DCT

1:24-cv-00621

Pfizer Inc v. Apotex Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:24-cv-00621, D. Del., 05/23/2024
  • Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendant Apotex Corp. is incorporated in Delaware, and because Defendant Apotex Inc. is a foreign corporation that may be sued in any judicial district.
  • Core Dispute: Plaintiffs allege that Defendants' submission of an Abbreviated New Drug Application (ANDA) to market a generic version of NURTEC ODT® (rimegepant sulfate) infringes three U.S. patents covering the rimegepant compound, a specific salt form, and a pharmaceutical formulation.
  • Technical Context: The technology concerns small-molecule Calcitonin Gene-Related Peptide (CGRP) receptor antagonists, a class of drugs used for the acute and preventive treatment of migraine headaches.
  • Key Procedural History: The litigation was initiated under the Hatch-Waxman Act following Defendants' submission of ANDA No. 219399 and a Paragraph IV certification, which asserted that the patents-in-suit would not be infringed by the proposed generic product. The complaint was filed within the 45-day statutory window following receipt of the Defendants' notice letter.

Case Timeline

Date Event
2009-10-14 ’117 Patent Priority Date
2012-02-27 ’372 Patent Priority Date
2012-11-20 ’117 Patent Issue Date
2014-06-24 ’372 Patent Issue Date
2018-03-25 ’724 Patent Priority Date
2021-08-10 ’724 Patent Issue Date
2024-04-18 Apotex Paragraph IV Notice Letter Date
2024-05-23 Complaint Filing Date

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

U.S. Patent No. 8,314,117 - "CGRP Receptor Antagonists"

The Invention Explained

  • Problem Addressed: The patent background describes the role of CGRP in migraine pathophysiology and notes that existing "triptan" drugs, while effective for some, carry cardiovascular liabilities due to their vasoconstrictive mechanism (’117 Patent, col. 2:1-21). This created a need for novel migraine treatments without these side effects.
  • The Patented Solution: The invention provides a class of novel small-molecule compounds that act as CGRP receptor antagonists, thereby blocking the CGRP pathway implicated in migraines without causing the vasoconstriction associated with triptans (’117 Patent, Abstract; col. 2:15-21). The asserted claim protects a specific chemical entity, rimegepant, which embodies this solution.
  • Technical Importance: The development of CGRP receptor antagonists represented a targeted therapeutic approach for migraine that could potentially be used by patients with cardiovascular contraindications to triptans (’117 Patent, col. 2:15-21).

Key Claims at a Glance

  • The complaint asserts claim 14, which is dependent on claim 1 (Compl. ¶38, 50).
  • Claim 14, incorporating claim 1, covers:
    • The specific compound (5S,6S,9R)-5-amino-6-(2,3-difluorophenyl)-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridin-9-yl 4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-1-yl)piperidine-1-carboxylate (rimegepant).
    • or a pharmaceutically acceptable salt thereof.
  • The complaint alleges infringement of "one or more claims" of the ’117 Patent, suggesting other claims may be asserted later (Compl. ¶36).

U.S. Patent No. 8,759,372 - "N-(5S,6S,9R)-5-Amino-6-(2,3-Difluorophenyl)-6,7,8,9-Tetrahydro-5H-Cyclohepta[b]Pyridin-9-yl-4-(2-Oxo-2,3-Dihydro-1H-Imidazo[4,5-b]Pyridin-1-Carboxylate Salt"

The Invention Explained

  • Problem Addressed: The patent explains that the bioavailability of the base compound (rimegepant) can be highly variable due to its pH-dependent dissolution rate, which is a significant challenge for developing a reliable oral medication (’372 Patent, col. 2:10-24).
  • The Patented Solution: The invention claims a specific salt form of rimegepant—the hemisulfate salt. This particular salt form is described as surprisingly reducing bioavailability variability and providing consistency among patients, thereby creating a more reliable drug product (’372 Patent, Abstract; col. 2:49-59).
  • Technical Importance: Identifying a salt form with stable and predictable absorption characteristics is a critical step in pharmaceutical development, as it directly impacts a drug's safety and efficacy profile (’372 Patent, col. 2:5-9).

Key Claims at a Glance

  • The complaint asserts independent claim 1 (Compl. ¶63, 75).
  • Claim 1 recites:
    • A hemisulfate salt
    • of Compound (I), which is identified by its chemical structure as rimegepant.
  • The complaint alleges infringement of "one or more claims" of the ’372 Patent (Compl. ¶61).

U.S. Patent No. 11,083,724 - "Rimegepant for CGRP Related Disorders"

The Invention Explained

This patent addresses the need for effective treatments for CGRP-related disorders by claiming a specific pharmaceutical composition of rimegepant or its salts (’724 Patent, col. 2:51-54; Abstract). The invention is directed to an "oral solid molded fast-dispersing dosage form" containing the active ingredient, designed for rapid administration and onset of action (’724 Patent, col. 5:1-3).

Key Claims and Accused Features

  • Asserted Claims: Independent claim 1 is asserted (Compl. ¶88, 100).
  • Accused Features: The complaint alleges that Apotex's ANDA Product is a pharmaceutical composition of rimegepant sulfate that will be in the form of an "oral solid molded fast-dispersing dosage form," thereby infringing this patent (Compl. ¶89).

III. The Accused Instrumentality

Product Identification

The accused instrumentality is Defendants’ proposed generic rimegepant sulfate orally disintegrating tablet, identified as the "Apotex ANDA Product" associated with ANDA No. 219399 (Compl. ¶1, 14).

Functionality and Market Context

The Apotex ANDA Product is alleged to be a generic copy of Pfizer's NURTEC ODT®, containing rimegepant sulfate as the active pharmaceutical ingredient (Compl. ¶1, 16). It is designed as an orally disintegrating tablet for the acute and preventive treatment of migraine in adults (Compl. ¶12). The complaint alleges the product relies on Pfizer’s New Drug Application for NURTEC ODT® and purports to be bioequivalent (Compl. ¶17). The product is intended for commercial manufacture, use, and sale in the United States upon FDA approval (Compl. ¶14).

IV. Analysis of Infringement Allegations

U.S. Patent No. 8,314,117 Infringement Allegations

Claim Element (from Independent Claim 1, via dependent Claim 14) Alleged Infringing Functionality Complaint Citation Patent Citation
The compound ... (5S,6S,9R)-5-amino-6-(2,3-difluorophenyl)-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridin-9-yl 4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-1-yl)piperidine-1-carboxylate; or a pharmaceutically acceptable salt thereof. Apotex's ANDA Product contains rimegepant sulfate, which is alleged to be a pharmaceutically acceptable salt of the claimed compound, rimegepant. The complaint provides a chemical structure diagram of the claimed compound. (Compl. p. 8). ¶39, ¶51 col. 78:13-27

Identified Points of Contention

  • Scope Questions: The complaint's theory appears to rest on a straightforward application of the claim language. A potential, though likely weak, point of contention could be whether "rimegepant sulfate" as formulated in the accused product qualifies as a "pharmaceutically acceptable salt" within the meaning of the patent.
  • Technical Questions: The primary dispute is unlikely to be technical but rather legal, focusing on the validity of the patent, an issue outside the allegations of the complaint. Infringement appears to depend simply on the chemical identity of the active ingredient in the ANDA product.

U.S. Patent No. 8,759,372 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A hemisulfate salt of Compound (I): [structure depicted] The Apotex ANDA Product is alleged to contain a hemisulfate salt of rimegepant. The complaint includes a diagram of the claimed chemical structure. (Compl. p. 12). ¶64, ¶76 col. 29:1-20

Identified Points of Contention

  • Scope Questions: The dispute may center on the precise definition of "A hemisulfate salt." While the term has a standard chemical meaning (a 1:0.5 molar ratio of base to sulfuric acid), the infringement analysis will depend on whether the salt form in Apotex's product meets this specific stoichiometric requirement.
  • Technical Questions: A key evidentiary question will be the characterization of the active ingredient in the Apotex ANDA Product. What is the exact molar ratio of rimegepant to sulfate, and does it correspond to the claimed "hemisulfate" form, as opposed to another sulfate salt or a mixture?

V. Key Claim Terms for Construction

The Term

"oral solid molded fast-dispersing dosage form" (’724 Patent, claim 1)

Context and Importance

The construction of this term will be central to determining infringement of the ’724 patent. The dispute will likely focus on whether Apotex's method for manufacturing its orally disintegrating tablet falls within the scope of "molded," a term that may imply a specific manufacturing process. Practitioners may focus on this term because different ODT technologies exist, and the patent's description may be used to argue for a scope limited to the technology disclosed.

Intrinsic Evidence for Interpretation

  • Evidence for a Broader Interpretation: The specification defines a "fast-dispersing dosage form" functionally as one that disintegrates or disperses within 1 to 60 seconds after contact with a fluid like saliva, a definition that could encompass a variety of ODT products (’724 Patent, col. 10:1-7).
  • Evidence for a Narrower Interpretation: The detailed description explains that the dosage forms can be prepared by a process involving sublimation of a solvent from a composition in a solid state, such as freeze-drying within a mold (’724 Patent, col. 10:10-25). A party could argue that the term "molded" limits the claim to dosage forms created through such a specific process, rather than, for example, simple compression.

VI. Other Allegations

Indirect Infringement

The complaint alleges both induced and contributory infringement for all three patents-in-suit. The allegations state that Defendants know their product is especially made or adapted for infringing uses and is not suitable for any substantial non-infringing use (e.g., Compl. ¶42, 67, 92). The complaint further alleges that if the ANDA is approved, Defendants intend to and will actively induce infringement (e.g., Compl. ¶41, 66, 91).

Willful Infringement

Willfulness is alleged based on Defendants having "acted with full knowledge" of the patents-in-suit and "without a reasonable basis for believing that they would not be liable for infringement" (e.g., Compl. ¶40, 65, 90). This knowledge is predicated on the Paragraph IV certification process required for the ANDA filing. Plaintiffs also seek a finding that the case is exceptional under 35 U.S.C. § 285 (e.g., Compl. ¶45, 70, 95).

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

  • A central factual question will be one of chemical identity: does the "rimegepant sulfate" in Apotex's proposed generic product contain the specific "hemisulfate salt" of rimegepant as claimed by the ’372 patent, or is there a distinction in the salt's stoichiometry or crystalline form?
  • A key issue of claim scope will be whether the manufacturing process for Apotex's orally disintegrating tablet results in an "oral solid molded fast-dispersing dosage form" as that term is defined and used within the context of the '724 patent's specification.
  • An underlying issue, characteristic of ANDA litigation, will be the validity of the asserted claims. Although not detailed in the complaint, the Defendants' Paragraph IV certification inherently challenges the validity and/or enforceability of the patents-in-suit, which will likely form the core of the defense.