DCT
1:25-cv-01383
Astellas Pharma Inc v. Renata Ltd
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Astellas Pharma Inc. (Japan), Astellas Ireland Co., Ltd. (Ireland), and Astellas Pharma Global Development, Inc. (Delaware)
- Defendant: Renata Limited (Bangladesh) and Somerset Therapeutics, LLC (Delaware)
- Plaintiff’s Counsel: Kirkland & Ellis LLP; McCarter & English, LLP
- Case Identification: 1:25-cv-01383, D. Del., 11/14/2025
- Venue Allegations: Venue is alleged to be proper in the District of Delaware based on Defendant Somerset Therapeutics, LLC’s incorporation in Delaware and Defendant Renata Limited’s status as a foreign corporation with sufficient U.S. contacts, making venue proper under 28 U.S.C. § 1391(c)(3) and Fed. R. Civ. P. 4(k)(2).
- Core Dispute: Plaintiff alleges that Defendants’ filing of an Abbreviated New Drug Application (ANDA) to market a generic version of Plaintiff’s Myrbetriq® (mirabegron) extended-release tablets constitutes an act of infringement of four U.S. patents related to pharmaceutical formulations and methods of use.
- Technical Context: The dispute centers on modified-release oral drug formulations designed to provide consistent therapeutic effects for the treatment of overactive bladder by mitigating pharmacokinetic variability associated with food intake.
- Key Procedural History: This action was triggered by Defendants’ submission of a Paragraph IV certification to the FDA, asserting that the patents-in-suit are invalid, unenforceable, or will not be infringed by their proposed generic product. The complaint notes that a Request for a Certificate of Correction was filed for U.S. Patent No. 12,059,409 to correct a typographical error in a claim.
Case Timeline
| Date | Event |
|---|---|
| 2008-09-30 | Earliest Priority Date for all Patents-in-Suit |
| 2012-06-28 | FDA Approval of Myrbetriq® (NDA No. 202611) |
| 2013-06-20 | FDA Issues Bioequivalence Guidance for Mirabegron ANDAs |
| 2020-11-24 | U.S. Patent No. 10,842,780 Issues |
| 2023-07-25 | U.S. Patent No. 11,707,451 Issues |
| 2024-08-13 | U.S. Patent No. 12,059,409 Issues |
| 2024-08-26 | Request for Certificate of Correction filed for the ’409 Patent |
| 2024-09-24 | U.S. Patent No. 12,097,189 Issues |
| 2025-09-30 | Defendant Renata submits ANDA No. 220792 to the FDA |
| 2025-09-30 | Defendant Renata sends Paragraph IV Notice Letter to Plaintiff |
| 2025-11-14 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 10,842,780 - "Pharmaceutical Composition for Modified Release"
Issued November 24, 2020
The Invention Explained
- Problem Addressed: The patent describes how conventional formulations of the active ingredient mirabegron exhibit a significant "food effect," where pharmacokinetic data such as maximum plasma concentration (Cmax) and total drug exposure (AUC) vary unexpectedly depending on whether the drug is taken with food. (’780 Patent, col. 6:49-62).
- The Patented Solution: The invention is a modified-release pharmaceutical composition that controls the drug's release rate to reduce the food effect. It achieves this by combining the active ingredient with a "hydrogel-forming polymer" and a highly water-soluble "additive" that ensures water penetrates into the tablet, thereby creating a hydrogel that releases the drug at a controlled rate regardless of food intake. (’780 Patent, Abstract; col. 6:55-68).
- Technical Importance: This formulation aims to provide more predictable drug absorption and consistent therapeutic efficacy for patients, irrespective of meals, which can enhance safety and patient compliance. (’780 Patent, col. 6:8-10).
Key Claims at a Glance
- The complaint asserts infringement of "one or more claims" without specifying them (Compl. ¶80). Independent claim 1 is representative of the core composition claims.
- Independent Claim 1 recites:
- A pharmaceutical composition comprising 10 mg to 200 mg of mirabegron or a salt thereof;
- In a sustained release hydrogel-forming formulation comprising a hydrogel-forming polymer with an average molecular weight of 100,000 to 8,000,000;
- And an additive with a water solubility of at least 0.1 g/mL at 20±5° C;
- Wherein the drug dissolution rate is 39% or less after 1.5 hours and at least 75% after 7 hours, under specified USP testing conditions.
U.S. Patent No. 12,059,409 - "Pharmaceutical Composition for Modified Release"
Issued August 13, 2024
The Invention Explained
- Problem Addressed: The technology addresses the same food effect problem described in the ’780 Patent, where the bioavailability of mirabegron changes significantly when administered with food. (’409 Patent, col. 6:50-62).
- The Patented Solution: The patent claims a tablet formulation of mirabegron that uses a sustained release hydrogel-forming system. This system includes a hydrogel-forming polymer within a specific molecular weight range and a water-soluble additive, designed to control drug release and mitigate pharmacokinetic variability caused by food. (’409 Patent, col. 7:5-16).
- Technical Importance: The formulation seeks to ensure more consistent plasma concentrations of mirabegron, which is important for maintaining a stable therapeutic effect in the treatment of overactive bladder. (’409 Patent, col. 6:8-10).
Key Claims at a Glance
- The complaint identifies Independent Claim 1 as being asserted (Compl. ¶25).
- Independent Claim 1 recites:
- A tablet comprising 10 mg to 200 mg of mirabegron or a salt thereof;
- In a sustained release hydrogel-forming formulation comprising a hydrogel-forming polymer with an average molecular weight of 200,000 to 7,000,000;
- And an additive with a water solubility of at least 0.1 g/mL at 20+5° C (a typographical error which is the subject of a pending Certificate of Correction request to change it to 20±5° C).
U.S. Patent No. 11,707,451 - "Pharmaceutical Composition for Modified Release"
Issued July 25, 2023
- Technology Synopsis: The ’451 Patent claims a method of treating overactive bladder with a "reduced food effect." This method comprises orally administering a tablet containing mirabegron in a sustained release formulation that provides a continuous drug release for at least 4 hours, where the reduced food effect is determined by comparison to an immediate-release formulation. (Compl. ¶31).
- Asserted Claims: The complaint does not specify which independent claims are asserted.
- Accused Features: The complaint alleges that Defendants' proposed generic product, by being bioequivalent to Myrbetriq®, will necessarily provide continuous drug release for at least four hours and exhibit a reduced food effect, and that its label will instruct use for treating overactive bladder. (Compl. ¶¶103-105).
U.S. Patent No. 12,097,189 - "Pharmaceutical Composition for Modified Release"
Issued September 24, 2024
- Technology Synopsis: The ’189 Patent claims methods of treating overactive bladder with a reduced food effect, wherein the food effect is specifically defined as a difference in the rate of decrease of Cmax of 10% or more compared to an immediate-release mirabegron capsule. The claimed method involves administering a tablet with mirabegron in a sustained release hydrogel-forming formulation. (Compl. ¶37).
- Asserted Claims: The complaint does not specify which independent claims are asserted.
- Accused Features: The complaint alleges that Defendants' proposed generic product, in order to be bioequivalent, will meet the claimed Cmax reduction criteria, and that its proposed label will instruct users to perform the infringing method of treatment. (Compl. ¶¶114-116).
III. The Accused Instrumentality
Product Identification
- Defendants’ 25 mg and 50 mg mirabegron extended-release oral tablets, for which Abbreviated New Drug Application (ANDA) No. 220792 was submitted to the FDA (the "ANDA Products") (Compl. ¶7).
Functionality and Market Context
- The complaint alleges that for the ANDA Products to be approved as a generic version of Myrbetriq®, they must be bioequivalent to it (Compl. ¶62, ¶67). This regulatory requirement, according to the complaint, necessitates that the ANDA Products have the same active ingredient, dosage form, and administration method as Myrbetriq® (Compl. ¶70). Crucially, the complaint alleges that to achieve bioequivalence, the ANDA Products must use a sustained release hydrogel-forming formulation and match Myrbetriq's dissolution profile, thereby copying the patented technology (Compl. ¶82, ¶83). The complaint includes a table from the FDA's website showing the dissolution requirements for mirabegron ANDA filers, which specifies testing in a phosphate buffer at pH 6.8 using a USP Apparatus I (Compl. ¶65, p. 12).
IV. Analysis of Infringement Allegations
U.S. Patent No. 10,842,780 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a pharmaceutical composition, comprising 10 mg to 200 mg of (R)-2-(2-aminothiazol-4-yl)-4'-[2-[(2-hydroxy-2-phenylethyl)amino]ethyl]acetic acid anilide, or a pharmaceutically acceptable salt thereof | Defendants’ ANDA Products are extended-release tablets containing 25 mg or 50 mg of the active ingredient mirabegron. | ¶81 | col. 8:46-49 |
| in a sustained release hydrogel-forming formulation comprising a hydrogel-forming polymer having an average molecular weight of 100,000 to 8,000,000 | To establish bioequivalence, Defendants' ANDA Products allegedly use a sustained release hydrogel-forming formulation equivalent to that in Myrbetriq® Tablets, which employs a polymer (polyethylene oxide) with a molecular weight within this range. | ¶52, ¶83 | col. 7:20-23 |
| and an additive having a water solubility of at least 0.1 g/mL at 20±5° C. | Defendants' ANDA Products allegedly contain an additive (such as polyethylene glycol, copied from Myrbetriq®) that meets the claimed water solubility requirement. | ¶53, ¶83 | col. 7:8-15 |
| wherein a drug dissolution rate from the pharmaceutical composition is 39% or less after 1.5 hours, and at least 75% after 7 hours, as measured in accordance with United States Pharmacopoeia... | To achieve bioequivalence with the reference drug Myrbetriq®, Defendants' ANDA Products allegedly will have equivalent dissolution properties that meet this claimed profile. | ¶55, ¶83 | col. 20:43-49 |
U.S. Patent No. 12,059,409 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A tablet comprising 10 mg to 200 mg of [mirabegron], or a pharmaceutically acceptable salt thereof | Defendants’ ANDA Products are tablets containing 25 mg or 50 mg of mirabegron. | ¶92 | col. 8:46-49 |
| in a sustained release hydrogel-forming formulation comprising a hydrogel-forming polymer having an average molecular weight of 200,000 to 7,000,000 | By copying the Myrbetriq® formulation to achieve bioequivalence, Defendants’ ANDA Products allegedly use a hydrogel-forming polymer with a molecular weight within the claimed range. | ¶52, ¶94 | col. 7:20-23 |
| and an additive having a water solubility of at least 0.1 g/mL at 20+5° [sic] C | The ANDA Products allegedly contain an additive that meets the claimed water solubility requirement, as required to be bioequivalent to Myrbetriq®. | ¶53, ¶94 | col. 7:8-15 |
- Identified Points of Contention:
- Evidentiary Questions: The complaint's infringement theory is premised on the regulatory requirement of bioequivalence, leading to the allegation that Defendants must have copied the patented formulation (Compl. ¶82, ¶93). A primary point of contention will be a factual one: does Defendants' actual ANDA formulation, once revealed through discovery, contain a hydrogel-forming polymer and an additive with the specific molecular weights and solubilities required by the claims?
- Scope Questions: A potential issue is whether a generic formulation could be designed to be bioequivalent for FDA purposes while technically falling outside the literal scope of the claims. For example, a dispute may arise over whether Defendants’ chosen polymer has an "average molecular weight" that is definitively within the claimed range, or whether their additive meets the precise "water solubility" threshold under the appropriate test conditions.
V. Key Claim Terms for Construction
The Term: "sustained release hydrogel-forming formulation"
- Context and Importance: This term defines the core drug delivery system of the invention. Its construction will be critical in determining whether Defendants’ formulation, which is alleged to be such a system to achieve bioequivalence, falls within the scope of the claims.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specifications of the asserted patents provide numerous examples of different hydrogel-forming polymers (e.g., polyethylene oxide, HPMC, HPC) and additives (e.g., PEG, PVP, D-mannitol), suggesting the term is not limited to one specific combination but rather encompasses a functional class of formulations. (’780 Patent, col. 7:50-54; col. 10:17-44).
- Evidence for a Narrower Interpretation: The claims themselves tie the "formulation" to specific functional outcomes, such as the dissolution profile in the ’780 Patent. A party might argue that a formulation that does not meet these functional limitations cannot be considered a "sustained release hydrogel-forming formulation" as claimed. (’780 Patent, col. 20:43-49).
The Term: "average molecular weight"
- Context and Importance: This term provides a quantitative boundary for a key component of the invention, the hydrogel-forming polymer. The method used to calculate this average and the precision of the measurement will be central to the infringement analysis. Practitioners may focus on this term because different measurement techniques (e.g., weight-average vs. number-average) can yield different results, potentially moving an accused polymer into or out of the claimed range.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patents list commercial product names (e.g., "Polyox WSR-N-60K") and their corresponding "average molecular weight," which could suggest that the term should be understood according to the conventions used by suppliers in the field. (’780 Patent, col. 9:60-62).
- Evidence for a Narrower Interpretation: The patents do not specify a particular method for calculating the average molecular weight. A party could argue that in the absence of a specific definition, a particular scientific standard or method should apply, potentially narrowing the range of polymers that meet the limitation.
VI. Other Allegations
- Indirect Infringement: The complaint alleges induced infringement on the basis that Defendants’ proposed product label will instruct healthcare professionals and patients to administer the generic tablets for the treatment of overactive bladder, thereby directly infringing the asserted method claims (Compl. ¶85, ¶105, ¶116). Contributory infringement is also alleged, based on the assertion that the generic tablets are a material part of the claimed invention and are not a staple article of commerce suitable for substantial non-infringing use (Compl. ¶86, ¶106, ¶117).
- Willful Infringement: While the complaint does not contain a separate count for willful infringement, it alleges facts that may support such a claim. It asserts that Defendants had pre-suit knowledge of the patents via their Paragraph IV certification letter (Compl. ¶8) and will have actual knowledge of the patents at least by the filing date of the complaint (Compl. ¶87, ¶96, ¶107, ¶118).
VII. Analyst’s Conclusion: Key Questions for the Case
- A central evidentiary question will be one of technical identity: will discovery confirm the complaint's allegation, based on bioequivalence requirements, that Defendants' ANDA product contains a hydrogel-forming polymer and a soluble additive with the specific "average molecular weight" and "water solubility" properties recited in the asserted claims?
- A key legal question will be one of claim scope: can the term "sustained release hydrogel-forming formulation", which is defined in part by functional dissolution characteristics, be construed to cover a formulation that is bioequivalent for regulatory purposes but may differ in its specific components or mechanism of release from the embodiments described in the patents?
- A third major issue, raised by Defendants’ Paragraph IV letter but not detailed in the complaint, will be validity: can Defendants establish by clear and convincing evidence that the claimed formulation, designed to solve the known problem of "food effect," was obvious to a person of ordinary skill in the art at the time of the invention?