DCT

1:25-cv-01440

Vifor Fresenius Medical Care Renal Pharma Ltd v. MSN Laboratories Pvt Ltd

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-01440, D. Del., 11/26/2025
  • Venue Allegations: Plaintiff alleges venue is proper in the District of Delaware because Defendant MSN Pharmaceuticals is a Delaware corporation and Defendant MSN Laboratories has committed acts of infringement in Delaware, purposefully avails itself of the rights of Delaware law, and has previously consented to personal jurisdiction in the district.
  • Core Dispute: Plaintiff alleges that Defendant’s filing of an Abbreviated New Drug Application (ANDA) for a generic version of the drug KORSUVA® constitutes an act of patent infringement.
  • Technical Context: The technology involves synthetic peptide amides that function as kappa opioid receptor agonists, designed to treat conditions like pruritus associated with chronic kidney disease while minimizing central nervous system side effects.
  • Key Procedural History: The action was triggered by Plaintiff’s receipt of a Paragraph IV Certification Letter on October 17, 2025, in which Defendant asserted that the patent-in-suit is invalid, unenforceable, and/or will not be infringed by its proposed generic product. The patent-in-suit is listed in the U.S. Food and Drug Administration's "Orange Book" as covering Plaintiff's KORSUVA® drug product.

Case Timeline

Date Event
2006-11-10 ’564 Patent Priority Date
2008-07-22 ’564 Patent Issue Date
2021-08-01 KORSUVA® FDA Approval Date (stated as August 2021)
2025-10-17 Plaintiff Received Defendant's Paragraph IV Certification Letter
2025-11-26 Complaint Filing Date

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

U.S. Patent No. 7,402,564 - "Synthetic Peptide Amides"

  • Patent Identification: U.S. Patent No. 7,402,564 ("Synthetic Peptide Amides"), issued July 22, 2008.

The Invention Explained

  • Problem Addressed: The patent background describes kappa opioid receptors as therapeutic targets for a wide array of conditions, including neuropathic and visceral pain, inflammation, and pruritus (’564 Patent, col. 1:19-col. 2:47). A central challenge with opioid agonists is avoiding undesirable central nervous system (CNS) effects.
  • The Patented Solution: The invention discloses synthetic peptide amides designed to be selective kappa opioid receptor agonists that exhibit low penetration into the brain (’564 Patent, Abstract). By acting primarily on peripheral receptors, these compounds aim to provide therapeutic benefits, such as pain or itch relief, while minimizing or obviating CNS side effects like sedation and dysphoria commonly associated with opioids that cross the blood-brain barrier (’564 Patent, col. 19:5-22). The core of the invention is a general chemical structure, Formula I, that defines a class of these peptide amides (’564 Patent, col. 3:5-10).
  • Technical Importance: Developing peripherally-selective opioid agonists was a significant goal in pharmacology, offering a pathway to separate the desired analgesic or anti-pruritic effects from the problematic CNS-related side effects of conventional opioids (’564 Patent, col. 19:5-22).

Key Claims at a Glance

  • The complaint asserts infringement of at least claim 1 (Compl. ¶33).
  • Independent Claim 1 recites a synthetic peptide amide with a general formula comprising a tetrapeptide portion and a cyclic moiety, with its essential elements including:
    • A synthetic peptide amide having the formula: Xaa₁-Xaa₂-Xaa₃-Xaa₄-W-[cyclic moiety]
    • wherein Xaa₁Xaa₂ is D-Phe-D-Phe
    • Xaa₃ is D-Leu or D-Nle
    • Xaa₄ is selected from a Markush group of D-amino acids, including D-Lys
    • The linking moiety W is null, -NH-(CH₂)b-, or -NH-(CH₂)c-O-
    • The cyclic moiety is selected from a group of specific chemical structures depicted in the claim
  • The complaint does not explicitly reserve the right to assert dependent claims, but the prayer for relief seeks judgment of infringement of "one or more claims" of the ’564 Patent (Compl., Prayer for Relief ¶A).

III. The Accused Instrumentality

Product Identification

  • The accused product is the "MSN Proposed ANDA Product," identified as "difelikefalin injection, 65 mcg/1.3 mL (50 mcg/mL), single dose vials" (Compl. ¶12).

Functionality and Market Context

  • The product is a proposed generic version of Plaintiff's KORSUVA® drug, for which MSN has filed an Abbreviated New Drug Application (ANDA) with the FDA (Compl. ¶1, ¶12). KORSUVA® is a kappa opioid receptor agonist used for the treatment of moderate-to-severe pruritus in adult patients undergoing hemodialysis (Compl. ¶9). The complaint alleges that MSN's product contains the active ingredient difelikefalin acetate and claims bioequivalence to KORSUVA® (Compl. ¶33). The filing of the ANDA seeks approval to market this generic product before the expiration of the ’564 Patent (Compl. ¶12).

IV. Analysis of Infringement Allegations

The complaint does not contain a claim chart or detailed, element-by-element infringement allegations. The infringement theory is based on the legal framework of the Hatch-Waxman Act, where the act of filing an ANDA for a generic version of a branded drug is a statutory act of infringement (Compl. ¶31). The complaint alleges that because the MSN Proposed ANDA Product contains difelikefalin acetate and is bioequivalent to KORSUVA®, and because the ’564 Patent's claims cover difelikefalin, the proposed generic product will necessarily infringe (Compl. ¶¶10, 33-34).

No probative visual evidence provided in complaint.

  • Identified Points of Contention:
    • Scope Questions: A principal dispute will likely concern whether the specific chemical structure of difelikefalin falls within the scope of the asserted claims, particularly the complex Markush structure of independent claim 1. Defendant’s non-infringement position, as stated in its Paragraph IV letter, suggests it will argue that its product is outside the patent's properly construed scope (Compl. ¶14).
    • Technical Questions: The complaint does not provide sufficient detail for analysis of technical mismatches in the accused product's formulation. The core technical question for infringement will be the structural mapping of difelikefalin to the limitations of the asserted patent claims.

V. Key Claim Terms for Construction

  • The Term: The various structural limitations of Claim 1, including the definitions for the fourth amino acid ("Xaa₄") and the attached cyclic moiety.
  • Context and Importance: Infringement in this ANDA litigation will turn on whether the specific molecule, difelikefalin, is encompassed by the asserted claim(s). Practitioners may focus on these terms because the defendant's non-infringement defense likely depends on arguing for a narrow construction that excludes the precise structure of difelikefalin.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: A party advocating for broader scope may point to the plain language of Claim 1, which provides a list of alternative chemical structures for the Xaa₄ and cyclic moiety elements. They may also cite dependent claim 2, which explicitly recites the structure of "Compound (2)," alleged to be difelikefalin, as falling within the scope of claim 1, thereby serving as an explicit definition (’564 Patent, col. 85:20-41).
    • Evidence for a Narrower Interpretation: A party advocating for narrower scope may argue that definitions or specific embodiments in the patent's detailed description limit the terms in Claim 1 in a way that carves out the difelikefalin structure (’564 Patent, col. 11:1-col. 16:65). They may also argue that the specific representation of "Compound (2)" in Claim 2 suggests it is a distinct species, and that the broader genus of Claim 1 should not automatically be read to include it without ambiguity.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges that upon approval and commercialization, MSN will induce infringement by others, such as doctors and patients, by providing instructions for use in the proposed package insert (Compl. ¶34, ¶37). It also alleges contributory infringement on the basis that the proposed product is not a staple article of commerce and is especially adapted for an infringing use (Compl. ¶36).
  • Willful Infringement: The complaint alleges that MSN has had knowledge of the ’564 Patent at least since the date it submitted its ANDA and was aware that its submission constituted an act of infringement (Compl. ¶35). The complaint further notes that MSN’s Paragraph IV letter, which discussed the ’564 Patent, evidences pre-suit knowledge (Compl. ¶37).

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

The resolution of this case will likely depend on the court's determination of two central issues inherent in ANDA litigation:

  • A core issue will be one of claim scope and construction: Will the court construe the asserted claims of the ’564 Patent, particularly the Markush language in Claim 1, to unambiguously cover the chemical structure of difelikefalin, the active ingredient in MSN's proposed generic product?
  • A second critical issue will be patent validity: Can MSN meet its burden of proving by clear and convincing evidence that the asserted claims of the ’564 Patent are invalid on grounds such as obviousness, anticipation, or lack of written description, as asserted in its Paragraph IV certification?