DCT
1:25-cv-00449
Merck Sharp & Dohme LLC v. Aurobindo Pharma Limited
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Merck Sharp & Dohme LLC (New Jersey)
- Defendant: Aurobindo Pharma Limited (India) and Aurobindo Pharma USA, Inc. (Delaware)
- Plaintiff’s Counsel: McCarter & English, LLP
- Case Identification: 1:25-cv-00449, D. Del., 04/11/2025
- Venue Allegations: Venue is based on Defendant Aurobindo Pharma USA, Inc. being a Delaware corporation with a registered agent in the state, and both defendants allegedly transacting business, developing, and planning to sell the accused product in Delaware.
- Core Dispute: Plaintiff alleges that Defendants' submission of an Abbreviated New Drug Application (ANDA) to the FDA 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 technology concerns a specific phosphate salt of sitagliptin, a dipeptidyl peptidase-IV (DPP-IV) inhibitor used for the treatment of Type 2 diabetes, a major pharmaceutical market.
- Key Procedural History: The complaint arises from Defendants' February 24, 2025 notice letter to Plaintiff, informing Plaintiff of its ANDA filing and its certification that the patent-in-suit is invalid, unenforceable, or not infringed. The patent-in-suit, U.S. Patent No. 7,326,708, was the subject of inter partes review (IPR) proceedings (IPR2020-00040, -01060, -01072), which concluded with a certificate issued September 19, 2023, confirming the patentability of asserted claims 1-4, among others.
Case Timeline
| Date | Event |
|---|---|
| 2003-06-24 | ’708 Patent Priority Date |
| 2008-02-05 | ’708 Patent Issue Date |
| 2023-09-19 | IPR Certificate issued, confirming patentability of claims 1-4 |
| 2025-02-24 | Aurobindo sends Notice Letter to Merck regarding ANDA submission |
| 2025-04-11 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,326,708 - "Phosphoric Acid Salt of a Dipeptidyl Peptidase-IV Inhibitor"
- Issued: February 5, 2008
The Invention Explained
- Problem Addressed: The patent addresses the need for improved forms of beta-amino tetrahydrotriazolo[4,3-a]pyrazines, which are known to be potent inhibitors of the DP-IV enzyme for the treatment of Type 2 diabetes (ʼ708 Patent, col. 1:31-56). While the base compound was known, developing a form with properties suitable for large-scale pharmaceutical manufacturing, such as improved stability and handling, presented a technical challenge ('708 Patent, col. 2:5-11).
- The Patented Solution: The invention is a specific salt of the active pharmaceutical ingredient: a "dihydrogenphosphate salt" of the compound 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, now commonly known as sitagliptin ('708 Patent, Abstract). The patent particularly describes a stable, crystalline monohydrate of this salt, which allegedly possesses advantageous physicochemical properties (e.g., solubility, stability to heat and humidity) that make it "particularly suitable for the manufacture of various pharmaceutical dosage forms" ('708 Patent, col. 2:11-18; col. 2:62-65).
- Technical Importance: Creating a stable, crystalline salt form of an active pharmaceutical ingredient is a critical step in drug development, as it directly impacts the drug's shelf-life, manufacturability, and consistency in solid oral dosage forms ('708 Patent, col. 2:5-18).
Key Claims at a Glance
- The complaint asserts "one or more claims of the ’708 patent, including at least claim 1" (Compl. ¶29).
- Independent Claim 1 recites:
- 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's phrasing suggests a reservation of the right to assert other claims, including dependent claims that further narrow the invention to specific stereoisomers or crystalline forms.
III. The Accused Instrumentality
Product Identification
- Defendants' proposed generic sitagliptin/metformin hydrochloride extended-release tablets, identified as "Aurobindo's ANDA Product" associated with ANDA No. 220279 (Compl. ¶1, 2). The product is a generic version of Plaintiff's JANUMET XR® tablets (Compl. ¶3).
Functionality and Market Context
- The accused product is a pharmaceutical composition intended for the treatment of Type 2 diabetes (Compl. ¶1; ’708 Patent, col. 1:36-40). The complaint alleges that Defendants' notice letter explicitly states that the ANDA Product "contains sitagliptin phosphate as an active ingredient" (Compl. ¶28). The act of infringement alleged is the submission of the ANDA itself, which seeks FDA approval to market this generic drug prior to the expiration of the ’708 patent (Compl. ¶1, 31).
IV. Analysis of Infringement Allegations
No probative visual evidence provided in complaint.
- Claim Chart Summary:
| 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 of structural formula I... | The complaint alleges that Defendants' notice letter stated that their ANDA Product "contains sitagliptin phosphate as an active ingredient," which is the dihydrogenphosphate salt of the chemical compound recited in the claim. | ¶28, ¶29 | col. 2:44-55 |
| ...or a hydrate thereof. | The allegation that the product contains "sitagliptin phosphate" is sufficient to read on the first clause of the claim, making this disjunctive element also potentially met. The patent describes a specific crystalline monohydrate of the claimed salt. | ¶28, ¶29 | col. 2:62-65 |
- Identified Points of Contention:
- Legal Questions: The complaint makes the significant allegation that "Aurobindo did not contest infringement of claim 1 of the '708 patent" in its notice letter (Compl. ¶30). If this is accurate, the primary legal dispute is unlikely to be infringement and will instead focus on the patent's validity and/or enforceability, which Defendants challenged in their Paragraph IV certification (Compl. ¶27).
- Technical Questions: A potential, though perhaps minor, point of contention could be one of characterization: what evidence demonstrates that the "sitagliptin phosphate" described in the ANDA is identical in structure and form to that required by the claims, particularly when read in light of the specification's detailed description of a specific crystalline monohydrate?
V. Key Claim Terms for Construction
Even with infringement allegedly uncontested, the construction of key terms remains foundational to the case.
The Term: "dihydrogenphosphate salt"
- Context and Importance: This term defines the precise chemical nature of the claimed compound. Practitioners may focus on this term because any subtle difference in the salt stoichiometry or structure in the accused product could form the basis of a non-infringement argument, should one be raised.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent claims the salt generally without limitation to a specific crystalline form ('708 Patent, cl. 1). The specification refers to it as a "monobasic dihydrogenphosphate salt," comprised of one molar equivalent of the protonated amine cation and one molar equivalent of the dihydrogenphosphate anion ('708 Patent, col. 3:47-53).
- Evidence for a Narrower Interpretation: The specification's only working examples and detailed characterization data (e.g., XRD, NMR, DSC) are for a specific "crystalline monohydrate" of the salt ('708 Patent, col. 13:21-50; FIGS. 1-5). A party could argue the claims should be limited to this well-defined and exemplified form.
The Term: "a hydrate thereof"
- Context and Importance: This alternative provides a second avenue for proving infringement. Its scope is critical: does it encompass any hydrated form of the salt or only the specific monohydrate disclosed in the patent?
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The plain language "a hydrate" is not explicitly limited and could be argued to cover various hydrated states.
- Evidence for a Narrower Interpretation: The patent's abstract and detailed description repeatedly identify the invention with a specific "crystalline monohydrate" ('708 Patent, Abstract; col. 2:62-65). This consistent focus could be used to argue that the inventors defined their invention as being limited to this specific form.
VI. Other Allegations
- Indirect Infringement: The complaint alleges active inducement of infringement, stating that Defendants intend for their ANDA Product to be used as directed by its proposed labeling, which will instruct physicians and patients to use the drug in a manner that infringes the ’708 patent (Compl. ¶34, 35). This is premised on Defendants' knowledge of the patent and intent to cause infringing acts upon FDA approval (Compl. ¶35).
- Willful Infringement: Willfulness is alleged based on Defendants' "full knowledge of the '708 patent" and proceeding with their intent to market the generic product despite this knowledge (Compl. ¶39). The factual basis for this knowledge is, at a minimum, the notice letter sent to Merck (Compl. ¶2, 26).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of patent validity. The complaint states that Defendants filed a Paragraph IV certification asserting the ’708 patent is invalid and/or unenforceable (Compl. ¶27), while allegedly not contesting infringement of Claim 1 (Compl. ¶30). The case will therefore likely center on whether Defendants can prove by clear and convincing evidence that the asserted claims are invalid, a question that must be considered in light of the patent having previously survived IPR proceedings that confirmed the patentability of the key claims.
- A key evidentiary question may be one of technical identity. Should a dispute arise, the focus will be on whether the specific polymorphic form of "sitagliptin phosphate" in Defendants' ANDA product is definitively shown to be the same chemical entity as the "dihydrogenphosphate salt" or "a hydrate thereof" as construed from the claims and specification of the ’708 patent.