DCT
1:24-cv-01427
Pfizer Inc v. Alkem Laboratories Ltd
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Pfizer Inc. (and related entities) (Delaware)
- Defendant: Alkem Laboratories Limited (India)
- Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP
- Case Identification: 1:24-cv-01427, D. Del., 12/30/2024
- Venue Allegations: Venue is asserted on the basis that the defendant is a foreign corporation, which may be sued in any judicial district.
- Core Dispute: Plaintiff alleges that Defendant’s submission of an Abbreviated New Drug Application (ANDA) to market a generic version of the drug Xeljanz® (tofacitinib) constitutes an act of infringement of a patent covering the tofacitinib molecule itself.
- Technical Context: The technology lies in the field of small-molecule kinase inhibitors, specifically compounds that inhibit Janus Kinase 3 (JAK3), for use as immunosuppressive agents in treating autoimmune conditions such as rheumatoid arthritis.
- Key Procedural History: The patent-in-suit is a reissue patent whose expiration date was extended by the USPTO. This lawsuit was statutorily triggered under the Hatch-Waxman Act by Defendant's filing of an ANDA with a Paragraph IV certification, which, according to the complaint, challenges the patent's validity but does not advance a non-infringement position.
Case Timeline
| Date | Event |
|---|---|
| 1999-12-10 | '783 Patent Priority Date |
| 2003-09-30 | Original U.S. Patent No. 6,627,754 Issue Date |
| 2010-09-28 | U.S. Reissue Patent No. RE41,783 Issue Date |
| 2016-12-14 | USPTO extends '783 Patent expiration date |
| 2024-11-15 | Date of Alkem's Notice Letter regarding its ANDA filing |
| 2024-12-30 | Complaint Filing Date |
| 2025-12-08 | '783 Patent Expiration Date listed in the FDA's Orange Book |
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 effective immunosuppressive agents for treating organ transplant rejection and a variety of autoimmune diseases, including rheumatoid arthritis, psoriasis, and lupus (’783 Patent, col. 5:16-24). The background identifies the Janus Kinase 3 (JAK3) enzyme as a critical component in the signaling pathways that lead to lymphocyte maturation and function, making it an attractive target for therapeutic intervention (’783 Patent, col. 5:36-42).
- The Patented Solution: The invention discloses a class of compounds, based on a pyrrolo[2,3-d]pyrimidine chemical scaffold, that are designed to inhibit the JAK3 enzyme (’783 Patent, col. 5:12-16). By blocking JAK3, these compounds are intended to modulate immune activity and thereby treat the underlying causes of various T-cell proliferative disorders (’783 Patent, col. 5:39-42; Abstract).
- Technical Importance: This approach represented a targeted mechanism for immunosuppression by focusing on JAK3, an enzyme whose expression is largely limited to hematopoietic cells, suggesting a potential for more specific immune modulation (’783 Patent, col. 5:27-30).
Key Claims at a Glance
- The complaint specifically asserts infringement of claim 4, which is dependent on independent claim 3.
- Independent Claim 3: Claims a compound selected from a list of specifically named chemical compounds, including:
- 3-{4-Methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile
- Asserted Dependent Claim 4: Narrows the invention to a single compound from the list in Claim 3:
- "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."
- The complaint reserves the right to assert additional claims (Compl. ¶35).
III. The Accused Instrumentality
Product Identification
- Product Identification: "Alkem Generic Tofacitinib Tablets," in 5 mg and 10 mg dosages, as described in Alkem's ANDA No. 219885 (Compl. ¶2, ¶27).
Functionality and Market Context
- Functionality and Market Context: The accused product is a proposed generic version of Pfizer's Xeljanz®, with tofacitinib citrate as the active pharmaceutical ingredient (Compl. ¶2, ¶15, ¶28). Tofacitinib functions as an inhibitor of Janus kinases (JAKs) and is approved for treating conditions such as rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis (Compl. ¶17). The complaint alleges that Alkem seeks to market its generic product prior to the December 8, 2025 expiration of the ’783 patent (Compl. ¶2, ¶20).
IV. Analysis of Infringement Allegations
No probative visual evidence provided in complaint.
Claim Chart Summary
The complaint pleads infringement based on the submission of the ANDA under 35 U.S.C. § 271(e)(2)(A). The core of the infringement allegation is that the product for which Alkem seeks FDA approval is the same chemical entity recited in the asserted patent claim.
| Claim Element (from Dependent Claim 4) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| 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. | The complaint alleges that Alkem's ANDA seeks approval for generic "Tofacitinib Citrate Tablets" (Compl. ¶28). It further alleges that the active ingredient in Pfizer's corresponding brand-name product, Xeljanz®, is tofacitinib citrate, which has the chemical name (3R,4R)-4-methyl-3-(methyl-7H-pyrrolo [2,3-d] pyrimidin-4-ylamino)-ẞ-oxo-1-piperidinepropanenitrile, 2-hydroxy-1,2,3-propanetricarboxylate (1:1) (Compl. ¶16). This chemical entity is a salt form of the compound recited in Claim 4. | ¶16, ¶28, ¶35 | col. 24:25-30 |
Identified Points of Contention
- Technical Questions: The complaint alleges that Alkem's detailed statement, provided with its Paragraph IV notice, "does not contain a noninfringement argument" (Compl. ¶32). This suggests that the central dispute may concern the patent's validity rather than a technical mismatch between the claim and the accused product.
- Scope Questions: The infringement analysis appears to be a direct comparison. The primary question is whether the chemical structure of tofacitinib, as described in Alkem's ANDA, is encompassed by the language of Claim 4. Given that Claim 4 recites the specific tofacitinib molecule or its salts, and the accused product is identified as "Tofacitinib Citrate Tablets," the infringement case may be straightforward, pending resolution of any validity challenges.
V. Key Claim Terms for Construction
- 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: This term defines the chemical structure of the entire asserted claim. A potential issue for construction is that the chemical name recited in the claim does not specify the stereochemistry of the molecule's chiral centers. The complaint, however, identifies the FDA-approved active ingredient as the specific "(3R,4R)" stereoisomer (Compl. ¶16). Practitioners may focus on this term because the interpretation of whether the claim covers a specific isomer, a mixture of isomers (a racemate), or all possible isomers will be critical to the infringement analysis.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The plain language of Claim 4 itself does not contain any stereochemical limitations (e.g., "R," "S," "cis," or "trans") (’783 Patent, col. 24:25-28). The specification states that the invention "relates to the use of all optical isomers and stereoisomers of the compounds of the present invention, and mixtures thereof," which may support a construction that covers more than a single isomer (’783 Patent, col. 7:27-30).
- Evidence for a Narrower Interpretation: A party seeking a narrower construction might point to specific examples or embodiments in the specification as context, although arguing that these implicitly limit claim scope is often challenging without a clear disavowal of other forms. The patent does not appear to contain an explicit disclaimer limiting the claimed compound to a single stereoisomer.
VI. Other Allegations
- Indirect Infringement: The complaint’s prayer for relief includes a request to enjoin future inducement of infringement (Compl., Prayer for Relief ¶C). However, the factual allegations in Count I focus on the ANDA filing as a statutory act of direct infringement and on future direct infringement upon commercialization, without providing a specific factual basis for a claim of inducement (Compl. ¶¶35-38).
- Willful Infringement: The complaint does not contain an explicit allegation of willful infringement. It does allege that "Alkem had knowledge of the RE’783 patent when it submitted ANDA No. 219885 to the FDA" (Compl. ¶36), which is a prerequisite for any such future claim.
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of validity: The complaint states that Defendant’s ANDA certification did not include a non-infringement argument, focusing instead on invalidity (Compl. ¶32). Consequently, the case will likely hinge on whether Defendant can prove by clear and convincing evidence that Claim 4 of the ’783 patent is invalid on grounds such as obviousness or lack of adequate written description.
- A secondary, but potentially dispositive, question will be one of claim scope: Does Claim 4, which is silent as to stereochemistry, cover the specific (3R,4R) isomer that constitutes the tofacitinib drug product? While infringement of a claim to a specific molecule by its generic equivalent is often straightforward, any ambiguity regarding the claimed stereoisomers versus the accused product could create a key point of dispute.