DCT

1:24-cv-10820

Merck Sharp & Dohme LLC v. Aic246 Ag & Co KG

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:24-cv-10820, D.N.J., 11/27/2024
  • Venue Allegations: Venue is alleged to be proper in the District of New Jersey because Defendant Zydus USA has its principal place of business in the state, and Defendant Zydus Lifesciences is subject to personal jurisdiction and has previously consented to venue in the district.
  • Core Dispute: Plaintiffs allege that Defendants’ submission of an Abbreviated New Drug Application (ANDA) for a generic version of the antiviral drug PREVYMIS® (letermovir) constitutes an act of infringement of a patent covering the letermovir compound.
  • Technical Context: The technology concerns novel antiviral compounds for the prophylaxis of cytomegalovirus (CMV), a common virus that can cause serious infection and disease in immunocompromised individuals, particularly transplant recipients.
  • Key Procedural History: The action was initiated under the Hatch-Waxman Act following Plaintiffs’ receipt of a Notice Letter dated October 16, 2024, in which Zydus stated it had filed an ANDA with a Paragraph IV certification, asserting that the patent-in-suit is invalid, unenforceable, or will not be infringed by the generic product.

Case Timeline

Date Event
2003-05-02 RE '791 Patent Priority Date
2018-04-17 RE '791 Patent Issue Date (Reissue)
2024-10-16 Zydus sends Notice Letter to Plaintiffs
2024-11-27 Complaint Filing Date

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

U.S. Reissued Patent No. RE 46,791 - Substituted Dihydroquinazolines

  • Patent Identification: U.S. Reissued Patent No. RE 46,791, "Substituted Dihydroquinazolines", issued April 17, 2018.

The Invention Explained

  • Problem Addressed: The patent addresses the need for new antiviral therapies, noting that the development of drug resistance to existing agents is an ongoing concern, particularly for viral infections like cytomegalovirus (CMV) (RE '791 Patent, col. 1:21-23).
  • The Patented Solution: The invention provides a class of chemical compounds known as "substituted dihydroquinazolines," defined by a general Markush structure (Formula I), which are asserted to have an antiviral effect against viruses in the Herpes family, especially human cytomegalovirus (HCMV) (RE '791 Patent, Abstract; col. 11:15-19).
  • Technical Importance: Developing new classes of antiviral agents is critical for managing infections in high-risk, immunocompromised populations, such as organ and stem cell transplant recipients, for whom CMV infection can be life-threatening (Compl. ¶18).

Key Claims at a Glance

  • The complaint asserts dependent claims 23 and 24, which incorporate all the limitations of independent claim 1.
  • Independent Claim 1 recites:
    • A compound of a general formula (I), which defines a broad genus of substituted dihydroquinazoline structures.
    • The formula includes multiple variable substituent groups (Ar, R¹-R⁸) at various positions on the core chemical scaffold, creating a large Markush group.
    • The claim also covers a salt, solvate, or solvate of a salt of the compound.
  • The complaint does not foreclose the possibility of asserting other claims.

III. The Accused Instrumentality

Product Identification

  • The accused instrumentality is "Zydus's ANDA Product," a generic version of PREVYMIS® tablets intended for oral administration in 240 mg and 480 mg strengths (Compl. ¶ Nature of Action, ¶37).

Functionality and Market Context

  • The active pharmaceutical ingredient (API) in the Zydus ANDA Product is letermovir (Compl. ¶37). The product is intended to be used for the prophylaxis of CMV infection and disease in adult and pediatric transplant recipients (Compl. ¶18).
  • The Zydus ANDA filing relies on the FDA's prior approval of Plaintiffs' PREVYMIS® and contains data intended to demonstrate the bioequivalence of Zydus's product (Compl. ¶38). If approved, it would be marketed as a direct competitor to PREVYMIS® (Compl. ¶ Nature of Action).

IV. Analysis of Infringement Allegations

RE '791 Patent Infringement Allegations

Claim Element (from Dependent Claim 23) Alleged Infringing Functionality Complaint Citation Patent Citation
The compound of claim 1, wherein said compound is: [chemical structure] The active ingredient of Zydus's ANDA Product is alleged to be letermovir, which Plaintiffs contend is the specific compound recited in claim 23. The complaint provides a chemical diagram of the compound allegedly recited in claim 23 (Compl. ¶30). ¶30, ¶37 col. 124:7-12
or a physiologically acceptable salt thereof. Zydus's ANDA Product is a pharmaceutical formulation containing letermovir, which would fall under the claim's scope whether it is the base compound or a salt form. ¶37 col. 124:13-14

Identified Points of Contention

  • Scope Questions: The complaint alleges that Zydus, in its notice letter, did not provide a basis for an assertion of non-infringement of claims 23 and 24 (Compl. ¶35). This suggests the primary dispute may not be over infringement but rather the validity of the patent, which Zydus challenged in its Paragraph IV certification (Compl. ¶34). The central infringement question for the court will be one of identity: is the specific letermovir compound, including its stereochemistry, contained in Zydus’s ANDA product the same chemical entity defined by the asserted claims?
  • Technical Questions: Given that Zydus's ANDA seeks approval for a generic version of PREVYMIS®, whose active ingredient is letermovir, there may be little technical dispute that the molecule is the same. The focus will likely shift to whether the patent claims covering that molecule are valid and enforceable.

V. Key Claim Terms for Construction

  • The Term: "the compound"
  • Context and Importance: In a case involving a specific chemical entity, the interpretation of "the compound" is dispositive. Practitioners may focus on this term because its scope, particularly with respect to its specific three-dimensional stereochemical structure, will determine whether the letermovir in Zydus's product literally infringes. Claims 23 and 24 recite a specific stereoisomer.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification includes general language stating that the invention "relates to the enantiomers or diastereomers and respective mixtures thereof," which could be argued to support a scope not strictly limited to a single stereoisomer unless a claim is explicit (RE '791 Patent, col. 3:35-38).
    • Evidence for a Narrower Interpretation: The patent defines a symbol (*) on a carbon atom to mean the compound is present in "enantiomerically pure form," defined as an enantiomeric excess of more than 90% (RE '791 Patent, col. 4:63-68). The specific chemical structures depicted in the asserted claims (e.g., claim 23) show a particular stereochemistry, which would support a narrow construction limited to that specific molecule.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges that Zydus will induce infringement by marketing its ANDA product with a label that instructs and encourages administration for the prophylaxis of CMV infection, a use covered by the patent (Compl. ¶42, ¶43). It also alleges contributory infringement, asserting that the Zydus product is especially made for infringing uses and is not suitable for substantial noninfringing use (Compl. ¶44).
  • Willful Infringement: The complaint alleges that Zydus has knowledge of the RE '791 patent at least from its listing in the FDA's Orange Book for PREVYMIS® and that Zydus's continued actions constitute willful infringement (Compl. ¶41).

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

  • A core issue will be one of chemical identity: Will the evidence confirm that the letermovir compound in Zydus’s ANDA product is the exact chemical structure, including the specific stereoisomerism, recited in the asserted claims of the '791 patent? In ANDA litigation, this is often presumed, shifting the focus elsewhere.
  • The dispositive question will likely be one of patent validity: Although the complaint does not detail Zydus’s invalidity theories, the Paragraph IV certification ensures that the validity and enforceability of the '791 patent, which Zydus has formally challenged, will be the central battleground of the litigation.