DCT

2:23-cv-22461

Catalyst Pharma Inc v. Inventia Healthcare Ltd

Log In

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:23-cv-22461, D.N.J., 11/17/2023
  • Venue Allegations: Venue is alleged to be proper in the District of New Jersey on the basis that Defendant conducts substantial business in the United States, including the district, and that the district is a likely destination for the accused generic drug product.
  • Core Dispute: Plaintiffs allege that Defendant’s submission of an Abbreviated New Drug Application to the FDA seeking approval to market a generic version of Plaintiffs’ Firdapse® (amifampridine) tablets constitutes an act of infringement of six U.S. patents.
  • Technical Context: The technology concerns the drug amifampridine, used for treating the rare neuromuscular disorder Lambert-Eaton Myasthenic Syndrome (LEMS), and methods for ensuring its purity and optimizing its administration based on patient genetics.
  • Key Procedural History: The lawsuit is a Hatch-Waxman action triggered by Defendant’s October 6, 2023 Notice Letter informing Plaintiffs of its Abbreviated New Drug Application (ANDA) No. 218760. The letter included a Paragraph IV certification, asserting that the patents-in-suit are invalid, unenforceable, and/or will not be infringed by the proposed generic product.

Case Timeline

Date Event
2011-06-30 Earliest Priority Date for ’893, ’128A, ’128B, ’331, and ’332 Patents
2016-06-10 Earliest Priority Date for ’088 Patent
2018-11-28 FDA Approval for Firdapse® (amifampridine) Tablets
2020-04-21 U.S. Patent No. 10,626,088 Issues
2020-10-06 U.S. Patent No. 10,793,893 Issues
2021-07-13 U.S. Patent No. 11,060,128 Issues
2022-03-08 U.S. Patent No. 11,268,128 Issues
2022-03-15 U.S. Patent No. 11,274,331 Issues
2022-03-15 U.S. Patent No. 11,274,332 Issues
2023-10-06 Defendant Inventia sends Notice Letter to Plaintiffs regarding ANDA submission
2023-11-17 Complaint for Patent Infringement Filed

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

No probative visual evidence provided in complaint.

U.S. Patent No. 10,626,088 - "Determining Degradation of 3,4-Diaminopyridine," Issued April 21, 2020

The Invention Explained

  • Problem Addressed: The patent describes a need for highly sensitive methods to detect and quantify degradation in samples of the drug 3,4-diaminopyridine, as impurities in pharmaceutical products can lead to adverse effects or decreased efficacy (’088 Patent, col. 1:19-34).
  • The Patented Solution: The invention identifies a specific degradation product—a dimer of 3,4-diaminopyridine—and claims this chemical compound itself. The patent describes using the presence or amount of this dimer as a reference marker to determine the purity and stability of a 3,4-diaminopyridine sample, for example via high-performance liquid chromatography (HPLC) (’088 Patent, Abstract; col. 1:47-59). The dimer is described as forming from the covalent linking of two 3,4-diaminopyridine molecules (’088 Patent, col. 4:11-13).
  • Technical Importance: The ability to detect and quantify specific, known degradation products is critical for pharmaceutical quality control, ensuring drug product safety, and determining shelf life (Compl. ¶20; ’088 Patent, col. 4:53-57).

Key Claims at a Glance

  • The complaint alleges infringement of one or more claims of the ’088 patent but does not specify which claims will be asserted (Compl. ¶37). Independent claim 1 is a composition of matter claim directed to:
    • A 3,4-Diaminopyridine dimer that is a specific chemical structure or a tautomer thereof
    • in the form of a salt, solvate, or complex, or a combination thereof

U.S. Patent No. 10,793,893 - "Methods of Administering 3,4-Diaminopyridine," Issued October 6, 2020

The Invention Explained

  • Problem Addressed: The patent discloses that the clinical response to 3,4-diaminopyridine (3,4-DAP) is highly variable among patients, with up to 10-fold differences in key pharmacokinetic parameters, which creates risks of side effects or lack of efficacy (’893 Patent, col. 2:12-24). The reason for this variability was not previously understood (Compl. ¶20; ’893 Patent, col. 2:21-23).
  • The Patented Solution: The invention is based on the discovery that patient-to-patient variability is explained by genetic polymorphisms in the N-acetyl transferase (NAT) enzymes responsible for metabolizing the drug (’893 Patent, col. 5:32-44). The patent claims methods of treatment that involve identifying a patient’s acetylator status (e.g., "slow" or "fast") based on their NAT2 genotype and administering a dose of 3,4-DAP adjusted to that status (’893 Patent, Abstract; col. 11:53-62).
  • Technical Importance: This invention provides a personalized medicine approach, allowing physicians to tailor drug dosage to an individual patient’s genetic makeup to optimize efficacy and minimize adverse events (Compl. ¶20).

Key Claims at a Glance

  • The complaint alleges infringement of one or more claims of the ’893 patent but does not specify which claims will be asserted (Compl. ¶45). Independent claim 1 is a method of treatment claim comprising:
    • A method of treating a human patient diagnosed with a 3,4-DAP sensitive disease
    • The patient is a slow acetylator having an N-acetyl transferase 2 (NAT2) gene comprising specific genetic mutations (a C282T mutation on both alleles; a T341C mutation on both alleles; or one of each)
    • The method comprises administering a dose of about 2.5 mg to about 30 mg of 3,4-DAP or a pharmaceutically acceptable salt thereof

U.S. Patent No. 11,060,128 - "Methods of Administering 3,4-Diaminopyridine," Issued July 13, 2021

  • Technology Synopsis: This patent, related to the ’893 patent, addresses the variability in patient response to 3,4-DAP. It claims methods for treating patients based on their specific genetic profile, identifying them as slow acetylators due to certain NAT2 gene mutations and administering an adjusted dose (Compl. ¶20, 23).
  • Asserted Claims: The complaint asserts one or more claims without specification (Compl. ¶53).
  • Accused Features: The proposed manufacture, use, and sale of Inventia's ANDA Product, which would be administered according to a label that Plaintiffs allege will induce infringement (Compl. ¶51-53).

U.S. Patent No. 11,268,128 - "Methods of Administering 3,4-Diaminopyridine," Issued March 8, 2022

  • Technology Synopsis: This patent, also related to the ’893 patent, addresses patient variability. It claims methods for treating "fast acetylator" patients, who metabolize the drug more quickly, by administering a higher dose of 3,4-DAP to achieve a therapeutic effect (Compl. ¶20, 24).
  • Asserted Claims: The complaint asserts one or more claims without specification (Compl. ¶61).
  • Accused Features: The proposed manufacture, use, and sale of Inventia's ANDA Product, which would be administered according to a label that Plaintiffs allege will induce infringement (Compl. ¶59-61).

U.S. Patent No. 11,274,331 - "Methods of Administering 3,4-Diaminopyridine," Issued March 15, 2022

  • Technology Synopsis: This patent, also related to the ’893 patent, addresses patient variability. It claims methods for treating "slow acetylator" patients with a specific dosage range of 3,4-DAP tailored to that metabolic profile (Compl. ¶20, 25).
  • Asserted Claims: The complaint asserts one or more claims without specification (Compl. ¶69).
  • Accused Features: The proposed manufacture, use, and sale of Inventia's ANDA Product, which would be administered according to a label that Plaintiffs allege will induce infringement (Compl. ¶67-69).

U.S. Patent No. 11,274,332 - "Methods of Administering 3,4-Diaminopyridine," Issued March 15, 2022

  • Technology Synopsis: This patent, also related to the ’893 patent, addresses patient variability. It claims methods for treating "fast acetylator" patients with a specific, higher dosage range of 3,4-DAP tailored to that metabolic profile (Compl. ¶20, 26).
  • Asserted Claims: The complaint asserts one or more claims without specification (Compl. ¶77).
  • Accused Features: The proposed manufacture, use, and sale of Inventia's ANDA Product, which would be administered according to a label that Plaintiffs allege will induce infringement (Compl. ¶75-77).

III. The Accused Instrumentality

Product Identification

  • Defendant Inventia’s Abbreviated New Drug Application ("ANDA") Product, which is a generic version of Catalyst’s Firdapse® (amifampridine) Tablets, 10 mg drug product (Compl. ¶1).

Functionality and Market Context

  • The complaint alleges that by filing its ANDA, Inventia has represented to the FDA that its generic product will have the same active ingredient (amifampridine), method of administration, dosage form, and strength as Firdapse®, and will be bioequivalent (Compl. ¶32). Amifampridine functions as a voltage-dependent potassium channel blocker that improves neuromuscular transmission and is used for the treatment of Lambert-Eaton Myasthenic Syndrome ("LEMS") (Compl. ¶¶15, 17). Firdapse® is described as the first FDA-approved product for the treatment of LEMS (Compl. ¶18).

IV. Analysis of Infringement Allegations

The complaint does not provide claim charts or detailed infringement contentions mapping specific product features to claim elements. The infringement allegations are framed generally.

  • ’088 Patent Infringement Allegations

    The complaint does not provide sufficient detail for analysis of infringement on a limitation-by-limitation basis. The infringement theory for the ’088 Patent appears to be that Defendant's manufacturing of the ANDA Product will necessarily result in a composition that contains the claimed 3,4-diaminopyridine dimer as a degradation product, thereby directly infringing the patent’s composition claims (Compl. ¶38).

  • ’893 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A method of treating a human patient diagnosed with a 3,4-diaminopyridine (3,4-DAP) sensitive disease... who is a slow acetylator having an N-acetyl transferase 2 (NAT2) gene comprising: a C282T mutation on both alleles..., a T341C mutation on both alleles..., or a C282T mutation on one allele... and a T341C mutation on the other allele... The complaint alleges that Defendant’s proposed package insert for its ANDA Product will instruct and encourage medical practitioners to administer the drug to patients, including those who are slow acetylators having the specified NAT2 gene mutations, for the treatment of LEMS. ¶45 col. 11:53-62
...administering a dose of about 2.5 mg to about 30 mg of 3,4-DAP or a pharmaceutically acceptable salt thereof. The ANDA product is a 10 mg tablet, and its proposed label will allegedly direct physicians to administer doses that fall within the claimed range to patients, including slow acetylators. ¶¶32, 45 col. 11:63-65
  • Identified Points of Contention:
    • Evidentiary Questions (’088 Patent): A primary question for the ’088 Patent will be evidentiary: can Plaintiffs demonstrate that the ANDA Product, as it will be commercially manufactured and sold by Inventia, will contain the specific 3,4-diaminopyridine dimer recited in the claims?
    • Scope and Inducement Questions (’893 Patent Family): For the method patents, a central issue may be induced infringement. The analysis will likely focus on whether Inventia's proposed product label encourages, recommends, or promotes an infringing use. This raises the question of whether the label will instruct physicians to perform the patented steps of determining a patient’s acetylator genotype and adjusting dosage accordingly, as required by the claims.

V. Key Claim Terms for Construction

  • The Term: "slow acetylator" (’893 Patent, claim 1)
    • Context and Importance: The scope of the asserted method claims in the ’893 patent and its relatives hinges on the definition of patient subpopulations, such as "slow acetylator" and "fast acetylator." Practitioners may focus on this term because the claims explicitly tie the definition to specific genetic mutations, which could be a point of dispute regarding both infringement and validity.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Narrower Interpretation: The language of claim 1 of the ’893 patent itself provides a definition: "a human patient who is a slow acetylator having an N-acetyl transferase 2 (NAT2) gene comprising: a C282T mutation on both alleles..., a T341C mutation on both alleles..., or a C282T mutation on one allele... and a T341C mutation on the other..." This structure suggests the term is expressly defined by the listed genotypes.
      • Evidence for a Broader Interpretation: The specification describes multiple ways to determine acetylator status, including functional tests like a caffeine challenge, not just genetic testing (’893 Patent, col. 11:46-62). A party could argue that the term should be understood in this broader functional context, though the claim language may present a challenge to this position.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement for all six patents-in-suit. The basis for inducement is the allegation that Inventia’s proposed package insert will instruct and encourage medical practitioners and patients to use the ANDA Product in an infringing manner (e.g., Compl. ¶¶37, 45). The basis for contributory infringement is the allegation that Inventia knows its product is especially adapted for infringing uses and is not suitable for substantial non-infringing use (e.g., Compl. ¶¶38, 46).
  • Willful Infringement: The complaint does not use the term "willful infringement." However, for each patent, it alleges that Inventia has had knowledge of the patent since at least the date it submitted its ANDA and requests that the court find the case "exceptional" and award attorneys' fees under 35 U.S.C. § 285 (e.g., Compl. ¶¶40-41, 48-49). These allegations could form the basis for a later claim for enhanced damages.

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

  • A central issue will be one of inducement: For the five asserted method patents, can Plaintiffs prove that Inventia’s proposed product label, which is expected to mirror the Firdapse® label, provides sufficient instruction or encouragement for physicians to perform the patented method of genotyping patients and adjusting dosage based on their specific "slow" or "fast" acetylator status?
  • A key evidentiary question will be one of compositional proof: For the ’088 patent, can Plaintiffs produce evidence that the generic drug Inventia will manufacture and sell actually contains the specific 3,4-diaminopyridine dimer claimed in the patent, and if so, whether its presence constitutes infringement?
  • The outcome may also turn on claim scope: How will the court construe the term "slow acetylator"? Will its meaning be strictly limited to the specific genetic mutations recited within the claims, or will it be interpreted more broadly to encompass functional definitions described elsewhere in the patent specification?