Eli Lilly & Co v. MSN Laboratories Pvt Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Eli Lilly & Company (Indiana)
  • Defendant: MSN Laboratories Private Limited (India) and MSN Pharmaceuticals Inc. (Delaware)
  • Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP
• Case Identification: 1:26-cv-00985, D. Del., 08/06/2026
• Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendant MSN Pharmaceuticals Inc. is a Delaware corporation, and Defendant MSN Laboratories Private Limited is a foreign corporation that may be sued in any judicial district.
• Core Dispute: Plaintiff alleges that Defendants' Abbreviated New Drug Applications (ANDAs) to market generic versions of Plaintiff's Mounjaro® and Zepbound® (tirzepatide) products constitute an act of infringement of ten U.S. patents covering the tirzepatide compound, its formulation, and methods of use.
• Technical Context: The technology relates to GIP/GLP-1 co-agonist peptide therapeutics, a class of drugs that has proven highly effective for treating type 2 diabetes and promoting weight loss.
• Key Procedural History: This action was initiated under the Hatch-Waxman Act following Defendants' submission of ANDA Nos. 221718 and 221719 to the U.S. Food and Drug Administration (FDA). The ANDAs included Paragraph IV certifications asserting that the ten patents-in-suit are invalid, unenforceable, and/or will not be infringed by Defendants' proposed generic products. Plaintiff filed this complaint within the 45-day statutory window, triggering an automatic 30-month stay on the FDA’s approval of Defendants' ANDAs.

Case Timeline

Date	Event
2014-01-09	U.S. Patent No. 9,474,780 Priority Date
2016-10-25	U.S. Patent No. 9,474,780 Issue Date
2018-06-22	U.S. Patent Nos. 11,357,820; 11,918,623; 12,453,755; 12,453,756; and 12,629,404 Priority Date
2018-07-23	U.S. Patent Nos. 12,295,987; 12,343,382; 12,453,758; and 12,616,740 Priority Date
2022-05-13	FDA grants approval for Mounjaro® (tirzepatide)
2022-06-14	U.S. Patent No. 11,357,820 Issue Date
2023-11-08	FDA grants approval for Zepbound® (tirzepatide)
2024-03-05	U.S. Patent No. 11,918,623 Issue Date
2025-05-13	U.S. Patent No. 12,295,987 Issue Date
2025-07-01	U.S. Patent No. 12,343,382 Issue Date
2025-10-28	U.S. Patent Nos. 12,453,755; 12,453,756; and 12,453,758 Issue Date
2026-05-05	U.S. Patent No. 12,616,740 Issue Date
2026-05-19	U.S. Patent No. 12,629,404 Issue Date
2026-07-15	Defendants send ANDA Notice Letters to Plaintiff
2026-07-16	Plaintiff receives ANDA Notice Letters
2026-08-06	Complaint Filing Date

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

U.S. Patent No. 9,474,780 - “GIP and GLP-1 Co-agonist Compounds”

• Patent Identification: U.S. Patent No. 9,474,780, “GIP and GLP-1 Co-agonist Compounds,” issued October 25, 2016 (Compl. ¶26).

The Invention Explained

• Problem Addressed: The patent addresses the need for more effective treatments for type 2 diabetes mellitus (T2D) that can provide better glycemic control and potentially weight loss, overcoming the limitations and side effects of existing single-mechanism therapies (’780 Patent, col. 1:10-20).
• The Patented Solution: The patent discloses novel peptide compounds that act as dual agonists for both the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors (Compl. ¶22). One of these compounds is tirzepatide. The peptide backbone is chemically modified with a fatty acid moiety, which extends its half-life and allows for less frequent, such as once-weekly, administration (Compl. ¶56).
• Technical Importance: This dual-agonist approach combines the therapeutic effects of two key incretin hormones into a single molecule, offering a potentially more potent mechanism for managing T2D and obesity than single-agonist therapies.

Key Claims at a Glance

• The complaint asserts at least independent claim 1 (Compl. ¶56).
• The essential elements of independent claim 1 are:
  • A compound of Formula: YX₁EGTFTSDYSIX₂LDKIAQKAX₃VQWLIAGGPSSGAPPPS;
  • wherein X₁ is Aib; X₂ is Aib;
  • K at position 20 is chemically modified through conjugation to the epsilon-amino group of the K side-chain with ([2-(2-Amino-ethoxy)-ethoxy]-acetyl)₂(γGlu)ₐ-CO—(CH₂)b—CO₂H wherein a is 1 to 2 and b is 10 to 20;
  • X₃ is Phe or 1-Nal;
  • the C-terminal amino acid is optionally amidated as a C-terminal primary amide (SEQ ID NO: 11);
  • or a pharmaceutically acceptable salt thereof.
• The complaint alleges infringement of "one or more claims," which may suggest the intent to assert dependent claims later (Compl. ¶57).

U.S. Patent No. 11,357,820 - “GIP/GLP1 Agonist Compositions”

• Patent Identification: U.S. Patent No. 11,357,820, “GIP/GLP1 Agonist Compositions,” issued June 14, 2022 (Compl. ¶28).

The Invention Explained

• Problem Addressed: The patent describes the need for a commercially viable pharmaceutical composition of tirzepatide that provides acceptable shelf-life and in-use stability while also ensuring an acceptable patient experience upon subcutaneous injection, such as minimizing pain or stinging (’820 Patent, col. 1:23-28; col. 3:5-13).
• The Patented Solution: The patent discloses a specific formulation for tirzepatide that comprises the active ingredient, sodium chloride (NaCl) as a tonicity agent, and dibasic sodium phosphate as a buffering agent (’820 Patent, abstract). This particular combination of excipients is described as providing the desired stability and patient tolerability (’820 Patent, col. 3:45-53).
• Technical Importance: Creating a stable, well-tolerated injectable formulation is a critical step in developing a successful drug for chronic use, as it directly impacts patient compliance and the product's commercial lifespan.

Key Claims at a Glance

• The complaint asserts at least independent claim 1 (Compl. ¶73).
• The essential elements of independent claim 1 are:
  • A pharmaceutical composition comprising tirzepatide, or a pharmaceutically acceptable salt thereof;
  • NaCl at a concentration from 6.2 mg/mL to 9.5 mg/mL; and
  • dibasic sodium phosphate.
• The complaint alleges infringement of "one or more claims," reserving the right to assert additional claims (Compl. ¶74).

U.S. Patent No. 11,918,623 - “GIP/GLP1 Agonist Compositions”

• Patent Identification: U.S. Patent No. 11,918,623, "GIP/GLP1 Agonist Compositions," issued March 5, 2024 (Compl. ¶30).
• Technology Synopsis: This patent covers a method of treating obesity by administering a pharmaceutical composition containing tirzepatide within specific concentration ranges, along with defined amounts of dibasic sodium phosphate, NaCl, and optional phenol. The invention focuses on a specific formulation and its use in obesity treatment (Compl. ¶90).
• Asserted Claims: At least independent claim 1 is asserted (Compl. ¶90).
• Accused Features: Defendants are accused of infringement through their ANDA filing for a generic Zepbound® product and the proposed labeling that instructs and encourages the treatment of obesity using a composition that allegedly meets the claim's limitations (Compl. ¶88; Compl. ¶91).

U.S. Patent No. 12,295,987 - “Methods of Using a GIP/GLP1 Co-agonist for Diabetes”

• Patent Identification: U.S. Patent No. 12,295,987, "Methods of Using a GIP/GLP1 Co-agonist for Diabetes," issued May 13, 2025 (Compl. ¶32).
• Technology Synopsis: This patent claims a method of treating type 2 diabetes using a specific dose-escalation regimen. The method involves administering four escalating doses of a GIP:GLP-1 peptide (like tirzepatide) with a specific potency ratio, where the first, second, and third doses are defined as percentages of the fourth dose (Compl. ¶109).
• Asserted Claims: At least independent claim 1 is asserted (Compl. ¶109).
• Accused Features: Defendants' proposed labeling for their generic Mounjaro® product allegedly instructs and encourages treating type 2 diabetes using the claimed dose-escalation method (Compl. ¶110).

U.S. Patent No. 12,343,382 - “Methods of Using a GIP/GLP1 Co-agonist for Therapy”

• Patent Identification: U.S. Patent No. 12,343,382, "Methods of Using a GIP/GLP1 Co-agonist for Therapy," issued July 1, 2025 (Compl. ¶34).
• Technology Synopsis: This patent covers methods for treating type 2 diabetes (claim 1) and improving weight management (claim 11) using a specific dose-escalation and maintenance regimen for tirzepatide. The method requires administering weekly "escalation doses" from a specific group of dosages, followed by administering "maintenance doses" from another specific group of dosages (Compl. ¶128; Compl. ¶130).
• Asserted Claims: At least independent claims 1 and 11 are asserted (Compl. ¶¶128-131).
• Accused Features: The proposed labeling for Defendants' generic products allegedly instructs users on the claimed dosing regimen for treating type 2 diabetes and for weight management (Compl. ¶129; Compl. ¶131).

U.S. Patent No. 12,453,755 - “GIP/GLP1 Agonist Compositions”

• Patent Identification: U.S. Patent No. 12,453,755, "GIP/GLP1 Agonist Compositions," issued October 28, 2025 (Compl. ¶36).
• Technology Synopsis: This patent is directed to a method of treating diabetes by administering a specific pharmaceutical composition of tirzepatide. The composition is defined by concentration ranges for tirzepatide, dibasic sodium phosphate, NaCl, and optional phenol (Compl. ¶151).
• Asserted Claims: At least independent claim 1 is asserted (Compl. ¶151).
• Accused Features: Defendants are accused of infringement via their ANDA filing for a generic Mounjaro® product and the proposed labeling that instructs the use of a composition allegedly falling within the claimed parameters to treat diabetes (Compl. ¶149; Compl. ¶152).

U.S. Patent No. 12,453,756 - “GIP/GLP1 Agonist Compositions”

• Patent Identification: U.S. Patent No. 12,453,756, "GIP/GLP1 Agonist Compositions," issued October 28, 2025 (Compl. ¶38).
• Technology Synopsis: This patent claims a pharmaceutical composition of tirzepatide defined by a specific concentration range for NaCl and a specific pH range. The invention relates to a particular stable formulation of the drug (Compl. ¶170).
• Asserted Claims: At least independent claim 1 is asserted (Compl. ¶170).
• Accused Features: Defendants' Proposed ANDA Products are alleged to be pharmaceutical compositions that meet the limitations of the asserted claims, including the specified NaCl concentration and pH range (Compl. ¶171).

U.S. Patent No. 12,453,758 - “Methods of Using a GIP/GLP1 Co-agonist for Diabetes”

• Patent Identification: U.S. Patent No. 12,453,758, "Methods of Using a GIP/GLP1 Co-agonist for Diabetes," issued October 28, 2025 (Compl. ¶40).
• Technology Synopsis: This patent claims a method of improving weight management using a specific dose-escalation regimen for a GIP:GLP-1 peptide. The method involves four escalating doses defined by their potency ratio and relative percentage of the fourth dose (Compl. ¶187).
• Asserted Claims: At least independent claim 1 is asserted (Compl. ¶187).
• Accused Features: The proposed labeling for Defendants' generic Zepbound® product allegedly instructs and encourages the claimed dose-escalation method for weight management (Compl. ¶188).

U.S. Patent No. 12,616,740 - “Methods of Using a GIP/GLP1 Co-agonist for Therapy”

• Patent Identification: U.S. Patent No. 12,616,740, "Methods of Using a GIP/GLP1 Co-agonist for Therapy," issued May 5, 2026 (Compl. ¶42).
• Technology Synopsis: This patent covers methods of treating type 2 diabetes (claim 1) and obesity (claim 6) by administering tirzepatide in a specific once-weekly dose-escalation regimen. The regimen involves a 2.5 mg starting dose for four weeks, followed by 2.5 mg incremental increases to reach a maintenance dose of 5, 10, or 15 mg (Compl. ¶206; Compl. ¶208).
• Asserted Claims: At least independent claims 1 and 6 are asserted (Compl. ¶¶206-209).
• Accused Features: The proposed labeling for Defendants' generic products allegedly instructs users on the claimed dose-escalation regimen for treating both type 2 diabetes and obesity (Compl. ¶207; Compl. ¶209).

U.S. Patent No. 12,629,404 - “GIP/GLP1 Agonist Compositions”

• Patent Identification: U.S. Patent No. 12,629,404, "GIP/GLP1 Agonist Compositions," issued May 19, 2026 (Compl. ¶44).
• Technology Synopsis: This patent claims a specific "preservative-free" pharmaceutical composition of tirzepatide, defined by a concentration range for NaCl and a specific pH range (Compl. ¶229).
• Asserted Claims: At least independent claim 1 is asserted (Compl. ¶229).
• Accused Features: Defendants' Proposed ANDA Products are alleged to be preservative-free compositions that meet the claimed NaCl concentration and pH limitations (Compl. ¶230).

III. The Accused Instrumentality

• Product Identification: The accused instrumentalities are Defendants' "Proposed ANDA Products" corresponding to ANDA Nos. 221718 and 221719 (Compl. ¶1). These are proposed generic versions of Lilly’s Mounjaro® and Zepbound® products (Compl. ¶1).
• Functionality and Market Context:
  • The Proposed ANDA Products contain tirzepatide as the active pharmaceutical ingredient (Compl. ¶50). Tirzepatide is a GIP and GLP-1 receptor co-agonist used to improve glycemic control in patients with T2D and for chronic weight management (Compl. ¶1; Compl. ¶22).
  • Defendants' ANDAs seek approval to market various strengths of tirzepatide in vials and autoinjectors (Compl. ¶1; Compl. ¶9). The complaint alleges that the ANDAs rely on Lilly’s approved New Drug Applications (NDAs) for Mounjaro® and Zepbound® and contain data intended to demonstrate bioequivalence (Compl. ¶51).
  • The complaint alleges that upon FDA approval, Defendants intend to market these products as direct competitors to Mounjaro® and Zepbound® for the same indications prior to the expiration of the Asserted Patents (Compl. ¶1; Compl. ¶64).

IV. Analysis of Infringement Allegations

'780 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A compound of Formula: YX₁EGTFTSDYSIX₂LDKIAQKAX₃VQWLIAGGPSSGAPPPS; wherein X₁ is Aib; X₂ is Aib; K at position 20 is chemically modified through conjugation to the epsilon-amino group of the K side-chain with ([2-(2-Amino-ethoxy)-ethoxy]-acetyl)₂(yGlu)ₐ-CO—(CH₂)b—CO₂H wherein a is 1 to 2 and b is 10 to 20; X₃ is Phe or 1-Nal; and the C-terminal amino acid is optionally amidated as a C-terminal primary amide (SEQ ID NO: 11), or a pharmaceutically acceptable salt thereof.	The complaint alleges that Defendants' Proposed ANDA Products contain tirzepatide, which is a compound having the structural formula corresponding to the claim. The complaint provides a visual of the chemical structure of tirzepatide. (This visual is provided in the complaint and depicts the specific chemical structure of tirzepatide, aligning with the formula recited in the claim.)	¶57	col. 29:10-22

'820 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A pharmaceutical composition comprising tirzepatide, or a pharmaceutically acceptable salt thereof;	The complaint alleges that Defendants' Proposed ANDA Products are pharmaceutical compositions that comprise tirzepatide.	¶74	col. 9:40-42
NaCl at a concentration from 6.2 mg/mL to 9.5 mg/mL;	The complaint alleges the Proposed ANDA Products comprise NaCl at a concentration within the claimed range.	¶74	col. 9:43-44
and dibasic sodium phosphate.	The complaint alleges the Proposed ANDA Products comprise dibasic sodium phosphate.	¶74	col. 9:45-46

• Identified Points of Contention:
  • Scope Questions: For the numerous method-of-use patents (e.g., ’987, ’382, ’755, ’758, ’740), a central question will be whether the language in Defendants' proposed product labels is sufficient to prove inducement of infringement. The analysis will focus on whether the instructions and encouragements in the label direct medical professionals and patients to perform the patented methods. For the composition patents (e.g., ’780, ’820, ’756, ’404), the dispute will concern whether Defendants' proposed generic products, as defined in their ANDA submissions, meet all limitations of the asserted claims.
  • Technical Questions: A key technical question for the formulation patents ('820, '623, '755, '756, '404) will be whether Defendants' specific combination of excipients and their concentrations, pH, and preservative status literally infringes the asserted claims or infringes under the doctrine of equivalents. For the compound patent ('780), the primary technical question is simply whether the active ingredient in the ANDA products is, in fact, the claimed tirzepatide compound.

V. Key Claim Terms for Construction

The complaint does not provide sufficient detail for analysis of specific claim term disputes, which is common in ANDA litigation at the pleading stage. However, based on the nature of the asserted patents, certain terms may become central to the case.

• The Term: "dibasic sodium phosphate" (from claim 1 of the ’820 Patent)
• Context and Importance: This term is a required excipient in several of the asserted formulation patents (Compl. ¶73). Practitioners may focus on this term because the specific form of the salt (e.g., anhydrous, heptahydrate) used in the accused product could determine literal infringement. If Defendants use a form of dibasic sodium phosphate different from what is described or exemplified in the patent, it could create a non-infringement argument.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language itself simply recites "dibasic sodium phosphate" without specifying a hydration state or particular crystalline form (’820 Patent, col. 9:46). This lack of specificity may support a construction that is not limited to any particular form.
  • Evidence for a Narrower Interpretation: The patent’s specification, in its exemplary formulations, may disclose a specific form. For example, the patent discloses the use of "dibasic sodium phosphate*," where the asterisk indicates a 5 mM phosphate buffer is used, and elsewhere discloses "Sodium phosphate dibasic 7H₂O" ('820 Patent, Table 1, Table 3). A defendant may argue that the claims should be limited to the specific embodiments disclosed in the specification.

VI. Other Allegations

• Indirect Infringement: The complaint alleges both induced and contributory infringement for all ten asserted patents. The inducement allegations are based on the assertion that Defendants' proposed product labeling will instruct and encourage healthcare providers and patients to use the generic products in an infringing manner (e.g., Compl. ¶¶66, 83, 100, 119). The contributory infringement allegations are based on the assertion that Defendants' products are especially made for infringing uses and are not suitable for substantial non-infringing uses (e.g., Compl. ¶¶67, 84, 103, 122).
• Willful Infringement: The complaint does not use the term "willful." However, it repeatedly alleges that Defendants had knowledge of the Asserted Patents prior to litigation, at least because the patents are listed in the FDA's Orange Book and were included in Defendants' Paragraph IV Notice Letters (e.g., Compl. ¶¶65, 82, 99, 118). These allegations may form the basis for a later claim of willful infringement.

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

This case presents a large-scale Hatch-Waxman challenge to a major pharmaceutical product portfolio. The litigation will likely center on the following key questions for the court:

• A primary issue will be one of validity: can Defendants meet their burden of proving by clear and convincing evidence that the claims of Lilly's ten asserted patents are invalid for reasons such as obviousness, lack of written description, or anticipation, as asserted in their Paragraph IV certifications?
• A second core issue will be one of infringement scope, particularly for the numerous method-of-use and formulation patents. For the method claims, the question is whether the instructions in Defendants' proposed product labels are specific enough to induce infringement of the claimed dosing regimens. For the formulation claims, the question is whether the precise composition of Defendants' generic products, once revealed, will fall within the scope of Lilly's patent claims, potentially turning on the construction of terms like "dibasic sodium phosphate" and specified concentration ranges.