DCT

1:25-cv-00775

Pfizer Inc v. Apotex Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-00775, D. Del., 06/23/2025
  • Venue Allegations: Venue is asserted on the basis that Defendant Apotex 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) for a generic version of Plaintiff's Xeljanz® XR product constitutes an act of infringement of a patent covering the drug's active ingredient.
  • Technical Context: The technology relates to pyrrolo[2,3-d]pyrimidine compounds, specifically tofacitinib, which function as Janus Kinase (JAK) inhibitors for treating autoimmune diseases such as rheumatoid arthritis.
  • Key Procedural History: The patent-in-suit is a reissue of U.S. Patent No. 6,627,754. The U.S. Patent and Trademark Office granted a patent term extension, setting the expiration date to December 8, 2025. The lawsuit was triggered by Defendant’s notice letter, sent pursuant to the Hatch-Waxman Act, which included a Paragraph IV certification alleging the patent is invalid.

Case Timeline

Date Event
1999-12-10 Priority Date for RE41,783 Patent
2003-09-30 Issue Date of original U.S. Patent No. 6,627,754
2010-09-28 Issue Date of Reissue Patent No. RE41,783
2016-12-14 USPTO extends RE41,783 patent expiration date
2025-05-08 Apotex sends Notice Letter regarding ANDA filing to Pfizer
2025-06-23 Complaint Filed
2025-12-08 Extended Expiration Date of RE41,783 Patent

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

  • Patent Identification: 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 autoimmune diseases (RE’783 Patent, col. 5:11-24). Existing therapies can have significant side effects. The patent identifies the Janus Kinase 3 (JAK3) signaling pathway as a promising target for immunosuppression because its expression is largely limited to hematopoietic (blood-forming) cells, suggesting that a JAK3 inhibitor could have a more targeted effect (RE’783 Patent, col. 5:25-36).
    • The Patented Solution: The invention is a family of chemical compounds based on a pyrrolo[2,3-d]pyrimidine core structure that are designed to inhibit protein kinases, particularly JAK3 (RE’783 Patent, Abstract). By blocking the JAK3 pathway, these compounds are intended to modulate the immune system's activity, making them useful for treating T-cell proliferative disorders like transplant rejection and various autoimmune conditions (RE’783 Patent, col. 5:36-42).
    • Technical Importance: The invention provided a novel mechanism for immunosuppression by targeting a specific enzyme (JAK3) critical for the function and maturation of lymphocytes (immune cells), offering a potential therapeutic advantage over less specific agents (RE’783 Patent, col. 5:36-42).
  • Key Claims at a Glance:
    • The complaint asserts infringement of "at least claim 4" (Compl. ¶36). Claim 4 is a dependent claim that specifies a single chemical compound. It depends from independent claim 1.
    • Independent Claim 1:
      • A compound of a specified formula I, or a pharmaceutically acceptable salt thereof.
      • The formula has a core pyrrolo[2,3-d]pyrimidine structure with three substitution points: R¹, R², and R³.
      • R¹ is defined as a group with a piperidinyl ring (R⁵) attached via an optional linker.
      • The R⁵ piperidinyl ring is itself substituted with one of a large Markush group of chemical moieties.
      • R² and R³ are both defined as hydrogen.
    • The complaint does not explicitly reserve the right to assert other claims but uses the language "at least claim 4" (Compl. ¶36, ¶38, ¶39).

III. The Accused Instrumentality

  • Product Identification: The accused products are Apotex’s proposed "Apotex Generic Tofacitinib XR Tablets" in 11 mg and 22 mg extended-release formulations (Compl. ¶2, ¶29).
  • Functionality and Market Context:
    • The complaint alleges these are generic copies of Pfizer's Xeljanz® XR product (Compl. ¶2). The active ingredient in Xeljanz XR is tofacitinib citrate, which is an inhibitor of Janus kinases (JAKs) (Compl. ¶15, ¶17).
    • The products are intended for the same indications as Xeljanz XR, including the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis (Compl. ¶17-18). The infringement alleged is the statutory act of filing Abbreviated New Drug Application (ANDA) No. 220458 with the U.S. Food and Drug Administration (FDA) to obtain approval to market these generic products prior to the expiration of the RE’783 patent (Compl. ¶2, ¶36).
    • No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not provide a detailed, element-by-element infringement analysis or an appended claim chart. The infringement theory is based on the statutory act of filing an ANDA under 35 U.S.C. § 271(e)(2). The complaint alleges that Apotex filed ANDA No. 220458 seeking approval to market a generic drug containing tofacitinib citrate (Compl. ¶2, ¶15). It further alleges this is an act of infringement of at least claim 4 of the RE’783 patent, which claims the compound tofacitinib (as 3-{4-Methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile) or its pharmaceutically acceptable salts (Compl. ¶36; RE’783 Patent, cl. 4). The complaint notes that Apotex’s notice letter to Pfizer did not contain a noninfringement argument, suggesting Apotex does not dispute that its product falls within the literal scope of claim 4 (Compl. ¶33).

  • Identified Points of Contention:
    • Technical Questions: The primary factual question, which appears to be undisputed by Apotex, is whether the active pharmaceutical ingredient in the "Apotex Generic Tofacitinib XR Tablets" is the specific compound recited in claim 4 of the RE’783 patent.
    • Scope Questions: A potential legal question, though not raised as a dispute in the complaint, is whether the tofacitinib citrate salt form in the accused product (Compl. ¶15) qualifies as a "pharmaceutically acceptable salt" of the base compound recited in claim 4, as required by the preamble of claim 1.

V. Key Claim Terms for Construction

The complaint does not indicate any immediate claim construction disputes, particularly since Apotex’s Paragraph IV certification is allegedly based on invalidity rather than noninfringement (Compl. ¶31, ¶33). However, should validity be litigated, the construction of terms in the independent claim from which claim 4 depends could become relevant to arguments about the scope of the prior art or the patent's enablement.

  • The Term: "a pharmaceutically acceptable salt thereof" (RE’783 Patent, cl. 1)
  • Context and Importance: This term is critical because the accused product is formulated with tofacitinib citrate, a salt, while the dependent claim specifies the base compound structure (Compl. ¶15-16; RE’783 Patent, cl. 4). The infringement case hinges on the accused salt form falling within the scope of a "pharmaceutically acceptable salt." Practitioners may focus on this term to confirm the scope of infringement, although it appears to be a standard term in pharmaceutical patents.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification provides a non-exhaustive list of acids that can be used to form such salts, including "citrate, acid citrate," among many others (RE’783 Patent, col. 4:5-11). This language suggests an intent to cover a wide range of conventional salt forms.
    • Evidence for a Narrower Interpretation: The patent does not appear to contain explicit language that would support a narrow interpretation excluding common forms like citrate. An argument for a narrower scope would likely need to rely on extrinsic evidence or arguments about what a person of ordinary skill in the art would have understood the term to mean at the time of the invention.

VI. Other Allegations

  • Indirect Infringement: The prayer for relief seeks to enjoin Apotex from "inducing or contributing to any of the foregoing" infringing acts (Compl., Prayer ¶C). However, the factual allegations in the body of the complaint focus on direct infringement under 35 U.S.C. § 271(a) and the artificial act of infringement under § 271(e)(2), without pleading specific facts to support knowledge and intent for inducement (Compl. ¶36, ¶38).
  • Willful Infringement: The complaint does not contain an explicit allegation of willful infringement or a request for enhanced damages. It does allege that Apotex had knowledge of the RE’783 patent when it submitted its ANDA (Compl. ¶37) and requests a finding that the case is "exceptional" under 35 U.S.C. § 285 for the purpose of recovering attorneys' fees (Compl., Prayer ¶D).

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

Based on the complaint, the dispute appears to be a classic Hatch-Waxman Act case where the central battleground will be patent validity, not infringement.

  1. A core issue will be one of patent validity: can Apotex prove, by clear and convincing evidence, that claim 4 of the RE’783 patent is invalid, as it certified to the FDA? The complaint states that Apotex’s notice letter asserted invalidity as the basis for its Paragraph IV certification (Compl. ¶31, ¶33).
  2. An antecedent question is one of literal infringement: does Apotex’s proposed generic product, which contains tofacitinib citrate, fall within the scope of claim 4, which covers a specific base compound or its "pharmaceutically acceptable salt"? The lack of a noninfringement argument from Apotex, as alleged in the complaint, suggests this may not be a contested issue (Compl. ¶33).
  3. The ultimate question for the court is one of remedy and timing: should the court order, pursuant to 35 U.S.C. § 271(e)(4)(A), that the effective date of any FDA approval for Apotex’s ANDA be no earlier than December 8, 2025, the expiration date of the RE’783 patent?