DCT

1:26-cv-00972

Eli Lilly & Co v. Alembic Pharma Ltd

Log In
Key Events
Complaint
complaint Intelligence

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:26-cv-00972, D. Del., 08/06/2026
  • Venue Allegations: Plaintiff alleges venue is proper for Alembic Pharmaceuticals Limited as a foreign corporation that may be sued in any judicial district, and for Alembic Pharmaceuticals, Inc. as a Delaware corporation that resides in the district for purposes of venue.
  • 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 nine U.S. patents covering tirzepatide compositions and methods of use.
  • Technical Context: The technology involves pharmaceutical formulations and treatment methods for tirzepatide, a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist used for glycemic control in type 2 diabetes and for chronic weight management.
  • Key Procedural History: This is a Hatch-Waxman action filed in response to Defendants' submission of ANDA Nos. 221547 and 221542 to the U.S. Food and Drug Administration (FDA). The lawsuit was triggered by Defendants' Notice Letters, dated July 10, 2026, which included Paragraph IV certifications asserting that the patents-in-suit are invalid, unenforceable, or will not be infringed by the proposed generic products.

Case Timeline

Date Event
2018-06-22 Earliest Priority Date for '820, '623, '755, '756, and '404 Patents
2018-07-23 Earliest Priority Date for '987, '382, '758, and '740 Patents
2022-05-13 FDA grants approval for Mounjaro® (tirzepatide)
2022-06-14 U.S. Patent No. 11,357,820 Issues
2023-11-08 FDA grants approval for Zepbound® (tirzepatide)
2024-03-05 U.S. Patent No. 11,918,623 Issues
2025-05-13 U.S. Patent No. 12,295,987 Issues
2025-07-01 U.S. Patent No. 12,343,382 Issues
2025-10-28 U.S. Patent No. 12,453,755 Issues
2025-10-28 U.S. Patent No. 12,453,756 Issues
2025-10-28 U.S. Patent No. 12,453,758 Issues
2026-05-05 U.S. Patent No. 12,616,740 Issues
2026-05-19 U.S. Patent No. 12,629,404 Issues
2026-07-10 Defendants send Notice Letters to Plaintiff
2026-07-13 Plaintiff receives Defendants' Notice Letters
2026-08-06 Complaint Filed

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

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

  • Patent Identification: U.S. Patent No. 11,357,820 ("the '820 Patent"), titled "GIP/GLP1 Agonist Compositions," issued on June 14, 2022 (Compl. ¶26).

The Invention Explained

  • Problem Addressed: The patent background describes the need for pharmaceutical compositions of the GIP/GLP1 co-agonist peptide tirzepatide that have acceptable stability and are associated with an acceptable patient experience upon injection (Compl. ¶26; '820 Patent, col. 1:21-25).
  • The Patented Solution: The patent discloses a pharmaceutical composition comprising tirzepatide, sodium chloride (NaCl) as a tonicity agent, and dibasic sodium phosphate as a buffering agent ('820 Patent, col. 1:1-6). This specific formulation is described as providing "commercially acceptable shelf-life stability, in-use stability, and is associated with acceptable patient injection site experience" ('820 Patent, col. 1:4-6).
  • Technical Importance: Creating a stable, injectable formulation of a biologic drug that is well-tolerated by patients is critical for commercial success, patient compliance, and therapeutic efficacy ('820 Patent, abstract; '820 Patent, col. 1:21-25).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶55).
  • The essential elements of 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 reserves the right to assert other claims from the patent (Compl. ¶56).

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

  • Patent Identification: U.S. Patent No. 11,918,623 ("the '623 Patent"), titled "GIP/GLP1 Agonist Compositions," issued on March 5, 2024 (Compl. ¶28).

The Invention Explained

  • Problem Addressed: The patent addresses the need for methods of treating obesity using a stable and well-tolerated formulation of tirzepatide ('623 Patent, col. 3:5-10; '623 Patent, col. 1:40-44).
  • The Patented Solution: The patent claims a method of treating obesity by administering an effective dose of a specific pharmaceutical composition. The composition comprises tirzepatide, dibasic sodium phosphate, and NaCl within specified concentration ranges, and optionally includes phenol ('623 Patent, claim 1). This combines a specific therapeutic use (treating obesity) with a specific formulation.
  • Technical Importance: This invention protects a specific method of using a particular formulation of tirzepatide for the indication of obesity, a significant and distinct market for this class of drugs ('623 Patent, abstract; Compl. ¶21).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶71).
  • The essential elements of Claim 1 are:
    • A method of treating obesity comprising administering to a human in need thereof an effective dose of a pharmaceutical composition comprising tirzepatide, or pharmaceutically acceptable salt thereof,
    • wherein the tirzepatide concentration is from about 5 mg/mL to about 30 mg/mL;
    • dibasic sodium phosphate is from about 0.67 to about 2.68 mg/mL;
    • NaCl at a concentration from about 6.2 mg/mL to about 9.5 mg/mL;
    • and optionally comprising from about 3.0 mg/mL to about 7.0 mg/mL phenol.
  • The complaint reserves the right to assert other claims (Compl. ¶72).

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 ("the '987 Patent"), titled "Methods of Using a GIP/GLP1 Co-agonist for Diabetes," issued on May 13, 2025 (Compl. ¶30).

The Invention Explained

  • The patent claims a method of treating type 2 diabetes using a specific dose-escalation regimen. The method involves administering four doses of a GIP:GLP-1 peptide, where the first, second, and third doses are specific percentages (25%, 50%, and 75%) of the fourth dose (Compl. ¶89).

Key Claims at a Glance

  • At least independent claim 1 is asserted (Compl. ¶90).
  • The complaint alleges that Defendants' proposed labeling for their generic Mounjaro® product will instruct and encourage the practice of this specific dosing regimen (Compl. ¶90).

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 ("the '382 Patent"), titled "Methods of Using a GIP/GLP1 Co-agonist for Therapy," issued on July 1, 2025 (Compl. ¶32).

The Invention Explained

  • The patent claims a method of treating type 2 diabetes or improving weight management using a dose-escalation and maintenance schedule. The method requires administering specific escalation doses (e.g., 2.5 mg, 7.5 mg, 12.5 mg) followed by specific maintenance doses (e.g., 5.0 mg, 10.0 mg, 15.0 mg) (Compl. ¶¶107, 109).

Key Claims at a Glance

  • At least independent claims 1 and 11 are asserted (Compl. ¶¶108, 110).
  • The complaint alleges that Defendants' proposed labeling will instruct and encourage the use of the claimed escalation and maintenance dosing schedules for treating diabetes and improving weight management (Compl. ¶¶108, 110).

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

  • Patent Identification: U.S. Patent No. 12,453,755 ("the '755 Patent"), titled "GIP/GLP1 Agonist Compositions," issued on October 28, 2025 (Compl. ¶34).

The Invention Explained

  • The patent claims a method of treating diabetes by administering a pharmaceutical composition with specific concentration ranges for tirzepatide, dibasic sodium phosphate, NaCl, and optional phenol. The claimed formulation is very similar to that in the '623 Patent (Compl. ¶130).

Key Claims at a Glance

  • At least independent claim 1 is asserted (Compl. ¶131).
  • The complaint alleges Defendants' proposed labeling will instruct treating diabetes by administering a composition that matches the claimed formulation (Compl. ¶131).

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

  • Patent Identification: U.S. Patent No. 12,453,756 ("the '756 Patent"), titled "GIP/GLP1 Agonist Compositions," issued on October 28, 2025 (Compl. ¶36).

The Invention Explained

  • The patent claims a pharmaceutical composition comprising tirzepatide and a specific concentration range of NaCl, where the composition has a pH between 6.5 and 7.5 (Compl. ¶148).

Key Claims at a Glance

  • At least independent claim 1 is asserted (Compl. ¶149).
  • The complaint alleges Defendants' Proposed ANDA Products are pharmaceutical compositions that meet the claimed parameters (Compl. ¶149).

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 ("the '758 Patent"), titled "Methods of Using a GIP/GLP1 Co-agonist for Diabetes," issued on October 28, 2025 (Compl. ¶38).

The Invention Explained

  • The patent claims a method of improving weight management using a specific four-step dose escalation regimen (25%, 50%, 75% of the fourth dose) with a GIP:GLP-1 peptide having a specific potency ratio (Compl. ¶165).

Key Claims at a Glance

  • At least independent claim 1 is asserted (Compl. ¶166).
  • The complaint alleges Defendants' proposed labeling for their generic Zepbound® product will instruct and encourage the practice of this specific dosing regimen (Compl. ¶166).

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 ("the '740 Patent"), titled "Methods of Using a GIP/GLP1 Co-agonist for Therapy," issued on May 5, 2026 (Compl. ¶40).

The Invention Explained

  • The patent claims a method for treating type 2 diabetes or obesity by administering tirzepatide in a specific dose-escalation regimen: starting at 2.5 mg once-weekly for four weeks, then increasing by 2.5 mg increments to a maintenance dose of 5, 10, or 15 mg (Compl. ¶¶183, 185).

Key Claims at a Glance

  • At least independent claims 1 and 6 are asserted (Compl. ¶¶184, 186).
  • The complaint alleges Defendants' proposed labeling will instruct and encourage the use of this specific dosing regimen (Compl. ¶¶184, 186).

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

  • Patent Identification: U.S. Patent No. 12,629,404 ("the '404 Patent"), titled "GIP/GLP1 Agonist Compositions," issued on May 19, 2026 (Compl. ¶42).

The Invention Explained

  • The patent claims a pharmaceutical composition that is "free of preservative" and comprises tirzepatide, a specific concentration of NaCl, and has a specific pH range (Compl. ¶206).

Key Claims at a Glance

  • At least independent claim 1 is asserted (Compl. ¶207).
  • The complaint alleges Defendants' Proposed ANDA Products are compositions that meet the claimed parameters, including being free of preservative (Compl. ¶207).

III. The Accused Instrumentality

Product Identification

  • Defendants' proposed generic versions of Mounjaro® and Zepbound® autoinjectors, filed under ANDA Nos. 221547 and 221542 (collectively, the "Proposed ANDA Products") (Compl. ¶1).

Functionality and Market Context

  • The Proposed ANDA Products are sterile, injectable solutions containing the active pharmaceutical ingredient tirzepatide, a GIP/GLP-1 receptor agonist (Compl. ¶22; Compl. ¶23). They are intended for subcutaneous administration in various strengths (2.5 mg/0.5 mL to 15 mg/0.5 mL) (Compl. ¶1). The complaint alleges these products are intended for use as an adjunct to diet and exercise to improve glycemic control in adults and certain pediatric patients with type 2 diabetes mellitus, and for chronic weight management in adults with obesity or overweight with at least one weight-related comorbid condition (Compl. ¶1; Compl. ¶2). These uses correspond to the FDA-approved indications for Lilly's Mounjaro® and Zepbound® products (Compl. ¶¶20-21).

No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

'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 Proposed ANDA Products are pharmaceutical compositions that comprise tirzepatide. ¶56 col. 2:5-11
NaCl at a concentration from 6.2 mg/mL to 9.5 mg/mL; The Proposed ANDA Products are alleged to contain NaCl at a concentration within the claimed range. ¶56 col. 1:32-33
and dibasic sodium phosphate. The Proposed ANDA Products are alleged to contain dibasic sodium phosphate or an equivalent thereof. ¶56 col. 1:3-6

Identified Points of Contention

  • Scope Questions: The complaint alleges infringement via "dibasic sodium phosphate or equivalent thereof" (Compl. ¶56). A potential point of contention is whether Defendants' formulation uses an agent that is not dibasic sodium phosphate and, if so, whether that agent can be considered an "equivalent" under the doctrine of equivalents. The analysis will depend on the function, way, and result of the alternative agent compared to the claimed one.
  • Technical Questions: Infringement will depend on whether the precise concentration of NaCl in Defendants' final marketed products falls within the claimed "6.2 mg/mL to 9.5 mg/mL" range.

'623 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A method of treating obesity comprising administering to a human in need thereof an effective dose of a pharmaceutical composition comprising tirzepatide, or pharmaceutically acceptable salt thereof, The complaint alleges Defendants' proposed product labeling will instruct and encourage the administration of the Proposed ANDA No. 221542 Product for the purpose of treating obesity. ¶72 col. 3:5-10
wherein the tirzepatide concentration is from about 5 mg/mL to about 30 mg/mL; The Proposed ANDA No. 221542 Product is alleged to be a composition with a tirzepatide concentration within this claimed range. ¶72 col. 10:45-47
dibasic sodium phosphate is from about 0.67 to about 2.68 mg/mL; The Proposed ANDA No. 221542 Product is alleged to contain dibasic sodium phosphate at a concentration within this claimed range. ¶72 col. 10:47-49
NaCl at a concentration from about 6.2 mg/mL to about 9.5 mg/mL; The Proposed ANDA No. 221542 Product is alleged to contain NaCl at a concentration within this claimed range. ¶72 col. 10:49-50
and optionally comprising from about 3.0 mg/mL to about 7.0 mg/mL phenol. The Proposed ANDA No. 221542 Product is alleged to optionally contain phenol within this claimed range. ¶72 col. 10:50-52

Identified Points of Contention

  • Scope Questions: The claims recite concentrations preceded by "about." The construction of "about" will be critical in determining whether Defendants' formulation, even if slightly outside the specified numerical endpoints, still falls within the scope of the claims.
  • Evidentiary Questions: As this is a method-of-use claim, infringement hinges on induced infringement. A key question will be whether the specific language in Defendants' proposed product labeling for their generic Zepbound® product instructs users to administer the product in a way that meets all limitations of the claimed method.

V. Key Claim Terms for Construction

The Term: "dibasic sodium phosphate" ('820 Patent, Claim 1)

  • Context and Importance: This term is critical because the complaint alleges the Proposed ANDA Products contain "dibasic sodium phosphate or equivalent thereof" (Compl. ¶56), suggesting a potential dispute over literal infringement versus infringement under the doctrine of equivalents. The definition will determine whether an alternative buffering agent used by the Defendants could fall within the claim's scope.

Intrinsic Evidence for Interpretation

  • Evidence for a Broader Interpretation: The specification describes the invention as comprising tirzepatide, an agent like NaCl, and "dibasic sodium phosphate," and notes the pH is adjusted using "physiologically appropriate acids and bases" ('820 Patent, col. 1:30-31; '820 Patent, col. 4:18-22). This may support an argument that the specific identity of the phosphate buffer is less important than its function in maintaining pH.
  • Evidence for a Narrower Interpretation: Claim 1 explicitly recites "dibasic sodium phosphate" without broader language like "a phosphate buffer" ('820 Patent, col. 10:1-3). This specificity may support an argument that the claim is limited to the exact chemical entity named and does not cover other phosphate salts or buffering systems.

The Term: "about" ('623 Patent, Claim 1)

  • Context and Importance: This term modifies all concentration ranges in the asserted method claim. Its construction will determine the permissible deviation from the recited numerical values. Practitioners may focus on this term because the infringement analysis will depend on whether the precise concentrations in Defendants' product are captured by the claimed ranges, even if not identical.

Intrinsic Evidence for Interpretation

  • Evidence for a Broader Interpretation: The term "about" is used consistently before numerical values in the claims and specification, suggesting the patentee intended to claim a range of values and not be strictly limited to the recited numbers, accounting for standard manufacturing and measurement tolerances ('623 Patent, claim 1; '623 Patent, col. 2:1-10).
  • Evidence for a Narrower Interpretation: The patent provides tables with specific, precise concentration values for exemplary formulations (e.g., NaCl at "8.8" mg/mL) ('623 Patent, Table 5). This may support an argument that "about" should be construed narrowly to encompass only minor, insignificant variations from these disclosed examples.

VI. Other Allegations

Indirect Infringement

  • The complaint alleges active inducement of infringement for the method patents. The basis for this allegation is that Defendants' proposed product labeling for their generic versions of Mounjaro® and Zepbound® will instruct and encourage healthcare providers and patients to administer the products in accordance with the patented methods of treatment and dosing regimens (Compl. ¶¶80-82; Compl. ¶¶98-100). Contributory infringement is also alleged on the basis that the Proposed ANDA Products are especially made or adapted for use in the patented methods and are not suitable for substantial non-infringing use (Compl. ¶65; Compl. ¶83).

Willful Infringement

  • While not pleaded as a separate count, the complaint lays a foundation for willfulness by alleging Defendants had pre-suit knowledge of the asserted patents. This knowledge is alleged to arise from the patents' listing in the FDA's Orange Book for Mounjaro® and Zepbound®, as well as from Defendants' inclusion of the patents in their Paragraph IV Notice Letters (Compl. ¶63; Compl. ¶79). The complaint further alleges that despite this knowledge, Defendants intend to engage in infringing activities immediately upon FDA approval (Compl. ¶62; Compl. ¶78).

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

  • A central issue for the composition patents (e.g., '820, '756, '404) will be one of chemical and quantitative identity: do the specific formulations of Defendants' Proposed ANDA Products, including the exact concentrations of tirzepatide, NaCl, and buffering agents, fall within the literal scope of the claimed ranges, and if not, can they be considered equivalent?
  • For the method-of-use patents (e.g., '623, '987, '382, '740), a key evidentiary question will be one of induced infringement: does the language of Defendants' proposed product labeling actively instruct and encourage physicians and patients to administer the generic products according to the specific dose-escalation schedules, maintenance doses, and treatment indications claimed by Lilly?
  • Underpinning the entire dispute is the question of patent validity. The case will likely involve a significant focus on whether Defendants can prove, by clear and convincing evidence, that the asserted patent claims are invalid as obvious or anticipated by the prior art, an issue raised by Defendants' Paragraph IV certifications but not detailed in the complaint itself.
Loading Complaint