DCT

1:25-cv-00380

Sumitomo Pharma Switzerland GmbH v. Annora Pharma Pvt Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-00380, D. Del., 08/25/2025
  • Venue Allegations: Plaintiffs allege venue is proper because two defendants, Annora and Hetero Labs Limited, are foreign corporations that may be sued in any judicial district. Venue is also alleged to be proper as to Hetero USA, Inc. because it is a Delaware corporation.
  • Core Dispute: Plaintiffs allege that Defendants' submission of an Abbreviated New Drug Application (ANDA) to the FDA for a generic version of the drug Myfembree® constitutes an act of infringement of five U.S. patents covering the drug's chemical composition and its methods of use for treating uterine fibroids and endometriosis.
  • Technical Context: The technology relates to a pharmaceutical combination therapy using relugolix (a GnRH antagonist) with estradiol and norethindrone acetate to treat hormone-sensitive gynecological conditions while mitigating side effects associated with estrogen suppression.
  • Key Procedural History: This case was initiated under the Hatch-Waxman Act following Defendants' submission of ANDA No. 220123. Plaintiffs allege that Defendants provided Paragraph IV Notice Letters on February 14, 2025, and August 15, 2025, certifying that the patents-in-suit are invalid or will not be infringed by the proposed generic product. The asserted patents are listed in the FDA's "Orange Book" for the approved drug Myfembree®.

Case Timeline

Date Event
2012-09-28 Priority Date for '178 and '714 Patents
2016-09-30 Priority Date for '551, '684, and '812 Patents
2021-05-26 Myfembree® (NDA No. 214846) FDA Approval
2021-06-15 '551 Patent Issued
2023-10-24 '178 Patent Issued
2023-10-24 '812 Patent Issued
2024-04-16 '684 Patent Issued
2025-02-14 Annora's First Paragraph IV Notice Letter
2025-06-10 '714 Patent Issued
2025-06-11 '714 Patent listed in Orange Book
2025-07-16 Plaintiffs provide '714 Patent to Defendants
2025-08-15 Annora's Second Paragraph IV Notice Letter
2025-08-25 Complaint Filing Date

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

U.S. Patent No. 11,795,178 - "Compositions of Thienopyrimidine Derivatives"

  • Patent Identification: U.S. Patent No. 11,795,178 ("the '178 Patent"), "Compositions of Thienopyrimidine Derivatives", issued October 24, 2023 Compl. ¶33

The Invention Explained

  • Problem Addressed: The patent describes a demand for a "safe production method of a thienopyrimidine derivative or a salt thereof which has gonadotropin releasing hormone (GnRH) antagonistic action with high quality (e.g., high purity) in high yield" '178 Patent, col. 2:10-14
  • The Patented Solution: The invention provides a method for producing the thienopyrimidine derivative relugolix with high yield and purity, and claims the resulting solid mixture '178 Patent, abstract The process involves specific chemical synthesis steps and, critically, a recrystallization step to produce a highly pure crystal form, which results in a solid mixture containing a specific impurity at a very low, defined level '178 Patent, col. 2:59-col. 3:4
  • Technical Importance: For a commercially produced active pharmaceutical ingredient (API), controlling impurities is critical for drug safety, efficacy, and regulatory approval. This patent claims a composition defined by a low level of a specific process-related impurity, reflecting a well-controlled and reproducible manufacturing process.

Key Claims at a Glance

  • The complaint asserts at least claims 1 and 25-28 Compl. ¶51
  • Independent Claim 1 is broken down as follows:
    • A mixture comprising 1-(4-[1-(2,6-difluorobenzyl)-5-(dimethylaminomethyl)-3-(6-methoxypyridazin-3-yl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl)-3-methoxyurea;
    • and 6-(4-aminophenyl)-1-(2,6-difluorobenzyl)-5-(dimethylaminomethyl)-3-(6-methoxypyridazin-3-yl)thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione;
    • wherein the mixture is in solid form; and
    • wherein the 6-(4-aminophenyl)-1-(2,6-difluorobenzyl)-5-(dimethylaminomethyl)-3-(6-methoxypyridazin-3-yl)thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione is present in an amount of from about 0.01% to about 0.2% of the mixture, as determined by HPLC.
  • The complaint reserves the right to assert dependent claims Compl. ¶51

U.S. Patent No. 12,325,714 - "Compositions of Thienopyrimidine Derivatives"

  • Patent Identification: U.S. Patent No. 12,325,714 ("the '714 Patent"), "Compositions of Thienopyrimidine Derivatives", issued June 10, 2025 Compl. ¶34

The Invention Explained

  • Problem Addressed: Similar to the '178 patent, the '714 Patent addresses the need for a high-yield, high-purity, and safe production method for the thienopyrimidine derivative relugolix '714 Patent, col. 2:19-24
  • The Patented Solution: This patent claims a solid mixture of relugolix that is defined by the presence of a different, specific impurity-N-[4-[1-(2,6-difluorobenzyl)-5-dimethylaminomethyl-2,4-dioxo-3-(6-oxo-1,6-dihydropyridazin-3-yl)-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl]-N,N-dimethylcarboximidamide-at a concentration of about 0.001% to 0.02% '714 Patent, claim 1 The invention is directed at the resulting composition from a controlled manufacturing process.
  • Technical Importance: Claiming a composition by its specific impurity profile is a strategy to protect a proprietary manufacturing process. The presence of a particular impurity, even at trace levels, can serve as a "fingerprint" of the patented synthesis route.

Key Claims at a Glance

  • The complaint asserts at least claims 1, 11, and 19 Compl. ¶61
  • Independent Claim 1 is broken down as follows:
    • A solid mixture comprising 1-{4-[1-(2,6-difluorobenzyl)-5-dimethylaminomethyl-3-(6-methoxypyridazin-3-yl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl}-3-methoxyurea or a salt thereof;
    • and N-[4-[1-(2,6-difluorobenzyl)-5-dimethylaminomethyl-2,4-dioxo-3-(6-oxo-1,6-dihydropyridazin-3-yl)-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl]-N,N-dimethylcarboximidamide;
    • wherein the N-[4-[1-(2,6-difluorobenzyl)-5-dimethylaminomethyl-2,4-dioxo-3-(6-oxo-1,6-dihydropyridazin-3-yl)-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl]-N,N-dimethylcarboximidamide is present in an amount of about 0.001% to about 0.02% of the mixture, as determined by HPLC.
  • The complaint reserves the right to assert dependent claims Compl. ¶61

U.S. Patent No. 11,033,551 - "Methods of Treating Uterine Fibroids"

  • Patent Identification: U.S. Patent No. 11,033,551 ("the '551 Patent"), "Methods of Treating Uterine Fibroids", issued June 15, 2021 Compl. ¶35
  • Technology Synopsis: The patent discloses methods for treating estrogen-sensitive conditions, particularly uterine fibroids, by administering a specific combination therapy '551 Patent, col. 2:18-26 The therapy combines a GnRH antagonist (relugolix) with a hormone replacement regimen (estradiol and a progestin) to treat the underlying condition while managing side effects like bone mineral density loss that can arise from suppressing estrogen alone '551 Patent, col. 3:20-35 '551 Patent, col. 3:36-51
  • Asserted Claims: Claims 1, 5-6, 9, 10-15, 19-21, and 25 are asserted Compl. ¶72 Independent claims include 1, 10, and 20.
  • Accused Features: The complaint alleges that Defendants' proposed generic product, which contains the same combination of active ingredients (relugolix, estradiol, and norethindrone acetate), will be used according to its label to treat uterine fibroids, thereby infringing the patented method Compl. ¶¶72-75

U.S. Patent No. 11,957,684 - "Treatment of Heavy Menstrual Bleeding Associated with Uterine Fibroids"

  • Patent Identification: U.S. Patent No. 11,957,684 ("the '684 Patent"), "Treatment of Heavy Menstrual Bleeding Associated with Uterine Fibroids", issued April 16, 2024 Compl. ¶36
  • Technology Synopsis: The '684 Patent is directed to methods of treating heavy menstrual bleeding associated with uterine fibroids in pre-menopausal women '684 Patent, abstract The claimed method involves daily oral administration of a single dosage form containing about 40 mg of relugolix, about 1.0 mg of estradiol, and about 0.5 mg norethindrone acetate '684 Patent, claim 1
  • Asserted Claims: Claims 1-5, 7, 11, 16, and 20-22 are asserted Compl. ¶82 Independent claims include 1, 10, and 20.
  • Accused Features: The Defendants' ANDA product is a single tablet containing the exact dosages recited in the patent's independent claims and is intended for treating heavy menstrual bleeding associated with uterine fibroids, which Plaintiffs allege will lead to infringement Compl. ¶¶1, 31, 82-85

U.S. Patent No. 11,793,812 - "Methods of Treating Endometriosis"

  • Patent Identification: U.S. Patent No. 11,793,812 ("the '812 Patent"), "Methods of Treating Endometriosis", issued October 24, 2023 Compl. ¶37
  • Technology Synopsis: The patent claims methods for treating pain associated with endometriosis by orally administering the same three-drug combination: relugolix, estradiol, and norethindrone acetate '812 Patent, abstract The goal is to provide pain relief while using hormone add-back therapy to maintain bone mineral density within a specified percentage of the patient's baseline '812 Patent, claim 1
  • Asserted Claims: Claims 1 and 4 are asserted Compl. ¶92 Claim 1 is independent.
  • Accused Features: Plaintiffs allege that the Defendants' ANDA product will be prescribed and used for the treatment of pain associated with endometriosis, one of the approved indications for Myfembree®, thereby infringing the patented method Compl. ¶¶31, 92-95

III. The Accused Instrumentality

Product Identification

  • Defendants' Abbreviated New Drug Application (ANDA) No. 220123 for tablets containing 40 mg of relugolix, 1 mg of estradiol, and 0.5 mg of norethindrone acetate (the "ANDA Product") Compl. ¶1

Functionality and Market Context

  • The ANDA Product is a proposed generic equivalent of Plaintiffs' FDA-approved drug, Myfembree® Compl. ¶1 The complaint alleges that the ANDA Product contains the same active ingredients, dosage form, and strength, and is bioequivalent to Myfembree® Compl. ¶41 The filing of the ANDA seeks FDA approval to manufacture and sell this generic version for the same indications as Myfembree®, namely the management of heavy menstrual bleeding associated with uterine fibroids and pain associated with endometriosis Compl. ¶¶1, 31 The act of infringement alleged in an ANDA case is the submission of the application itself under 35 U.S.C. § 271(e)(2)(A) Compl. ¶1 No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

'178 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A mixture comprising 1-(4-[1-(2,6-difluorobenzyl)-5-(dimethylaminomethyl)-3-(6-methoxypyridazin-3-yl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl)-3-methoxyurea; The ANDA Product contains 40 mg of relugolix, which is the specified chemical compound. ¶1; ¶41 col. 3:63-col. 4:1
and 6-(4-aminophenyl)-1-(2,6-difluorobenzyl)-5-(dimethylaminomethyl)-3-(6-methoxypyridazin-3-yl)thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione; The complaint alleges that the ANDA Product will infringe, which requires that it contains this specified impurity. ¶51; ¶52 col. 4:2-10
wherein the mixture is in solid form; The ANDA Product is a solid tablet. ¶1 col. 4:11
and wherein the [impurity] is present in an amount of from about 0.01% to about 0.2% of the mixture, as determined by HPLC. The complaint alleges infringement, thereby asserting that the impurity is present in the ANDA product within this concentration range. ¶51; ¶52 col. 4:14-18

'714 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A solid mixture comprising 1-{4-[1-(2,6-difluorobenzyl)-5-dimethylaminomethyl-3-(6-methoxypyridazin-3-yl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl}-3-methoxyurea or a salt thereof; The ANDA Product is a solid tablet containing relugolix. ¶1; ¶41 col. 2:56-65
and N-[4-[1-(2,6-difluorobenzyl)-5-dimethylaminomethyl-2,4-dioxo-3-(6-oxo-1,6-dihydropyridazin-3-yl)-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl]-N,N-dimethylcarboximidamide; The complaint alleges that the ANDA Product will infringe, which requires that it contains this specified impurity. ¶61; ¶62 col. 3:1-12
wherein the [impurity] is present in an amount of about 0.001% to about 0.02% of the mixture, as determined by HPLC. The complaint alleges infringement, thereby asserting that the impurity is present in the ANDA product within this concentration range. ¶61; ¶62 col. 3:13-17

Identified Points of Contention

  • Evidentiary Questions: The central dispute for the '178 and '714 patents will be factual and evidentiary. Do the API specifications and stability data within the confidential ANDA filing show the presence of the specific impurities recited in the claims? If so, are those impurities present within the claimed concentration ranges? The complaint alleges this is the case, but proof will depend on discovery of the ANDA's contents.
  • Induced Infringement Questions: For the method patents ('551, '684, and '812), the analysis will focus on induced infringement under § 271(b). The primary question is whether the proposed label for the ANDA product instructs or encourages physicians and patients to administer the drug in a way that practices the claimed methods for treating uterine fibroids and endometriosis. Since the ANDA product seeks the same indications as the brand-name drug, this is a central point of the litigation.

V. Key Claim Terms for Construction

  • The Term: "about"
  • Context and Importance: This term appears in the dosage and concentration limitations of all asserted patents (e.g., "about 40 mg," "about 0.01% to about 0.2%"). In ANDA litigation, where the generic product's composition is precisely defined, the scope of "about" can be determinative. If the defendant's product specifications fall just outside the numerical limits, the interpretation of "about" will decide infringement. Practitioners may focus on this term because even slight variations in product composition could be used to argue non-infringement, making the breadth of this term critical.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specifications of the patents-in-suit frequently use "about" when describing a wide range of potential dosages and formulations, suggesting the patentees intended the term to convey numerical flexibility beyond exact values (e.g., '551 Patent, col. 4:1-3, describing relugolix from "about 10 mg to about 60 mg").
    • Evidence for a Narrower Interpretation: The patents also disclose highly specific embodiments and clinical trial data centered on the precise 40 mg / 1.0 mg / 0.5 mg combination (e.g.,'684 Patent, claim 1). A defendant may argue that these specific examples and the precise nature of pharmaceutical chemistry limit the scope of "about" to little more than the standard range of acceptable manufacturing or measurement variability. The Certificate of Correction for the '551 patent, which explicitly corrected a claim to read "about 1.0 mg of estradiol," could be argued to emphasize the criticality of the specific number, potentially narrowing the interpretation of "about."

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement for all five patents-in-suit. The inducement allegation is based on the assertion that Defendants' proposed product labeling will actively encourage and instruct healthcare providers and patients to use the ANDA product in a manner that infringes the patented methods of use Compl. ¶75 Compl. ¶85 Compl. ¶95 The contributory infringement allegation is based on the assertion that the ANDA product is a material component of the invention, is especially adapted for infringing use, and is not a staple article with substantial non-infringing uses Compl. ¶76 Compl. ¶86 Compl. ¶96
  • Willful Infringement: The complaint does not explicitly use the term "willful infringement," but for each count it requests a judgment that this is an "exceptional case" under 35 U.S.C. § 285, which can entitle the prevailing party to attorneys' fees Compl. ¶58 Compl. ¶69 Compl. ¶79 Compl. ¶89 Compl. ¶99 The factual basis alleged is that Defendants had pre-suit knowledge of the patents through their listing in the FDA's Orange Book and through Paragraph IV notice letters, but proceeded with the ANDA filing nonetheless Compl. ¶42 Compl. ¶45 Compl. ¶47

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

  • A primary issue for the composition-based '178 and '714 patents will be one of evidentiary proof: does the Defendants' generic relugolix, as described in their confidential ANDA, contain the exact impurities within the specific, narrow concentration ranges claimed by the patents? The outcome will likely depend on a technical, fact-intensive analysis of the Defendants' manufacturing process and final product specifications.
  • For the method-of-use patents ('551, '684, '812), the case will likely turn on the question of induced infringement: will the instructions and indications for use on the Defendants' proposed drug label be found to actively encourage medical professionals and patients to perform the steps of the patented treatment methods? Because the generic seeks the same indications as the branded drug, this analysis will focus on the specific language of the proposed label compared to the claim language.
  • A potentially dispositive underlying question for all patents is one of claim construction: how will the court define the scope of the term "about" as it applies to the claimed dosages and impurity levels? The answer could either confirm a literal infringement or provide Defendants a path to argue their product falls outside the claims' boundaries.