application (ANDA) to market a generic version of Plaintiff's Xeljanz® XR product constitutes an act of infringement of a patent covering the active pharmaceutical ingredient.
- Technical Context: The technology involves a specific pyrrolo[2,3-d]pyrimidine compound, tofacitinib, which functions as a Janus kinase (JAK) inhibitor for treating various autoimmune diseases.
- Key Procedural History: This action was initiated under the Hatch-Waxman Act following Defendant’s submission of ANDA No. 219542 with a Paragraph IV certification. The certification alleges that U.S. Reissue Patent No. RE41,783 is invalid, unenforceable, and/or not infringed. The complaint notes that Defendant's detailed statement accompanying the certification alleges invalidity but does not contain a non-infringement argument. The patent-in-suit is a reissue of U.S. Patent No. 6,627,754, and its expiration date has been extended by the USPTO.
Case Timeline
| Date | Event |
|---|---|
| 1999-12-10 | RE'783 Patent Priority Date |
| 2003-09-30 | Original U.S. Patent No. 6,627,754 Issued |
| 2010-09-28 | U.S. Reissue Patent No. RE41,783 Issued |
| 2016-12-14 | USPTO Issues Notice extending RE'783 Patent expiration date |
| 2024-07-01 | Date of Ajanta's Notice Letter to Pfizer |
| 2024-08-16 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Reissue Patent No. RE41,783 - "Pyrrolo[2,3-d]pyrimidine Compounds,"
- Patent Identification: U.S. Reissue Patent No. RE41,783, "Pyrrolo[2,3-d]pyrimidine Compounds," issued September 28, 2010. (Compl. ¶22).
The Invention Explained
- Problem Addressed: The patent addresses the need for effective immunosuppressive agents to treat a range of conditions, including organ transplant rejection and autoimmune diseases such as rheumatoid arthritis and psoriasis (RE’783 Patent, col. 5:11-23). The background identifies the Janus Kinase 3 (JAK3) signaling pathway as a promising therapeutic target, as its expression is limited to hematopoietic cells, suggesting that its inhibition could provide immunosuppression with potentially fewer side effects than less specific agents (RE’783 Patent, col. 5:25-36).
- The Patented Solution: The invention provides a class of chemical compounds, specifically pyrrolo[2,3-d]pyrimidines, that are designed to inhibit protein kinases like JAK3 (RE’783 Patent, col. 5:11-15). By blocking the JAK3 pathway, these compounds modulate immune activity, which can be useful in treating T-cell proliferative disorders and other conditions where immunosuppression is desired (RE’783 Patent, col. 5:36-43). The patent discloses a core chemical structure (Formula I) and various substitutions to define the scope of the invented compounds (RE’783 Patent, col. 5:45-53).
- Technical Importance: The invention provided a targeted approach to immunosuppression by focusing on the JAK3 enzyme, which plays a critical role in the maturation and function of B and T lymphocytes (RE’783 Patent, col. 5:36-39).
Key Claims at a Glance
- The complaint asserts infringement of "at least claim 4" of the RE'783 patent (Compl. ¶36).
- Claim 4 is a dependent claim that recites a single, specific chemical compound: "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" (RE’783 Patent, col. 24:25-30). This compound is also described in the specification as Example 14 (RE’783 Patent, col. 19:33-37).
- This claim depends from independent claim 1, which defines the general chemical genus of pyrrolo[2,3-d]pyrimidine compounds.
III. The Accused Instrumentality
Product Identification
- Defendant Ajanta's proposed generic drug products, identified as "Ajanta Generic XR Tablets" and more specifically described as "Tofacitinib Extended Release Tablets, Eq 11 mg Base; Eq 22 mg Base" (Compl. ¶¶2, 29). These products are the subject of ANDA No. 219542 (Compl. ¶2).
Functionality and Market Context
- The accused products are generic copies of Pfizer's Xeljanz® XR (Compl. ¶2). The active ingredient in Xeljanz XR is tofacitinib citrate, which functions as an inhibitor of Janus kinases (JAKs) (Compl. ¶¶15, 17). It is formulated for once-daily administration and is approved for treating conditions such as rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis (Compl. ¶¶15, 18). The filing of the ANDA is alleged to be a statutory act of infringement under 35 U.S.C. § 271(e)(2)(A), intended to secure FDA approval to market these generic copies prior to the expiration of the RE'783 patent (Compl. ¶¶30, 36). No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
The complaint alleges that Ajanta's filing of its ANDA is a direct infringement of at least claim 4 of the RE'783 patent (Compl. ¶36). The infringement theory rests on the assertion that the active pharmaceutical ingredient in Ajanta's proposed generic product is the same chemical compound protected by claim 4.
RE'783 Patent Infringement Allegations
| Claim Element (from Claim 4) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| The compound 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. | Ajanta's ANDA No. 219542 seeks approval to market generic copies of Pfizer's Xeljanz® XR. The active ingredient in Xeljanz® XR is tofacitinib citrate, which is the citrate salt of the compound recited in claim 4. Ajanta's proposed product is described as containing tofacitinib. | ¶¶2, 15, 16, 29, 36 | col. 19:33-37; col. 24:25-30 |
- Identified Points of Contention:
- Scope Questions: The complaint states that Ajanta’s Paragraph IV certification was accompanied by a detailed statement that "does not contain a noninfringement argument with respect to the RE'783 patent" (Compl. ¶33). This suggests that the primary dispute may not be over infringement, but rather over the validity of the asserted claim.
- Technical Questions: The central factual question for infringement is whether the active pharmaceutical ingredient in Ajanta's ANDA product is, in fact, the chemical entity recited in claim 4. Given that Ajanta's product is a proposed generic of Xeljanz® XR and that Ajanta has apparently not raised a non-infringement defense, the analysis may focus less on claim scope and more on Ajanta's validity challenges.
V. Key Claim Terms for Construction
The complaint does not provide sufficient detail for analysis of specific claim terms for construction. As the asserted claim recites a single chemical compound, significant disputes over claim term meaning are less likely than in other technology areas. The infringement analysis will likely depend on a direct comparison of the chemical structure of Ajanta's active ingredient with the structure recited in claim 4. The term "pharmaceutically acceptable salt thereof" is standard in the art, and the complaint identifies the accused product's active ingredient as a citrate salt, which is a conventional salt form contemplated by the patent (RE'783 Patent, col. 6:7).
VI. Other Allegations
- Indirect Infringement: The complaint’s prayer for relief seeks to enjoin Ajanta from "inducing or contributing to" infringement (Compl. p. 8, ¶C). However, the body of the complaint does not plead specific facts to support the knowledge and intent elements required for a standalone claim of indirect infringement.
- Willful Infringement: The complaint does not contain an explicit allegation of willful infringement. It does allege that Ajanta had "knowledge of the RE’783 patent when it submitted ANDA No. 219542" (Compl. ¶37) and requests a finding that the case is "exceptional" under 35 U.S.C. § 285, which would entitle Pfizer to an award of attorneys' fees (Compl. p. 8, ¶D). These allegations lay the groundwork for a potential future argument regarding enhanced damages or fees.
VII. Analyst’s Conclusion: Key Questions for the Case
Based on the complaint, the litigation will likely center on the following questions:
- A foundational question of factual identity: Is the tofacitinib compound in Ajanta's ANDA product structurally identical to the compound recited in claim 4 of the RE'783 patent? The complaint's assertion that Ajanta has not offered a non-infringement argument suggests this may not be a point of significant dispute.
- A dispositive question of patent validity: The core of the case will likely be Ajanta’s challenge to the validity of claim 4. As infringement appears to be conceded for the sake of argument, the central issue for the court will be whether Ajanta can prove by clear and convincing evidence that the asserted claim is invalid on grounds such as obviousness, lack of enablement, or insufficient written description.