The parties and the court

The case is Astellas Pharma Inc. v. Alembic Pharmaceuticals Limited, No. 3:26-cv-12995 (D.N.J.), filed October 5, 2026. The plaintiffs are Astellas Pharma Inc., a Japanese corporation, and Astellas US LLC, Astellas Pharma US, Inc., Medivation LLC, and Medivation Prostate Therapeutics LLC, each a Delaware entity. The complaint alleges, on information and belief, that Alembic Pharmaceuticals Limited is an Indian corporation and that Alembic Pharmaceuticals, Inc. is a Delaware corporation based in Bedminster, New Jersey, and its wholly owned subsidiary. Astellas Pharma US holds NDA No. 213674 for Xtandi (enzalutamide) tablets, 40 mg and 80 mg, which the complaint says the FDA approved on August 4, 2020.

The patents

The complaint asserts U.S. Patents 11,839,689, titled Formulations of Enzalutamide, issued December 12, 2023; 12,161,628, titled Combination Therapy, issued December 10, 2024; and 12,502,357, titled Formulations of Enzalutamide, issued December 23, 2025. It says each issued to Astellas Pharma Inc. and Medivation Prostate Therapeutics and is listed in the Orange Book for Xtandi tablets. As the complaint quotes them, claim 1 of the '689 patent recites a pharmaceutical composition comprising a solid dispersion consisting essentially of amorphous enzalutamide and hydroxypropyl methylcellulose acetate succinate (HPMCAS); claim 1 of the '628 patent recites a method of treating prostate cancer in a patient to whom rifampin is administered by co-administering a daily dose of 240 mg of enzalutamide; and claim 1 of the '357 patent recites a method of treating prostate cancer by administering a tablet comprising a solid dispersion of amorphous enzalutamide and HPMCAS.

The notice letter and the counts

The complaint says Alembic's notice letter, dated August 21, 2026, reported that ANDA No. 221846 includes a Paragraph IV certification that the three patents are invalid, unenforceable, or not infringed, and that the plaintiffs sued within 45 days of receiving it. It alleges that the letter does not raise certain invalidity or unenforceability defenses for the '689 and '357 patents. Counts I through III allege infringement of each patent under 35 U.S.C. 271(e)(2)(A) by the ANDA submission, and allege that commercial sales would infringe, with the '628 and '357 counts adding induced infringement and the '357 count contributory infringement. The complaint also alleges, on information and belief, that Alembic copied the claimed inventions of the '689 patent.

Relief sought

The plaintiffs ask for judgments of infringement, a permanent injunction under 35 U.S.C. 271(e)(4)(B) and 283 against commercial activity before the patents expire, an order under 35 U.S.C. 271(e)(4)(A) that any FDA approval of the ANDA be effective no earlier than the patents' expiration, a finding that the case is exceptional under 35 U.S.C. 285 with attorneys' fees, and costs.

What to watch next

The docket shows waivers of service executed and filed on October 20, 2026. Watch for Alembic's answer or other response and for a scheduling order.