Astellas Pharma Inc. et al. v. Haimen Pharma Inc. et al.

Hatch-Waxman Litigation Over Prostate Cancer Drug Xtandi®

This lawsuit is part of a broader legal strategy by Astellas Pharma to defend its blockbuster prostate cancer drug, Xtandi® (enzalutamide), from generic competition. The plaintiffs represent a coalition of operating companies and a major university, reflecting the collaborative nature of the drug's development. Astellas is a Japan-based multinational pharmaceutical company responsible for the global commercialization of Xtandi®. Co-plaintiffs Medivation LLC and its affiliates were instrumental in the drug's initial development and are now subsidiaries of Pfizer, which acquired Medivation in 2016. The Regents of the University of California is the academic institution where the foundational research leading to the drug's active ingredient, enzalutamide, was conducted, and it holds the original patents. The defendants, Haimen Pharma Inc. and its parent company SinoTherapeutics Inc., are China-based specialty pharmaceutical companies focused on developing and manufacturing complex generic drugs for the global market.

The case centers on the defendants' filing of an Abbreviated New Drug Application (ANDA) with the U.S. Food and Drug Administration (FDA), seeking permission to market a generic version of Xtandi® before the expiration of the plaintiffs' patents. This act is the basis for patent infringement litigation under the Hatch-Waxman Act. The specific patent at issue in this consolidated case is U.S. Patent No. 12,161,628. This patent, issued in December 2024, covers a method of treating prostate cancer by co-administering a specific daily dose of enzalutamide with another drug, rifampin. This type of "method-of-use" patent is a common strategy used by brand-name drug manufacturers to extend the market exclusivity of their products beyond the expiration of the original compound patents.

The litigation is proceeding in the U.S. District Court for the District of New Jersey, a prominent venue for patent infringement cases, particularly those involving pharmaceutical products under the Hatch-Waxman Act. The district is known for its experienced judiciary in patent matters and its specialized local rules designed to streamline complex patent litigation. This case is notable as it represents a key front in Astellas's multi-jurisdictional effort to protect its Xtandi® franchise, which has seen related patent challenges across Europe. The outcome of this and other related U.S. cases will significantly impact when lower-cost generic versions of Xtandi®, a critical and widely used treatment for advanced prostate cancer, become available to patients in the United States. The case has been assigned to Judge Michael A. Shipp.

As a senior patent litigation analyst, here are the key legal developments and the outcome for the patent infringement litigation Astellas Pharma Inc. et al. v. Haimen Pharma Inc. et al.

This report details the progression of a Hatch-Waxman patent infringement lawsuit concerning Astellas's blockbuster prostate cancer drug, Xtandi® (enzalutamide). The case concluded after approximately 16 months with a final dismissal, indicative of a settlement between the parties.

Key Legal Developments & Outcome

Filing and Initial Pleadings (2024 - 2025)

• Initial Complaint (2024-09-24): Astellas and its partners, including Medivation and The Regents of the University of California, filed a patent infringement lawsuit against Haimen Pharma Inc. and SinoTherapeutics Inc. in the U.S. District Court for the District of New Jersey. This action was triggered by the defendants' filing of an Abbreviated New Drug Application (ANDA) with the FDA, seeking to market a generic version of Xtandi®. The case was assigned case number 3:24-cv-09403 and Judge Michael A. Shipp.
• Consolidation (Date Varies by Case): This case was part of a broader legal strategy by Astellas to defend the Xtandi® patent portfolio. The court consolidated this case with a similar case, Astellas v. Zydus Pharmaceuticals, case number 3:24-cv-09748, for all purposes.
• Amended Complaint Asserting the '628 Patent (2025-01-03): Following the grant of U.S. Patent No. 12,161,628 on December 10, 2024, Astellas filed an amended complaint in the consolidated action to include this new patent. The '628 patent, titled "Combination therapy," covers a specific dosage regimen for co-administering enzalutamide with another drug. This is a common strategy to extend patent protection for a successful drug product.

While public records confirm Haimen Pharma was a counter-claimant, specific details regarding their answer and the substance of their counterclaims are not available in the searched materials.

Pre-Trial and Discovery Period (2025)

The case proceeded through the initial stages of litigation. However, a detailed timeline of pre-trial motions, such as motions to dismiss or for summary judgment, and specific discovery milestones is not available in the public record. Similarly, there is no indication from the available information that the case reached a Markman hearing for claim construction. The relatively short duration of the case before its resolution suggests it was likely resolved before these more advanced stages of litigation were completed.

Parallel Proceedings

No evidence was found of any Inter Partes Review (IPR) or other post-grant proceedings filed at the Patent Trial and Appeal Board (PTAB) by Haimen Pharma or SinoTherapeutics challenging the validity of the '628 patent. Astellas has been involved in numerous other litigations in the U.S. and abroad to defend its patents for Xtandi®, indicating a robust, multi-front strategy to protect its market exclusivity.

Outcome: Settlement and Dismissal (2026)

• Stipulation and Order of Dismissal (2026-01-20): The parties filed for a joint dismissal, and the court subsequently dismissed the case with prejudice. A dismissal "with prejudice" is a final judgment that prevents Astellas from re-filing a lawsuit against Haimen on the same claims.
• Implied Settlement: The dismissal with prejudice after 16 months of litigation strongly indicates the parties reached a confidential settlement agreement. This is a very common outcome in Hatch-Waxman litigation, often involving a negotiated market entry date for the generic manufacturer in exchange for acknowledging the patent's validity or infringement. The specific terms of the agreement between Astellas and Haimen, such as any potential licensed entry date or financial terms, remain confidential.

As of May 8, 2026, the case is closed and considered fully resolved. There are no pending appeals.

Based on a review of court filings and attorney profiles, the following counsel represent the plaintiffs Astellas Pharma Inc., The Regents of the University of California, and their related entities in this patent infringement action.

Lead Counsel

Attorneys from Venable LLP are serving as lead counsel, appearing pro hac vice. Their representative matters confirm extensive experience in pharmaceutical patent litigation, including prior work for Astellas concerning the same drug, Xtandi®.

• Name: Dominick A. Conde

  • Role: Lead Counsel (Of Counsel on filings)
  • Firm: Venable LLP, New York, NY
  • Note: Co-chair of Venable's Intellectual Property Division, he has previously represented Astellas and Pfizer in Hatch-Waxman litigation over the prostate cancer drug Xtandi®.

• Name: William E. Solander

  • Role: Lead Counsel (Of Counsel on filings)
  • Firm: Venable LLP, New York, NY
  • Note: As co-chair of the firm's IP Litigation – Life Sciences Group, he has deep experience in high-stakes pharmaceutical patent disputes and ANDA litigation.

• Name: Erin J.D. Austin

  • Role: Of Counsel
  • Firm: Venable LLP, New York, NY
  • Note: A patent litigator with a background as a chemist, she has specific experience in Hatch-Waxman litigation and has previously represented Astellas in the Xtandi patent litigation.

• Name: Whitney Meier Howard

  • Role: Of Counsel
  • Firm: Venable LLP, New York, NY
  • Note: A pharmaceutical and biotech patent litigator who has represented Astellas and Medivation in prior Hatch-Waxman litigations concerning the Xtandi® patents.

Local Counsel

Attorneys from the New Jersey-based firm Walsh Pizzi O'Reilly Falanga LLP serve as local counsel for the plaintiffs.

• Name: Liza M. Walsh

  • Role: Local Counsel
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, NJ
  • Note: A founding and managing partner, she is a veteran litigator with over 30 years of experience in federal court, specializing in complex commercial litigation, including intellectual property matters for major pharmaceutical companies.

• Name: Katelyn O'Reilly

  • Role: Local Counsel
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, NJ
  • Note: A partner at the firm, her practice focuses on federal and complex commercial litigation, including intellectual property and business disputes.

• Name: Christine P. Clark

  • Role: Local Counsel
  • Firm: Walsh Pizzi O'Reilly Falanga LLP, Newark, NJ
  • Note: An associate whose practice focuses on business and commercial litigation and has been recognized as "One to Watch" for patent litigation by Best Lawyers.

Defendants' Counsel of Record Not Identified in Public Filings

As of today, May 8, 2026, a diligent search of publicly available dockets and litigation records has not identified the counsel of record for defendants Haimen Pharma Inc. and SinoTherapeutics Inc. in this matter.

The case, which alleges infringement of a patent related to the prostate cancer drug Xtandi®, was filed in the District of New Jersey. An amended complaint was filed on January 3, 2025. While court filings confirm the plaintiffs' legal representation, they do not name the attorneys who have appeared on behalf of the defendants.

Docket services that list attorney appearances, such as PACER and RPX Insight, require subscriptions for access to the full docket sheet where such information would be recorded. Publicly accessible versions of the complaint and news reports about the litigation do not specify which law firm or attorneys are representing Haimen Pharma and SinoTherapeutics.

The case was consolidated with a related action (3:24-cv-09748) and, according to some records, was concluded by a stipulation of dismissal with prejudice on January 20, 2026. Typically, defense counsel would have filed a notice of appearance, an answer to the complaint, or a motion to dismiss prior to a case-concluding stipulation. However, these documents are not available in the public records reviewed.

Without access to the full court docket via PACER or a similar service, the specific attorneys representing the defendants cannot be confirmed.