DCT

1:25-cv-00045

Astellas Pharma Inc v. Creekwood Pharma LLC

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-00045, D. Del., 01/10/2025
  • Venue Allegations: Venue is alleged as proper in the District of Delaware based on Defendant's incorporation in that state.
  • Core Dispute: Plaintiff alleges that Defendant’s filing of an Abbreviated New Drug Application (ANDA) for generic mirabegron extended-release tablets constitutes an act of infringement of four patents related to pharmaceutical compositions and methods of treatment.
  • Technical Context: The technology concerns extended-release formulations of mirabegron, the active ingredient in the drug Myrbetriq®, which is used for the treatment of overactive bladder.
  • Key Procedural History: This patent infringement action was initiated under the Hatch-Waxman Act following Defendant’s November 22, 2024 notice letter, which communicated the submission of ANDA No. 219599 with a Paragraph IV certification. This certification asserts that the patents-in-suit are invalid, unenforceable, and/or will not be infringed by the proposed generic product. The complaint notes that U.S. Patent Nos. 10,842,780 and 11,707,451 are subject to FDA pediatric exclusivity through March 28, 2030. A Request for a Certificate of Correction for U.S. Patent No. 12,059,409 was filed on August 26, 2024.

Case Timeline

Date Event
2008-09-30 Earliest Priority Date for ’780 and ’409 Patents
2010-03-29 Earliest Priority Date for ’451 and ’189 Patents
2012-06-28 FDA approves NDA for Myrbetriq® Tablets
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 ’409 Patent
2024-09-24 U.S. Patent No. 12,097,189 Issues
2024-11-22 Creekwood sends Paragraph IV Notice Letter to Astellas
2025-01-10 Complaint for Patent Infringement filed

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

U.S. Patent No. 10,842,780 - "Pharmaceutical Composition for Modified Release"

  • Patent Identification: U.S. Patent No. 10,842,780, titled “Pharmaceutical Composition for Modified Release,” issued November 24, 2020 (Compl. ¶14).

The Invention Explained

  • Problem Addressed: The patent’s background section states that conventional formulations of the active ingredient, mirabegron, exhibited undesirable pharmacokinetic variability depending on food intake, noting that both the maximum drug concentration (Cmax) and total drug exposure (AUC) decreased significantly when the drug was taken with food versus in a fasted state (’780 Patent, col. 1:50-58).
  • The Patented Solution: The invention is a modified-release composition designed to reduce this "food effect" by controlling the drug's release rate. It achieves this by combining the active ingredient with two key excipients: a "hydrogel-forming polymer" and an "additive which ensures penetration of water into the pharmaceutical composition," also referred to as a hydrophilic base (’780 Patent, col. 1:21-30). This combination creates a formulation that swells into a gel, slowing and sustaining the release of mirabegron and making its absorption less dependent on the presence of food in the gastrointestinal tract (’780 Patent, col. 2:56-61).
  • Technical Importance: This approach aims to provide more consistent and predictable drug absorption, which is critical for maintaining stable therapeutic efficacy and safety for patients regardless of when they take the medication in relation to meals (Compl. ¶¶48-49).

Key Claims at a Glance

  • The complaint asserts infringement of "one or more claims" without specifying particular claims (Compl. ¶72). Independent claim 1 is analyzed here as a representative claim.
  • Claim 1 of the ’780 Patent recites the following primary elements:
    • A pharmaceutical composition comprising 10 mg to 200 mg of mirabegron.
    • The composition is in a sustained release hydrogel-forming formulation.
    • The formulation comprises a hydrogel-forming polymer with an average molecular weight of 100,000 to 8,000,000, where the polymer is selected from a specific group including polyethylene oxide and HPMC.
    • The formulation also comprises an additive with a water solubility of at least 0.1 g/mL at 20±5° C., where the additive is selected from a specific group of hydrophilic compounds.
    • The composition has a specific in vitro drug dissolution rate: 39% or less after 1.5 hours and at least 75% after 7 hours, under specified USP test conditions.
  • The complaint reserves the right to assert additional claims.

U.S. Patent No. 12,059,409 - "Pharmaceutical Composition for Modified Release"

  • Patent Identification: U.S. Patent No. 12,059,409, titled “Pharmaceutical Composition for Modified Release,” issued August 13, 2024 (Compl. ¶19).

The Invention Explained

  • Problem Addressed: The ’409 Patent, which shares a specification with the ’780 Patent, addresses the same technical problem of food-dependent variability in the pharmacokinetics of mirabegron (’409 Patent, col. 1:50-58).
  • The Patented Solution: The solution is substantively identical to that of the ’780 Patent: a modified-release tablet using a hydrogel-forming polymer and a hydrophilic additive to ensure a controlled release of the active ingredient, thereby mitigating the impact of food on drug absorption (’409 Patent, col. 1:21-30).
  • Technical Importance: The invention provides a formulation that enables more consistent therapeutic outcomes for overactive bladder by normalizing drug exposure regardless of a patient's food intake (Compl. ¶¶48-49).

Key Claims at a Glance

  • The complaint asserts infringement of "one or more claims" without specifying particular claims (Compl. ¶82). Independent claim 1 is analyzed here as a representative claim.
  • Claim 1 of the ’409 Patent recites the following primary elements:
    • A tablet comprising 10 mg to 200 mg of mirabegron.
    • The tablet is in a sustained release hydrogel-forming formulation.
    • The formulation comprises a hydrogel-forming polymer with an average molecular weight of 200,000 to 7,000,000.
    • The formulation also comprises an additive with a water solubility of at least 0.1 g/mL at 20±5° C.
    • The tablet has a specific in vitro drug dissolution rate: 39% or less after 1.5 hours and at least 75% after 7 hours, under specified USP test conditions.
  • The complaint reserves the right to assert additional claims.

U.S. Patent No. 11,707,451 - "Pharmaceutical Composition for Modified Release"

  • Patent Identification: U.S. Patent No. 11,707,451, "Pharmaceutical Composition for Modified Release," issued July 25, 2023 (Compl. ¶23).
  • Technology Synopsis: This patent claims a method of treating overactive bladder with a "reduced food effect." The patented method comprises orally administering a mirabegron tablet in a sustained release formulation that provides a continuous drug release for at least 4 hours, wherein the reduced food effect is determined in comparison to an immediate release formulation of mirabegron (Compl. ¶24).
  • Asserted Claims: Independent claim 1 (Compl. ¶¶90-91).
  • Accused Features: Creekwood’s ANDA product, by virtue of being a bioequivalent sustained-release formulation, is alleged to provide a continuous drug release and a reduced food effect; its product label is alleged to instruct for the infringing use of treating overactive bladder (Compl. ¶¶93-94, 96).

U.S. Patent No. 12,097,189 - "Pharmaceutical Composition for Modified Release"

  • Patent Identification: U.S. Patent No. 12,097,189, "Pharmaceutical Composition for Modified Release," issued September 24, 2024 (Compl. ¶29).
  • Technology Synopsis: This patent claims a method for treating overactive bladder with a reduced food effect, further quantifying this effect as "a difference in a rate of decrease of Cmax of 10% or more" when compared to an immediate release capsule. The method involves administering a tablet comprising mirabegron in a sustained release hydrogel-forming formulation that provides continuous drug release for at least 4 hours (Compl. ¶30).
  • Asserted Claims: Independent claim 1 (Compl. ¶¶101-102).
  • Accused Features: Creekwood’s ANDA product is alleged to meet the Cmax reduction and continuous release limitations due to its required bioequivalence to Myrbetriq®, and its label is alleged to instruct the infringing use (Compl. ¶¶104-105, 107).

III. The Accused Instrumentality

Product Identification

  • Creekwood’s proposed generic mirabegron extended-release oral tablets, 25 mg and 50 mg, as described in ANDA No. 219599 (“Creekwood ANDA Products”) (Compl. ¶6).

Functionality and Market Context

  • The complaint alleges that for its ANDA to be approved by the FDA, Creekwood's product must be bioequivalent to the reference listed drug, Myrbetriq® Tablets (Compl. ¶54). This regulatory requirement allegedly necessitates that Creekwood's ANDA Products have the same active ingredient, dosage form, and method of administration as Myrbetriq® (Compl. ¶61). The complaint further alleges that to establish bioequivalence, Creekwood was required by FDA guidance to conduct comparative dissolution studies against Myrbetriq®, ensuring its product exhibits equivalent dissolution properties (Compl. ¶¶57-58). The complaint provides a table from the FDA's website listing the required dissolution testing parameters for mirabegron ANDA filers to establish bioequivalence (Compl. ¶57). Because Myrbetriq® is alleged to use a sustained release hydrogel-forming formulation, the complaint alleges on information and belief that Creekwood "copied from the Myrbetriq® Tablets formulation" and that its product therefore uses the "same as or equivalent" formulation to achieve the required bioequivalence (Compl. ¶¶74-75, 84-85).

IV. Analysis of Infringement Allegations

The core of the infringement allegation is that by seeking FDA approval for a generic drug that is bioequivalent to Myrbetriq®, Creekwood has created a product that will necessarily practice the inventions claimed in the patents-in-suit.

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...mirabegron... Creekwood's ANDA Products are extended-release tablets containing either 25 mg or 50 mg of mirabegron. ¶73 col. 1:17-21
in a sustained release hydrogel-forming formulation... Creekwood's ANDA Products are alleged to use a sustained release hydrogel-forming formulation equivalent to that of Myrbetriq® Tablets to establish bioequivalence. ¶75 col. 1:24-26
comprising a hydrogel-forming polymer having an average molecular weight of 100,000 to 8,000,000... To match Myrbetriq®'s performance, Creekwood's formulation is alleged to contain a polymer with these properties, such as the polyethylene oxide used in Myrbetriq®. ¶¶44, 74 col. 7:19-24
and an additive having a water solubility of at least 0.1 g/mL at 20±5° C. To match Myrbetriq®'s performance, Creekwood's formulation is alleged to contain an additive with these properties, such as the polyethylene glycol used in Myrbetriq®. ¶¶45, 74 col. 7:8-14
wherein a drug dissolution rate...is 39% or less after 1.5 hours, and at least 75% after 7 hours... Creekwood was required by FDA guidance to match Myrbetriq®'s dissolution profile to establish bioequivalence, which allegedly meets this limitation. ¶¶47, 75 col. 19:40-49

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... Creekwood's ANDA Products are extended-release tablets containing either 25 mg or 50 mg of mirabegron. ¶83 col. 1:17-21
in a sustained release hydrogel-forming formulation... Creekwood's ANDA Products are alleged to use a sustained release hydrogel-forming formulation equivalent to that of Myrbetriq® Tablets. ¶85 col. 1:24-26
comprising a hydrogel-forming polymer having an average molecular weight of 200,000 to 7,000,000... To establish bioequivalence, Creekwood's formulation is alleged to contain a polymer with these properties, mirroring the polyethylene oxide used in Myrbetriq®. ¶¶44, 84 col. 7:19-24
and an additive having a water solubility of at least 0.1 g/mL at 20±5° C. To establish bioequivalence, Creekwood's formulation is alleged to contain an additive with these properties, mirroring the polyethylene glycol used in Myrbetriq®. ¶¶45, 84 col. 7:8-14
wherein the tablet has a drug dissolution rate...of 39% or less after 1.5 hours, and at least 75% after 7 hours... It is alleged that Creekwood's ANDA Products will meet this dissolution profile because of the bioequivalence requirements set by the FDA. ¶¶47, 85 col. 19:40-49

Identified Points of Contention

  • Scope Questions: The central dispute may concern whether achieving bioequivalence under FDA guidelines necessarily requires infringement of the patent claims. A key question for the court will be whether it is possible for the accused product to be bioequivalent to Myrbetriq® without literally meeting every limitation of the asserted claims, such as the specific molecular weight ranges of the polymer.
  • Technical Questions: The complaint's infringement allegations are based on information and belief, inferred from regulatory requirements. A primary technical question will be what the evidence obtained during discovery reveals about the actual composition of Creekwood's ANDA Products. For instance, what specific hydrogel-forming polymer and additive does the accused product use, and what are their measured properties (e.g., molecular weight, solubility)?

V. Key Claim Terms for Construction

  • The Term: "average molecular weight"

    • Context and Importance: This term appears in the independent claims of both the ’780 and ’409 patents with specific numerical ranges. The method used to calculate this "average" (e.g., number-average, weight-average) is not specified in the claims and can yield different results for the same polymer. Practitioners may focus on this term because the infringement determination could depend entirely on the methodology chosen to measure this property for the polymer in Creekwood's product.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The claims recite the term without specifying a particular measurement methodology. This may suggest that any scientifically accepted method of determining average molecular weight that results in a value within the claimed range would satisfy the limitation.
      • Evidence for a Narrower Interpretation: The specification lists specific, commercially available polymers as examples, such as "Polyox WSR-303 [average molecular weight: 7,000,000]" (’780 Patent, col. 8:53-54). A party might argue that the term should be construed in light of the properties of these exemplary polymers and how their manufacturers characterized them at the time of the invention.

  • The Term: "sustained release hydrogel-forming formulation"

    • Context and Importance: This phrase defines the technological category of the invention. Its construction will determine the breadth of formulations covered by the claims. The dispute may center on whether the term implies specific structural or compositional characteristics beyond the functional result of forming a gel and sustaining release.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The patent describes the invention's objective as providing a formulation that reduces food effects by controlling the drug release rate via a hydrogel mechanism (’780 Patent, col. 1:21-30). This could support a functional interpretation where any formulation achieving this result through a hydrogel is covered.
      • Evidence for a Narrower Interpretation: Claim 1 of the ’780 Patent explicitly defines the formulation by its components: a specific type of polymer and a specific type of additive. This may support a narrower construction where the term is limited to formulations containing the recited classes of components, rather than covering any formulation that functionally performs as a hydrogel.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement for all four patents-in-suit. The basis for inducement is the allegation that Creekwood's product label will be substantially identical to the Myrbetriq® label and will instruct healthcare professionals and patients to administer the product for the treatment of overactive bladder, thereby encouraging the infringing use (Compl. ¶¶77, 95, 106). The basis for contributory infringement is the allegation that Creekwood’s generic tablets are a material part of the claimed inventions and are not staple articles of commerce suitable for substantial non-infringing use (Compl. ¶¶78, 96, 107).
  • Willful Infringement: The complaint does not explicitly use the word "willful." However, it alleges that Creekwood had knowledge of the patents-in-suit via its Paragraph IV certification (Compl. ¶7). For the more recently issued ’451 and ’189 patents, the complaint specifically alleges that "At least by the filing date of this Complaint, Creekwood will have actual knowledge" of the patents (Compl. ¶¶97, 108). These allegations, combined with the prayer for a declaration that the case is "exceptional" under 35 U.S.C. § 285, may form the basis for a later claim for enhanced damages (Compl., Prayer for Relief ¶Y).

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

  • A central issue will be one of infringement by necessity: does the regulatory requirement for Creekwood's ANDA product to be bioequivalent to Myrbetriq® tablets legally and factually compel the conclusion that its product must infringe the asserted patent claims, or could Creekwood have successfully designed a bioequivalent, non-infringing formulation?
  • The case will also turn on a question of definitional scope: how should key quantitative claim limitations, such as "average molecular weight," be construed and measured? The resolution of this issue will be critical in determining whether the specific polymer used in Creekwood's product, once revealed through discovery, falls within the boundaries of the claims.
  • An underlying evidentiary question will be one of factual proof: as the complaint is based on information and belief derived from regulatory filings, the case will depend on whether the evidence uncovered during discovery confirms that Creekwood's actual product formulation and performance characteristics align with the infringement allegations.