DCT

1:19-cv-00311

Merck Sharp & Dohme Corp v. Anchen Pharma Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:19-cv-00311, D. Del., 02/13/2019
  • Venue Allegations: Venue is alleged to be proper as to Anchen because it is a Delaware corporation. Venue is alleged to be proper as to Par because it is subject to personal jurisdiction in the district and has previously consented to venue in the district.
  • Core Dispute: Plaintiff alleges that Defendants’ submission of an Abbreviated New Drug Application (ANDA) for a generic version of the diabetes drug JANUMET XR® constitutes an act of infringement of a patent covering a specific salt form of the active ingredient sitagliptin.
  • Technical Context: The patent relates to a specific dihydrogenphosphate salt of a dipeptidyl peptidase-IV (DPP-4) inhibitor, a class of compounds used to treat Type 2 diabetes by enhancing the body's own ability to lower elevated blood sugar.
  • Key Procedural History: The lawsuit was triggered by Defendants’ submission of ANDA No. 204144 to the U.S. Food and Drug Administration. The complaint states that Defendants provided notice letters to Plaintiff in 2012 containing a Paragraph IV certification, which asserts that the patent-in-suit is invalid, unenforceable, and/or will not be infringed. The complaint further alleges that in these notice letters, Defendants did not contest infringement of claim 1 of the patent.

Case Timeline

Date Event
2003-06-24 U.S. Patent No. 7,326,708 Priority Date
2008-02-05 U.S. Patent No. 7,326,708 Issue Date
2012-08-13 Anchen sends first Notice Letter to Merck regarding ANDA
2012-10-22 Anchen sends second Notice Letter to Merck regarding ANDA
2019-02-13 Complaint Filing Date

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

U.S. Patent No. 7,326,708 - Phosphoric Acid Salt of a Dipeptidyl Peptidase-IV Inhibitor

The Invention Explained

  • Problem Addressed: The patent's background section notes that while a class of beta-amino tetrahydrotriazolo[4,3-a]pyrazines were known to be potent inhibitors of the enzyme dipeptidyl peptidase-IV (DP-IV) for treating Type 2 diabetes, there was no specific disclosure of the particular salt form that is the subject of the invention ('708 Patent, col. 1:49-62). Developing specific, stable salt forms of active pharmaceutical ingredients is a critical step in creating a viable drug product.
  • The Patented Solution: The invention is a novel monobasic dihydrogenphosphate salt of a specific DP-IV inhibitor, 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine, also known as sitagliptin ('708 Patent, col. 2:44-52). This particular salt form, especially as a crystalline monohydrate, is described as possessing advantageous properties over other forms, including improved physical and chemical stability, which facilitates "ease of processing, handling, and dosing" in pharmaceutical manufacturing ('708 Patent, col. 2:4-18).
  • Technical Importance: The creation of a stable, crystalline salt form with favorable physicochemical properties is crucial for consistent manufacturing, formulation of effective dosage forms, and ensuring a stable shelf life for a pharmaceutical product ('708 Patent, col. 2:8-18).

Key Claims at a Glance

  • The complaint asserts infringement of at least independent claim 1 ('708 Patent, col. 16:10-16; Compl. ¶33).
  • The essential elements of independent claim 1 are:
    • A dihydrogenphosphate salt of 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine of structural formula I
    • or a hydrate thereof.
  • The complaint alleges infringement of "one or more claims" of the '708 patent, suggesting the right to assert other claims, including dependent claims, is reserved (Compl. ¶33).

III. The Accused Instrumentality

Product Identification

The accused instrumentality is Defendants' proposed generic drug product described in ANDA No. 204144 ("Anchen's ANDA Product"), which is a generic version of Merck's JANUMET XR® (metformin hydrochloride; sitagliptin phosphate extended release tablets) (Compl. ¶¶1, 3).

Functionality and Market Context

The infringement allegation centers on the sitagliptin component of the proposed generic drug. The complaint alleges that "Anchen's ANDA Product contains sitagliptin phosphate as an active ingredient" (Compl. ¶32). The submission of the ANDA is an artificial act of infringement under 35 U.S.C. § 271(e)(2), aimed at gaining FDA approval to market this generic drug in the United States before the expiration of the '708 Patent (Compl. ¶35).

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

Claim Chart Summary

The complaint does not contain a formal claim chart, but its allegations provide a basis for one.

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A dihydrogenphosphate salt of 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine... The complaint alleges that Defendants' ANDA product "contains sitagliptin phosphate as an active ingredient" and that this active ingredient is covered by claim 1. Sitagliptin is the common name for the chemical compound recited in the claim. ¶32, ¶33 col. 2:44-62
... or a hydrate thereof. The complaint alleges that claim 1 as a whole "covers the sitagliptin phosphate contained in Anchen's ANDA Product." The complaint does not specify whether the accused product is a hydrate, but the allegation is broad enough to read on this limitation if the product is a hydrate. ¶33 col. 16:15-16

Identified Points of Contention

  • Strategic Question: A central issue arises from the complaint's assertion that "Defendants did not contest infringement of claim 1 of the '708 patent" in their pre-suit notice letters (Compl. ¶34). This raises the question of whether the primary legal battle will be over the patent's validity and/or enforceability, which Defendants raised in their Paragraph IV certification (Compl. ¶31), or whether non-infringement arguments will nevertheless be advanced in litigation.
  • Technical Question: The complaint does not provide sufficient detail for analysis of the specific crystalline form or hydration state of the sitagliptin phosphate in the accused ANDA product. Should infringement be contested, a key technical question will be whether the specific physical form of the active ingredient in the accused product meets the limitations of the asserted claims, particularly in view of the patent's extensive focus on a "crystalline monohydrate" form ('708 Patent, Abstract, col. 2:54-56).

V. Key Claim Terms for Construction

  • The Term: "a hydrate thereof"
  • Context and Importance: This term appears in independent claim 1 and defines an alternative to the anhydrous salt form. The patent specification places significant emphasis on a specific "crystalline monohydrate" form ('708 Patent, Abstract). Practitioners may focus on this term because its construction could determine whether the claim scope is limited to the specific, well-characterized monohydrate, or if it also covers other hydrated forms (e.g., dihydrates, non-crystalline hydrates, or other polymorphs of a hydrate) that the accused product might contain.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language itself uses the indefinite article "a" and the general term "hydrate" without any specific stoichiometric limitation (e.g., "mono-", "di-"). This language may support an interpretation that the claim covers any hydrated form of the sitagliptin dihydrogenphosphate salt ('708 Patent, col. 16:16).
    • Evidence for a Narrower Interpretation: The specification repeatedly refers to and characterizes a specific "crystalline monohydrate" ('708 Patent, col. 2:3-4, 2:54). The abstract, figures, and detailed examples are all directed to this specific form. A party could argue that these specific disclosures limit the scope of the broader term "a hydrate" to the monohydrate form that the inventors described as their invention.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges active inducement of infringement, stating that Defendants "plan and intend to...actively induce infringement" and that the proposed product labeling will direct infringing use by medical professionals and patients (Compl. ¶¶38-39). The complaint also alleges contributory infringement, asserting that the ANDA product is not a staple article of commerce, is not suitable for substantial non-infringing use, and is especially made or adapted for infringement (Compl. ¶40).
  • Willful Infringement: The willfulness allegation is based on Defendants' alleged "full knowledge of the '708 patent," stemming from the notice letters sent in 2012 (Compl. ¶¶30, 43). The complaint alleges that despite this pre-suit knowledge, Defendants have continued to pursue FDA approval with the intent to market their product, allegedly without a reasonable basis for believing they would not be liable for infringement (Compl. ¶41, ¶43).

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

  1. A core issue will be one of litigation focus: Given the complaint’s assertion that Defendants did not contest infringement of Claim 1 in their notice letters, the case may pivot away from a technical infringement analysis and focus almost entirely on the validity and enforceability defenses raised in Defendants’ Paragraph IV certification.
  2. A key legal and technical question will be one of polymorphic scope: If infringement is contested, the dispute will likely center on whether the specific physical form of sitagliptin phosphate in the accused generic product falls within the scope of the asserted claims. This will raise the question of whether "a hydrate thereof" should be construed broadly to cover any hydrated form or be limited by the specification's detailed disclosure of a specific crystalline monohydrate.