Astellas v. Creekwood: Mirabegron Patent Dispute Settles in Delaware

Introduction

A pharmaceutical patent dispute centered on one of urology’s most prescribed medications reached a negotiated resolution in the Delaware District Court. Astellas Pharma, Inc. and its affiliates filed suit against Creekwood Pharmaceuticals LLC in January 2025, asserting infringement of four patents covering mirabegron extended-release oral tablets — the active ingredient in Myrbetriq® — a blockbuster overactive bladder (OAB) treatment generating billions in annual global revenue.

Case No. 1:25-cv-00045, closed January 8, 2026, ended via stipulated dismissal without prejudice following a confidential Settlement and License Agreement. The resolution, completed in approximately 363 days, reflects a well-established pattern in Hatch-Waxman pharmaceutical patent litigation: early settlement that balances market entry timelines against royalty obligations. For patent attorneys, IP professionals, and R&D teams operating in the generic pharmaceutical space, this case offers instructive signals about portfolio defense strategy, ANDA litigation dynamics, and regulatory compliance requirements under the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (MMA).

Case Overview

The Parties

The Patents at Issue

Four U.S. patents were asserted in this action, covering formulation, dosing, and therapeutic application aspects of mirabegron extended-release oral tablets. The assertion of these patents is a key mechanism in Hatch-Waxman litigation.

• • U.S. Patent No. 10,842,780 — Extended-release formulation claims
• • U.S. Patent No. 11,707,451 — Formulation and/or therapeutic use claims
• • U.S. Patent No. 12,059,409 — Later-generation coverage, granted circa 2024
• • U.S. Patent No. 12,097,189 — Parallel late-stage patent coverage

The ‘409 and ‘189 patents, both carrying application numbers in the 18/6xx series, appear to represent continuation or continuation-in-part filings, suggesting Astellas pursued aggressive patent prosecution to extend its exclusivity window — a common innovator strategy in competitive pharmaceutical markets.

The Verdict & Legal Analysis

Litigation Timeline & Procedural History

Filed in the District of Delaware — the premier venue for Hatch-Waxman pharmaceutical patent litigation — the case proceeded at first-instance (district court) level before resolution. Delaware’s experienced judiciary, predictable procedural rules, and concentration of pharmaceutical IP precedent make it the venue of choice for innovator plaintiffs.

The case was assigned to Judge JFB (identified in document citations as Judge JFB-EGT), and concluded through Document 55 filed January 8, 2026 — a joint stipulation of dismissal. The 363-day resolution falls within the typical Hatch-Waxman window, though notably short of the 30-month regulatory stay that automatically suspends FDA ANDA approval upon timely litigation filing. This timing suggests the settlement may have included negotiated market entry provisions.

No appellate proceedings, PTAB inter partes review (IPR) petitions, or claim construction rulings are reflected in the provided case record, indicating the dispute resolved before significant substantive briefing concluded.

Outcome

The case closed via stipulated dismissal without prejudice under a confidential Settlement and License Agreement executed between Astellas and Creekwood. Key terms of the court-approved stipulation include:

• • All claims related to the four Patents-in-Suit dismissed without prejudice
• • Each party bears its own costs and attorneys’ fees
• • Court retains jurisdiction in the event the FTC or DOJ renders the settlement null and void
• • Settlement agreement to be submitted to the FTC Bureau of Competition and DOJ Antitrust Division per MMA requirements

No damages award, no injunctive relief, and no judicial determination of patent validity or infringement are on record. The “without prejudice” dismissal preserves Astellas’s right to reassert patents if the settlement is later invalidated by antitrust regulators.

Legal Significance

The MMA Regulatory Submission Requirement: The stipulation explicitly references the parties’ obligation to submit the Settlement and License Agreement to the FTC and DOJ pursuant to the Medicare Prescription Drug, Improvement, and Modernization Act of 2003. This is a mandatory disclosure in ANDA-related pharmaceutical patent settlements, designed to detect anticompetitive “pay-for-delay” arrangements. The explicit retention of court jurisdiction pending agency review is a sophisticated protective clause reflecting awareness of antitrust scrutiny.

Portfolio Depth as Leverage: The assertion of four patents — including two granted in the 2024 timeframe (the ‘409 and ‘189 patents) — illustrates how evergreening strategies through continuation filings can significantly strengthen a patent holder’s negotiating position in ANDA litigation. Defendants face escalating invalidity and non-infringement burdens as patent clusters expand.