A Delaware district court has dealt a significant blow to Astellas Pharma by invalidating a crucial patent for their blockbuster urinary incontinence drug Myrbetriq (mirabegron). The ruling challenges the company's efforts to maintain market exclusivity for the medication, which has become one of their leading revenue generators.
Patent Decision Impact and Market Status
The invalidated patent (US Patent No. 10,842,780) covers extended-release formulations of mirabegron and was set to provide protection until 2030. Myrbetriq, approved in the US since 2012, has shown strong market performance, with worldwide revenues reaching 188 billion yen (approximately $1.35 billion) in the last fiscal year, representing a nearly 10% growth.
The medication, also marketed as Betanis and Betmiga in certain regions, is an extended-release selective β3-adrenoceptor agonist used to treat overactive bladder with symptoms including urinary incontinence, urgency, and frequency.
Generic Competition Landscape
While several companies, including Zydus Cadila and Lupin Labs, have already received approval for generic versions of mirabegron, immediate market entry appears unlikely. Astellas has announced plans to appeal the verdict to the Court of Appeals for the Federal Circuit (CAFC), making any generic launch "at-risk" - potentially exposing manufacturers to damages if the appeals court favors Astellas.
The drug remains protected by patents covering crystal forms and usage methods until May 2024, though these were subject to previous litigation. Astellas maintains that they do not anticipate immediate generic competition and have not adjusted their financial forecasts for the fiscal year ending March 31, 2024.
Broader Commercial Challenges
This patent setback is part of a larger series of commercial challenges facing Astellas. The company recently lost a legal battle to prevent Pfizer's Hospira unit from launching a generic version of Lexiscan (regadenoson injection), their stress agent with approximately $650 million in US sales.
More significantly, Astellas faces the upcoming patent expiration of their highest-grossing product, the prostate cancer therapy Xtandi (enzalutamide), in the US market by 2027. Xtandi, developed in partnership with Pfizer, generated substantial revenue of 661 billion yen ($4.75 billion) in the last fiscal year, making its patent expiration a critical concern for the company's future financial performance.
