DCT

1:22-cv-01501

Pfizer Inc v. Sun Pharmaceutical Industries Ltd

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Key Events
Complaint
complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:22-cv-01501, D. Del., 11/16/2022
  • Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendant Sun Pharmaceutical Industries, Inc. is a Delaware corporation and because Defendants are alleged to manufacture, market, and sell generic drugs for distribution in Delaware.
  • Core Dispute: Plaintiff alleges that Defendant’s filing of an Abbreviated New Drug Application (ANDA) to market generic versions of Plaintiff's Xeljanz® XR product 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 for the treatment of autoimmune diseases such as rheumatoid arthritis and ulcerative colitis.
  • Key Procedural History: This action was initiated under the Hatch-Waxman Act following Plaintiff's receipt of Paragraph IV notice letters from Defendant, dated May 31, 2022, and October 3, 2022, asserting that the patent-in-suit is invalid, unenforceable, and/or will not be infringed by Defendant's proposed generic product. The patent-in-suit 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 '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 extends expiration date of '783 Patent
2022-05-31 Sun sends Paragraph IV Notice Letter for 11 mg tablets
2022-10-03 Sun sends Paragraph IV Notice Letter for 22 mg tablets
2022-11-16 Complaint Filed

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.

The Invention Explained

  • Problem Addressed: The patent describes a need for immunosuppressive agents to treat a range of conditions, including organ transplant rejection and various autoimmune diseases. ('783 Patent, col. 1:12-24). The patent identifies Janus Kinase 3 (JAK3) as a promising therapeutic target because its expression is limited to hematopoietic cells and it is essential for the maturation and function of B and T lymphocytes, which are central to the immune response. ('783 Patent, col. 1:28-36).
  • The Patented Solution: The invention provides a class of chemical compounds based on a pyrrolo[2,3-d]pyrimidine structure, which are designed to inhibit protein kinases, and specifically JAK3. ('783 Patent, Abstract; col. 1:43-48). By blocking the JAK3 signaling pathway, these compounds are intended to achieve immunosuppression and thereby treat the identified diseases. ('783 Patent, col. 1:36-42).
  • Technical Importance: This approach represented a targeted mechanism for modulating immune activity, potentially offering a new therapeutic option for T-cell proliferative disorders and autoimmune diseases by focusing on the specific JAK3 enzyme pathway. ('783 Patent, col. 1:36-42).

Key Claims at a Glance

  • The complaint asserts infringement of at least independent claim 1. (Compl. ¶46).
  • Independent Claim 1 defines a genus of compounds having:
    • A core pyrrolo[2,3-d]pyrimidine structure.
    • An R¹ substituent group which is, or contains, a substituted piperidinyl ring.
    • Hydrogen atoms at the R² and R³ positions of the pyrrolo[2,3-d]pyrimidine core.
    • The claim also covers pharmaceutically acceptable salts of these compounds.
  • The complaint notes that Defendant’s non-infringement contentions address claims 1-3 but not dependent claim 4, which recites the specific compound 3-{4-Methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile, known as tofacitinib. (Compl. ¶36, ¶42; ’783 Patent, col. 24:25-30).

III. The Accused Instrumentality

Product Identification

  • Defendant’s proposed "Sun Generic 11 mg XR Tablets" and "Sun Generic 22 mg XR Tablets," which are the subject of ANDA No. 209790. (Compl. ¶2).

Functionality and Market Context

  • The accused products are extended-release tablets for oral use containing tofacitinib citrate. (Compl. ¶32, ¶38). Tofacitinib citrate is the active ingredient in Plaintiff's Xeljanz® XR product and functions as a JAK inhibitor. (Compl. ¶18, ¶20).
  • The complaint alleges these products are generic copies of Plaintiff’s Xeljanz® XR and are intended for the same therapeutic uses, such as the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis. (Compl. ¶2, ¶20-21).

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

RE41,783 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A compound of the formula I... or a pharmaceutically acceptable salt thereof The complaint alleges that Defendant's ANDA seeks approval to market a product containing tofacitinib citrate, which is a pharmaceutically acceptable salt of a compound alleged to fall within the scope of Formula I. ¶2, ¶19, ¶46 col. 1:43-48
wherein R¹ is a group of the formula... [defining a substituted piperidinyl-containing structure] The infringement theory is that the chemical structure of tofacitinib, which contains a substituted piperidinyl group attached to a pyrrolo[2,3-d]pyrimidine core, meets the structural requirements for the R¹ substituent as defined in the claim. ¶19, ¶48 col. 21:8-52
and R² and R³ are each hydrogen The chemical structure of tofacitinib, (3R,4R)-4-methyl-3-(methyl-7H-pyrrolo [2,3-d] pyrimidin-4-ylamino)-ß-oxo-1-piperidinepropanenitrile, has hydrogen atoms at the positions corresponding to R² and R³ on the pyrrolo[2,3-d]pyrimidine ring, as required by the claim. ¶19 col. 22:35-36
  • Identified Points of Contention:
    • Scope Questions: A central question will be whether the specific chemical structure of tofacitinib, including its stereochemistry as described in the complaint, falls within the genus of compounds defined by the limitations of independent claim 1. While claim 4 recites tofacitinib specifically, the dispute over the broader genus claim 1 will require a detailed structural comparison.
    • Technical Questions: The primary technical question for the court will be whether the evidence from Defendant's ANDA filing confirms that its active pharmaceutical ingredient has the precise chemical structure and salt form covered by the asserted claim(s).

V. Key Claim Terms for Construction

  • The Term: "pharmaceutically acceptable salt thereof"

    • Context and Importance: This term is critical because both the branded and proposed generic products are citrate salts of the tofacitinib compound. (Compl. ¶19, ¶32). While the parties appear to agree on the salt form, the construction of this term defines the outer boundary of protection beyond the base compound and is fundamental in nearly all small-molecule pharmaceutical patent cases.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification provides a non-exhaustive list of potential acid addition salts, including "citrate, acid citrate, tartrate," among many others, suggesting the term is meant to be encompassing. ('783 Patent, col. 4:5-12).
      • Evidence for a Narrower Interpretation: A party could argue that the term is limited to salts that do not materially alter the properties of the parent compound, though the specification provides little basis for such a narrow reading.

  • The Term: "piperidinyl substituted by..."

    • Context and Importance: This phrase appears in the definition of the R⁵ group within Claim 1 and is central to defining the structure of the R¹ substituent. ('783 Patent, col. 21:35). The specific structure of tofacitinib includes a substituted piperidinyl ring, so whether that specific substitution pattern is covered by the claim's language is a core infringement question.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: Claim 1 provides a long list of permissible substituent groups for the piperidinyl ring, including "cyano," "alkyl," and groups that can form an "oxo" substituent, suggesting broad coverage. ('783 Patent, col. 21:35-52).
      • Evidence for a Narrower Interpretation: A defendant might point to the specific examples and preferred embodiments in the specification (e.g., the named compounds in col. 7-8 and col. 24) to argue that the term should be understood in the context of those specific structures, potentially limiting its scope.

VI. Other Allegations

  • Indirect Infringement: The complaint does not contain allegations of indirect infringement.
  • Willful Infringement: The complaint does not include a formal count for willful infringement. However, it alleges that Defendant had knowledge of the '783 patent when it submitted its ANDA. (Compl. ¶47). This allegation, coupled with a prayer for relief seeking attorneys' fees for an "exceptional case" under 35 U.S.C. § 285, suggests a potential future argument related to culpable conduct. (Compl. Prayer for Relief ¶D).

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

  • A core issue will be one of structural scope: Does the specific chemical compound tofacitinib, as it will be formulated in Defendant's generic product, meet every structural limitation of the chemical genus defined in independent claim 1 of the '783 patent?
  • A key evidentiary question will be one of ANDA confirmation: What will the chemical analysis contained within Defendant’s ANDA No. 209790 reveal about the precise structure, stereochemistry, and salt form of its proposed active pharmaceutical ingredient, and will that evidence definitively place it within the scope of the asserted patent claim(s)?