DCT

3:25-cv-13779

Astellas Pharma Inc v. Lupin Ltd

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Key Events
Amended Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 3:25-cv-13779, D.N.J., 01/09/2026
  • Venue Allegations: Venue is alleged as proper in the District of New Jersey because Defendant Lupin Pharmaceuticals, Inc. maintains a regular and established place of business in the district, and Defendant Lupin Limited is a foreign corporation not residing in any U.S. judicial district.
  • Core Dispute: Plaintiffs allege that Defendants’ filing of an Abbreviated New Drug Application (ANDA) to market a generic version of the prostate cancer drug Xtandi® constitutes infringement of three U.S. patents covering formulations of the active ingredient enzalutamide and associated methods of treatment.
  • Technical Context: The dispute centers on enzalutamide, an androgen receptor signaling inhibitor, and patented technologies designed to overcome its poor solubility and improve its oral bioavailability, as well as a patented method for dose adjustment during co-administration with other specific drugs.
  • Key Procedural History: This action was initiated under the Hatch-Waxman Act following Plaintiffs' receipt of a "Notice Letter" from Lupin, dated June 13, 2025, which advised of Lupin's ANDA filing and included a Paragraph IV certification asserting that claims of one of the patents-in-suit are invalid, unenforceable, and/or not infringed.

Case Timeline

Date Event
2012-09-11 Priority Date for ’689 and ’357 Patents
2015-08-12 Priority Date for ’628 Patent
2020-08-04 FDA approved NDA for Xtandi® tablets
2023-12-12 ’689 Patent Issued
2024-12-10 ’628 Patent Issued
2025-06-13 Lupin sent Paragraph IV Notice Letter
2025-12-23 ’357 Patent Issued
2026-01-09 Amended Complaint Filed

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

U.S. Patent No. 11,839,689 - *"Formulations of Enzalutamide"*

The Invention Explained

  • Problem Addressed: The patent's background section describes the active pharmaceutical ingredient enzalutamide as having very low aqueous solubility (’689 Patent, col. 2:19-24). This characteristic makes it difficult to achieve effective absorption when administered orally in its crystalline form, potentially limiting therapeutic efficacy (’689 Patent, col. 1:48-54).
  • The Patented Solution: The invention is a pharmaceutical composition that formulates enzalutamide in an amorphous (non-crystalline) state within a "solid dispersion" (’689 Patent, Abstract). This dispersion combines amorphous enzalutamide with a specific concentration-enhancing polymer, hydroxypropyl methylcellulose acetate succinate (HPMCAS), which improves the drug's solubility, absorption, and dissolution stability, allowing for higher bioavailability from an oral tablet (’689 Patent, col. 2:19-27).
  • Technical Importance: This formulation technology enables the development of a solid oral dosage form (a tablet) for a poorly soluble drug, which can provide more consistent and effective drug exposure compared to crystalline forms and may allow for more convenient dosing regimens (’689 Patent, col. 2:39-42).

Key Claims at a Glance

  • The complaint asserts infringement of at least Claim 1 (’689 Patent, Compl. ¶48).
  • The essential elements of independent Claim 1 are:
    • A pharmaceutical composition
    • comprising a solid dispersion
    • consisting essentially of amorphous enzalutamide and hydroxypropyl methylcellulose acetate succinate
  • The complaint does not explicitly reserve the right to assert dependent claims for the ’689 Patent, but notes that certain dependent claims specify the formulation is a tablet (Compl. ¶48).

U.S. Patent No. 12,161,628 - *"Combination Therapy"*

The Invention Explained

  • Problem Addressed: The patent addresses a drug-drug interaction issue. When enzalutamide is co-administered with a "strong CYP3A4 inducer" such as rifampin, the inducer speeds up the metabolism of enzalutamide in the body. This interaction decreases the plasma concentration of enzalutamide, which could reduce its therapeutic effect (’628 Patent, col. 2:2-6).
  • The Patented Solution: The patent discloses a specific method to counteract this effect. It claims a method of treating prostate cancer in a patient who is also taking rifampin, which involves "co-administering to the patient a daily dose of 240 mg of enzalutamide" (’628 Patent, cl. 1). This represents an increased dose from the standard 160 mg daily dose, intended to maintain therapeutic plasma concentrations despite the increased metabolism (’628 Patent, col. 2:7-14).
  • Technical Importance: This invention provides a clinically applicable dosing strategy to manage a significant drug-drug interaction, allowing patients to continue receiving effective enzalutamide therapy even when they must take a concurrent medication that would otherwise compromise its efficacy.

Key Claims at a Glance

  • The complaint asserts infringement of at least Claim 1 (’628 Patent, Compl. ¶64).
  • The essential elements of independent Claim 1 are:
    • A method of treating prostate cancer
    • in a patient to whom rifampin is administered
    • comprising co-administering to the patient a daily dose of 240 mg of enzalutamide
  • The complaint does not explicitly reserve the right to assert dependent claims for the ’628 Patent.

U.S. Patent No. 12,502,357 - *"Formulations of Enzalutamide"*

Technology Synopsis

  • This patent addresses the same technical problem as the ’689 Patent: the poor oral bioavailability of enzalutamide. The claimed solution is a method of treating prostate cancer by administering the specific formulation covered by the ’689 Patent. It claims the method of using a tablet that comprises a solid dispersion of amorphous enzalutamide and HPMCAS to treat prostate cancer (’357 Patent, Abstract, cl. 1).

Asserted Claims

  • The complaint asserts infringement of at least Claim 1 (Compl. ¶90).

Accused Features

  • The complaint alleges that Lupin’s proposed generic tablets will comprise the claimed solid dispersion and that their FDA-approved labeling will instruct and direct their use for the treatment of prostate cancer, thereby infringing this method-of-use patent (Compl. ¶¶93-94, 96).

III. The Accused Instrumentality

Product Identification

  • Lupin's proposed generic enzalutamide tablets in 40 mg and 80 mg dosage strengths, for which Lupin filed ANDA No. 220390 with the U.S. Food and Drug Administration (FDA) (Compl. ¶39).

Functionality and Market Context

  • The complaint alleges that Lupin's generic products are generic versions of Plaintiffs' Xtandi® tablets and are intended for the same medical indications, including the treatment of castration-resistant prostate cancer and other forms of prostate cancer (Compl. ¶¶39-40). The complaint alleges that Lupin's product, if approved, will contain "a pharmaceutical composition comprising a solid dispersion consisting essentially of amorphous enzalutamide and HPMCAS" (Compl. ¶53). The complaint further alleges that the proposed product labeling for Lupin's generic will substantially copy the instructions for Xtandi® tablets, including directing co-administration of a 240 mg daily dose for patients also receiving rifampin (Compl. ¶66). The complaint provides the chemical structure of enzalutamide, the active ingredient in the accused product (Compl. ¶25).

IV. Analysis of Infringement Allegations

U.S. Patent No. 11,839,689 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a pharmaceutical composition Lupin's proposed generic products are pharmaceutical compositions in tablet form. ¶39, ¶50 col. 3:6-9
comprising a solid dispersion Lupin's generic product is alleged to contain a solid dispersion formulation. ¶53 col. 4:48-50
consisting essentially of amorphous enzalutamide The solid dispersion in Lupin's product is alleged to consist essentially of amorphous enzalutamide. ¶53 col. 1:48-54
and hydroxypropyl methylcellulose acetate succinate The solid dispersion in Lupin's product is alleged to contain HPMCAS. ¶53 col. 12:40-44
  • Identified Points of Contention:
    • Scope Questions: The infringement analysis may turn on the claim term "consisting essentially of." A key question will be whether any additional, unlisted components in Lupin's solid dispersion, if present, materially affect the basic and novel properties of the claimed invention (i.e., enhanced solubility and bioavailability). The complaint alleges Lupin "copied the claimed invention," which suggests a belief that no such materially affecting components exist (Compl. ¶51).
    • Technical Questions: A factual question will be the precise composition and properties of Lupin's proposed generic product. Discovery will be required to determine if the enzalutamide in Lupin's product is in the "amorphous" state as required by the claim and to identify all other components of the solid dispersion.

U.S. Patent No. 12,161,628 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A method of treating prostate cancer Lupin’s proposed labeling for its generic product will allegedly direct its use for treating prostate cancer. ¶66 col. 2:28-34
in a patient to whom rifampin is administered Lupin’s proposed labeling will allegedly identify rifampin as a drug that interacts with enzalutamide and direct a specific course of action for patients receiving it. ¶66 col. 2:2-6
comprising co-administering to the patient a daily dose of 240 mg of enzalutamide. Lupin's proposed labeling will allegedly instruct physicians to prescribe, and patients to take, a daily dose of 240 mg of enzalutamide when co-administered with rifampin. ¶66 col. 2:7-14
  • Identified Points of Contention:
    • Scope Questions: The dispute will likely focus on the requirements for induced infringement. A primary legal question will be whether the specific instructions and warnings in Lupin's proposed product label constitute active encouragement sufficient to establish specific intent to induce infringement by physicians and patients.
    • Technical Questions: An evidentiary question will be the exact language of Lupin's proposed product label submitted to the FDA. The court will need to analyze this language to determine if it instructs, encourages, or merely informs physicians about a possible dosing adjustment, which could impact the finding of intent.

V. Key Claim Terms for Construction

For the ’689 Patent

  • The Term: "consisting essentially of"
  • Context and Importance: This transitional phrase is critical for defining the scope of the claimed solid dispersion. Unlike "comprising," which is open-ended, "consisting essentially of" limits the invention to the specified ingredients (amorphous enzalutamide and HPMCAS) and those that do not materially affect the "basic and novel properties" of the invention. Practitioners may focus on this term because the infringement determination will depend on whether any other excipients in Lupin's solid dispersion are found to materially alter the claimed enhanced solubility and bioavailability.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent describes combining the solid dispersion with numerous other excipients like fillers, disintegrants, and lubricants to form a final tablet (e.g., ’689 Patent, col. 19:20-50). A party could argue this shows the patentee's intent was for the "solid dispersion" itself to be a specific core component, and that only ingredients within that core component are subject to the "consisting essentially of" limitation, not other excipients in the overall tablet.
    • Evidence for a Narrower Interpretation: The "Detailed Description" repeatedly emphasizes the two-component system of amorphous drug and concentration-enhancing polymer as the solution to the technical problem (’689 Patent, col. 3:39-41). A party could argue that the "basic and novel properties" are solely derived from this specific combination and that the introduction of any other substance into the dispersion itself would materially alter those properties, thus supporting a narrow construction that permits only trace impurities.

For the ’628 Patent

  • The Term: "co-administering"
  • Context and Importance: This term is central to the claimed method of treatment. Its definition determines the timeframe and relationship required between the administration of rifampin and the claimed 240 mg dose of enzalutamide. Practitioners may focus on this term because its construction will define the scope of the infringing act that Lupin is accused of inducing.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification provides an explicit and broad definition, stating that "Co-administration" means administration in any manner in which the pharmacological effects... overlap in the patient at the same time" and clarifies that it "does not require that both agents be administered in a single pharmaceutical composition, in the same dosage form, by the same route of administration, or for the same length of time" (’628 Patent, col. 2:15-22). This language strongly supports a broad interpretation that would encompass a patient on a course of rifampin therapy who is then prescribed the claimed dose of enzalutamide.
    • Evidence for a Narrower Interpretation: The patent does not appear to offer intrinsic evidence that would support a narrower interpretation. The explicit definition provided in the specification is unusually clear and expansive, leaving little room for an argument that "co-administering" requires, for example, simultaneous intake of the two drugs.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges induced infringement of the ’628 and ’357 Patents under 35 U.S.C. § 271(b). The allegations are based on the assertion that Lupin’s proposed product labeling will instruct and encourage physicians and patients to use the generic product in the manner claimed by these method patents (Compl. ¶¶65-66, 95-96). The complaint also alleges contributory infringement of the ’357 Patent under § 271(c), stating that Lupin's product is especially made for an infringing use and is not a staple article of commerce (Compl. ¶102).
  • Willful Infringement: The complaint alleges that Lupin had pre-suit knowledge of all three patents-in-suit. For the ’689 and ’628 Patents, knowledge is alleged based on their listing in the FDA's Orange Book and Lupin's own notice letter (Compl. ¶¶55, 61). For the ’357 Patent, knowledge is alleged as of at least January 7, 2026 (Compl. ¶87). The complaint asserts that Lupin's infringement will be performed with knowledge and intent, and it seeks a declaration that the case is "exceptional" under 35 U.S.C. § 285 (Compl. ¶¶70-71, 103; Prayer for Relief ¶E).

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

  • A core issue will be one of compositional scope: For the ’689 and ’357 Patents, can the term "consisting essentially of," which describes the solid dispersion, be interpreted to allow for other excipients within that dispersion, or does it strictly limit the dispersion to amorphous enzalutamide and HPMCAS? The outcome will depend on whether any additional components in Lupin's product are found to materially alter the claimed properties of enhanced bioavailability.
  • A second central issue will be one of induced infringement: For the ’628 and ’357 Patents, does the specific language in Lupin’s proposed FDA label constitute active encouragement to perform the patented methods, thereby demonstrating the specific intent required for inducement, or does it merely convey information without amounting to a direction to infringe?
  • A key evidentiary question will be one of technical and factual correspondence: Does Lupin's ANDA product, as formulated, literally contain a "solid dispersion" with "amorphous enzalutamide" as those terms are defined in the patents, and does its proposed label literally instruct the specific dosing regimen claimed in the ’628 patent?