DCT

1:26-cv-00974

Eli Lilly & Co v. Aspiro Pharma Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:26-cv-00974, D. Del., 08/13/2026
  • Venue Allegations: Venue is alleged to be proper as to Hetero USA, Inc. because it is a Delaware corporation. Venue is alleged to be proper as to Aspiro Pharma Limited and Hetero Labs Limited because they are foreign corporations that may be sued in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendants' submission of Abbreviated New Drug Applications (ANDAs) to the FDA for generic versions of Mounjaro® and Zepbound® constitutes an act of infringement of nine U.S. patents covering pharmaceutical compositions of the active ingredient tirzepatide and methods of its use.
  • Technical Context: The technology relates to formulations and dosing regimens for tirzepatide, a dual GIP/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' Paragraph IV certifications asserting that Plaintiff's Orange Book-listed patents are invalid, unenforceable, or will not be infringed by the proposed generic products. The complaint was filed within the 45-day statutory window following receipt of Defendants' notice letters, triggering a potential 30-month stay of FDA approval for the generic products.

Case Timeline

Date Event
2018-06-22 Earliest Priority Date ('820, '623, '755, '756, '404 Patents)
2018-07-23 Earliest Priority Date ('987, '382, '758, '740 Patents)
2022-05-13 FDA Approval of Mounjaro®
2022-06-14 Issue Date: U.S. Patent No. 11,357,820
2023-11-08 FDA Approval of Zepbound®
2024-03-05 Issue Date: U.S. Patent No. 11,918,623
2025-05-13 Issue Date: U.S. Patent No. 12,295,987
2025-07-01 Issue Date: U.S. Patent No. 12,343,382
2025-10-28 Issue Date: U.S. Patent Nos. 12,453,755; 12,453,756; 12,453,758
2026-05-05 Issue Date: U.S. Patent No. 12,616,740
2026-05-19 Issue Date: U.S. Patent No. 12,629,404
2026-07-15 Date of Defendants' ANDA Notice Letters
2026-07-16 Plaintiff's receipt of Defendants' Notice Letters
2026-08-13 Complaint Filing Date

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. 11357820, issued June 14, 2022 Compl. ¶30

The Invention Explained

  • Problem Addressed: The patent background indicates a need for pharmaceutical compositions of tirzepatide that provide "acceptable stability and acceptable patient injection site experience" '820 Patent, col. 3:24-27 This suggests that prior formulations may have been suboptimal in terms of shelf-life or patient comfort upon injection.
  • The Patented Solution: The invention is a specific pharmaceutical formulation that combines tirzepatide with sodium chloride (NaCl) and dibasic sodium phosphate as excipients '820 Patent, abstract This combination is described as providing both shelf-life stability and an acceptable patient injection experience, distinguishing it from compositions using other agents, like citrate, that have been associated with "painful stinging" '820 Patent, col. 4:8-13
  • Technical Importance: For chronically administered injectable drugs like tirzepatide, a formulation that minimizes injection site pain is critical for ensuring patient compliance and adherence to treatment regimens '820 Patent, col. 4:5-8

Key Claims at a Glance

  • The complaint asserts infringement of at least claim 1 Compl. ¶61
  • Independent claim 1 requires:
    • 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 '820 Patent, col. 9:40-44

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

  • Patent Identification: U.S. Patent No. 11918623, issued March 5, 2024 Compl. ¶32

The Invention Explained

  • Problem Addressed: The patent addresses the need for effective obesity treatments by leveraging the GIP/GLP1 co-agonist activity of tirzepatide '623 Patent, col. 3:3-7 The underlying technical challenge remains creating a stable and patient-acceptable formulation for this therapeutic use.
  • The Patented Solution: The patent claims a method of treating obesity by administering a specific pharmaceutical formulation of tirzepatide '623 Patent, abstract The formulation is defined by concentration ranges for the active ingredient (tirzepatide), a buffering agent (dibasic sodium phosphate), a tonicity agent (NaCl), and an optional preservative (phenol) '623 Patent, claim 1
  • Technical Importance: The patent seeks to protect a specific method of using a particular tirzepatide formulation for the commercially significant indication of obesity, creating a potential barrier for generic competitors targeting this market.

Key Claims at a Glance

  • The complaint asserts infringement of at least claim 1 Compl. ¶77
  • Independent claim 1 requires:
    • A method of treating obesity comprising administering to a human an effective dose of a pharmaceutical composition comprising tirzepatide;
    • 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 is 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 '623 Patent, claim 1

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

  • Patent Identification: U.S. Patent No. 12295987, issued May 13, 2025 Compl. ¶34
  • Technology Synopsis: The patent claims a method of treating type 2 diabetes using a specific four-step dose-escalation regimen. The method is defined by the relative potencies of the GIP:GLP-1 peptide and the percentage-based relationship between the four administered doses Compl. ¶95
  • Asserted Claims: At least claim 1 is asserted Compl. ¶96
  • Accused Features: Defendants' proposed labeling for their generic Mounjaro® product is alleged to instruct and encourage the claimed dosing regimen Compl. ¶96

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

  • Patent Identification: U.S. Patent No. 12343382, issued July 1, 2025 Compl. ¶36
  • Technology Synopsis: The patent claims methods for treating type 2 diabetes and for improving weight management. The methods comprise an "escalation dose" phase followed by a "maintenance dose" phase, with specific dose amounts defined for each phase Compl. ¶¶114, 116
  • Asserted Claims: At least claims 1 and 11 are asserted Compl. ¶118
  • Accused Features: Defendants' proposed labeling for their generic Mounjaro® product is alleged to instruct the method for treating type 2 diabetes, and the proposed labeling for their generic Zepbound® product is alleged to instruct the method for improving weight management Compl. ¶¶115, 117

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

  • Patent Identification: U.S. Patent No. 12453755, issued October 28, 2025 Compl. ¶38
  • Technology Synopsis: The patent claims a method of treating diabetes by administering a pharmaceutical composition of tirzepatide defined by specific concentration ranges for the active ingredient, dibasic sodium phosphate, NaCl, and optionally phenol Compl. ¶137
  • Asserted Claims: At least claim 1 is asserted Compl. ¶138
  • Accused Features: The proposed labeling for Defendants' generic Mounjaro® product is alleged to instruct and encourage the claimed method of treatment Compl. ¶138

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

  • Patent Identification: U.S. Patent No. 12453756, issued October 28, 2025 Compl. ¶40
  • Technology Synopsis: The patent claims a pharmaceutical composition of tirzepatide defined by a specific concentration range of NaCl and a specific pH range Compl. ¶156
  • Asserted Claims: At least claim 1 is asserted Compl. ¶157
  • Accused Features: The composition of Defendants' Proposed ANDA Products is alleged to infringe the claims Compl. ¶157

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

  • Patent Identification: U.S. Patent No. 12453758, issued October 28, 2025 Compl. ¶42
  • Technology Synopsis: The patent claims a method of improving weight management using a specific four-step dose-escalation regimen, defined by the peptide's relative potency and the percentage-based relationship between the doses Compl. ¶173
  • Asserted Claims: At least claim 1 is asserted Compl. ¶174
  • Accused Features: The proposed labeling for Defendants' generic Zepbound® product is alleged to instruct and encourage the claimed dosing regimen Compl. ¶174

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

  • Patent Identification: U.S. Patent No. 12616740, issued May 5, 2026 Compl. ¶44
  • Technology Synopsis: The patent claims methods for treating type 2 diabetes and obesity using a specific dose escalation schedule. The regimen involves a 2.5 mg starting dose, followed by 2.5 mg incremental increases to reach a maintenance dose of 5, 10, or 15 mg Compl. ¶¶192, 194
  • Asserted Claims: At least claims 1 and 6 are asserted Compl. ¶196
  • Accused Features: The proposed labeling for the generic Mounjaro® and Zepbound® products is alleged to instruct the claimed methods Compl. ¶¶193, 195

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

  • Patent Identification: U.S. Patent No. 12629404, issued May 19, 2026 Compl. ¶46
  • Technology Synopsis: The patent claims a preservative-free pharmaceutical composition of tirzepatide defined by a specific concentration range of NaCl and a specific pH range Compl. ¶215
  • Asserted Claims: At least claim 1 is asserted Compl. ¶216
  • Accused Features: The composition of Defendants' Proposed ANDA Products is alleged to infringe the claims Compl. ¶216

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are the "Proposed ANDA Products" for which Defendants seek FDA approval via ANDA Nos. 221575 and 221574 Compl. ¶1 These are generic versions of Lilly's Mounjaro® and Zepbound® (tirzepatide) products, formulated as autoinjectors in various strengths Compl. ¶1

Functionality and Market Context

The complaint alleges that the submission of the ANDAs is itself an act of infringement under 35 U.S.C. § 271(e)(2) Compl. ¶66 The technical functionality at issue is twofold: (1) the specific chemical composition of the proposed generic products, which is alleged to match the compositions claimed in certain asserted patents Compl. ¶60, and (2) the instructions for use in the proposed product labeling, which are alleged to encourage administration according to the methods claimed in other asserted patents Compl. ¶77 The complaint includes an image of an "Injectable facility" with an "Aspiro" logo to connect the defendants to the manufacture of such products Compl. ¶8 If approved, these products would compete directly with Lilly's Mounjaro® and Zepbound® for treating type 2 diabetes and obesity Compl. ¶1

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 complaint alleges that Defendants' Proposed ANDA Products are pharmaceutical compositions that comprise tirzepatide or a salt thereof. ¶60 col. 3:21-23
NaCl at a concentration from 6.2 mg/mL to 9.5 mg/mL; The complaint alleges the Proposed ANDA Products contain NaCl at a concentration within the claimed range. ¶60 col. 3:31-33
and dibasic sodium phosphate. The complaint alleges the Proposed ANDA Products contain dibasic sodium phosphate. ¶60 col. 3:41-42
  • Identified Points of Contention ('820 Patent):
    • Evidentiary Question: The core of the dispute for this patent will be factual. The complaint alleges the composition of the Proposed ANDA Products infringes, but this is based on "information and belief" Compl. ¶13 The central question is whether discovery will confirm that Defendants' proposed generic formulation contains the claimed ingredients at the claimed concentrations.
    • Scope Question: A potential point of contention may arise regarding the term "dibasic sodium phosphate." The claim does not specify a hydration state, which could lead to disputes over whether the term covers various salt forms (e.g., anhydrous vs. heptahydrate) and how concentration is measured if different forms are used.

'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 that Defendants are seeking approval for a proposed labeling that "instructs and encourages treating obesity by administering" the proposed product. ¶77 col. 4:51-54
wherein the tirzepatide concentration is from about 5 mg/mL to about 30 mg/mL; The complaint alleges the proposed product contains a tirzepatide concentration within this range. ¶77 col. 4:5-6
dibasic sodium phosphate is from about 0.67 to about 2.68 mg/mL; The complaint alleges the proposed product contains a dibasic sodium phosphate concentration within this range. ¶77 col. 4:11-12
NaCl at a concentration from about 6.2 mg/mL to about 9.5 mg/mL; The complaint alleges the proposed product contains an NaCl concentration within this range. ¶77 col. 4:2-4
and optionally comprising from about 3.0 mg/mL to about 7.0 mg/mL phenol. The complaint alleges the proposed product optionally contains phenol within this range. ¶77 col. 4:39-41
  • Identified Points of Contention ('623 Patent):
    • Labeling and Inducement: The central issue for this method-of-use patent will be whether Defendants' proposed product label will induce infringement. This raises the question of whether the label instructs, encourages, or suggests to physicians or patients that they should administer the drug in a manner that meets all the limitations of claim 1 for the purpose of "treating obesity."
    • "Carve-Out" Question: A related question is whether Defendants have attempted to "carve out" the patented method from their proposed label. The court may need to analyze if any such carve-out is sufficient to avoid inducement, or if the nature of the product and its other approved uses makes infringement inevitable.

V. Key Claim Terms for Construction

'820 Patent, Claim 1

  • The Term: "dibasic sodium phosphate"
  • Context and Importance: This term identifies a key excipient. The patent claims do not specify a hydration state (e.g., anhydrous, heptahydrate). The construction of this term is important because the specific form used by Defendants and how its concentration is calculated relative to the claim language could determine infringement. Practitioners may focus on this term because different salt forms have different molecular weights, which can affect concentration calculations and potentially create a non-infringement argument.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language itself uses the general term "dibasic sodium phosphate" without any limitation as to its hydration state, which may support an interpretation covering all forms ('820 Patent, col. 9:44).
    • Evidence for a Narrower Interpretation: The specification discloses an example formulation containing "dibasic sodium phosphate heptahydrate" '820 Patent, Table 1 A defendant may argue this disclosure limits the scope of the broader term in the claims to this specific embodiment.

'623 Patent, Claim 1

  • The Term: "treating obesity"
  • Context and Importance: This phrase defines the purpose of the claimed method. The infringement analysis for inducement will depend on whether the actions encouraged by the Defendants' proposed label fall within the scope of "treating obesity" as understood at the time of the invention.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent specification describes tirzepatide as "useful in the treatment of obesity" without providing a specific, limiting definition '623 Patent, col. 1:35-36 This suggests the term should be given its plain and ordinary meaning in the medical field, which could be broad.
    • Evidence for a Narrower Interpretation: The complaint itself describes the FDA-approved indication for Zepbound® with specific BMI criteria (e.g., BMI ≥ 30 kg/m² or ≥ 27 kg/m² with a comorbid condition) Compl. ¶25 A defendant may argue that "treating obesity" in the patent context should be limited to patients meeting such formal diagnostic criteria, potentially creating a non-infringement argument if their label is worded differently.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement for the method-of-use patents. Induced infringement allegations are based on the assertion that Defendants' proposed product labeling will instruct and encourage physicians and patients to administer the generic products in accordance with the patented methods Compl. ¶86 Compl. ¶105 Contributory infringement is alleged on the basis that the proposed products are especially made for the patented uses and are not suitable for substantial noninfringing use Compl. ¶89 Compl. ¶108
  • Willful Infringement: The complaint alleges that Defendants had knowledge of the asserted patents prior to the litigation. This knowledge is predicated on the patents being listed in the FDA's Orange Book for Mounjaro® and Zepbound® and on Defendants' inclusion of the patents in their Paragraph IV certification notice letters Compl. ¶68 Compl. ¶85 The complaint asserts that Defendants' continued intent to commercialize their products despite this knowledge supports a claim for willful infringement.

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

  1. The Labeling Question: A central issue for the multiple method-of-use patents will be one of induced infringement: does the language in Defendants' proposed product labels for their generic tirzepatide products actively instruct or encourage physicians and patients to follow the specific dosing regimens and treatment methods claimed by Lilly, or have Defendants successfully "carved out" these patented uses to avoid liability?
  2. The Composition Question: A key evidentiary question for the composition-of-matter patents will be one of chemical identity: will discovery confirm that the formulations described in Defendants' ANDA submissions fall within the specific concentration ranges for tirzepatide and key excipients like NaCl and dibasic sodium phosphate, as recited in the claims of patents such as the '820 and '756 Patents?
  3. The Validity Question: A foundational issue, foreshadowed by the Defendants' Paragraph IV certifications, will be the validity of Lilly's patents. The court will likely need to adjudicate Defendants' assertions of invalidity, which may raise questions of obviousness based on prior art related to peptide formulations and diabetes treatment regimens.
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