Astellas v. Hikma: Xtandi Patent Suit Dismissed With Prejudice in 81 Days
Astellas Pharma and Medivation filed a patent infringement action against Hikma Pharmaceuticals USA in New Jersey District Court, asserting two patents covering enzalutamide (Xtandi) tablets. All claims and counterclaims were dismissed with prejudice in just 81 days, with each party bearing its own costs — a resolution pattern consistent with a confidential settlement governing generic entry terms.
Xtandi ANDA dispute settles in under three months with prejudice
On January 16, 2025, Astellas Pharma Inc., Astellas US LLC, Astellas Pharma US Inc., Medivation LLC, and Medivation Prostate Therapeutics LLC filed suit against Hikma Pharmaceuticals USA Inc. in the U.S. District Court for the District of New Jersey. The action alleged infringement of US11839689B2 and US12161628B2, two patents protecting formulations and methods of use for enzalutamide — marketed as Xtandi® in 40 mg and 80 mg tablet strengths — an androgen receptor inhibitor used to treat prostate cancer.
The case concluded on April 7, 2025, just 81 days after filing, when the court issued a dismissal order at the joint request of all parties. All of Astellas and Medivation’s infringement claims against Hikma were dismissed with prejudice, as were all of Hikma’s counterclaims. The court expressly retained jurisdiction to enforce the dismissal order and the terms of a referenced settlement agreement, confirming that a private agreement governs the resolution — including, almost certainly, conditions around Hikma’s timing and scope of generic market entry.
An 81-day resolution is notably swift for pharmaceutical patent litigation of this type, which typically spans years through Hatch-Waxman proceedings. The mutual with-prejudice dismissal bars both sides from relitigating the same claims, and the cost-sharing arrangement avoids signalling a winner. The specific terms of the settlement — particularly any authorised generic licence date — remain confidential, leaving the competitive timeline for Hikma’s enzalutamide product uncertain from the public record alone.
Filing to Dismissed with Prejudice in 81 days
81 days — well below the median ANDA patent trial timeline, suggesting early settlement
Dismissed with prejudice: what the settlement-driven order means for each party
Dismissal with prejudice signals a binding resolution
A dismissal with prejudice is a final adjudication on the merits for preclusion purposes — neither Astellas nor Hikma may re-file these specific patent claims against each other. The court’s express retention of jurisdiction to enforce the underlying settlement agreement confirms the dismissal is the public face of a private contract, likely governing commercial terms such as a licensed entry date for Hikma’s generic.
Res judicata appliesAstellas preserves Xtandi exclusivity on negotiated terms
By securing a with-prejudice dismissal tied to a settlement, Astellas and Medivation effectively control when and how Hikma enters the enzalutamide market. The patents-in-suit remain valid and enforceable — they were not adjudicated invalid. Any authorised entry date agreed in the settlement insulates Astellas from immediate generic competition while providing litigation certainty. The cost-sharing structure suggests neither party perceived a dominant litigation position.
Patents intact, entry date negotiatedHikma gains a defined path to market — at a negotiated price
Hikma avoids the risk of a preliminary injunction or an adverse validity ruling on US11839689B2 and US12161628B2 that could have delayed its ANDA product indefinitely. The settlement almost certainly grants Hikma a licence to launch at a future date, a standard Hatch-Waxman resolution mechanism. However, the with-prejudice counterclaim dismissal means Hikma cannot later seek to invalidate these patents through this avenue.
Licence likely; invalidity path closedEnzalutamide generic landscape shaped but not fully revealed
The undisclosed settlement terms leave market participants — including other ANDA filers for enzalutamide — uncertain about the competitive entry timeline. Hikma’s agreed launch date, if earlier than patent expiry, may trigger most-favoured-entry clauses in other generic licences. Competitors and investors tracking Xtandi’s exclusivity window should monitor FDA ANDA approval records and any subsequent Hikma product launch announcements for timing signals.
Settlement terms confidentialFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Astellas Pharma, Inc. | Company | Pharmaceutical IP licensor — holder of US11839689B2 and US12161628B2 (Xtandi/enzalutamide)Search in Eureka ↗ |
| Defendant | Hikma Pharmaceuticals USA, Inc. | Company | Generic pharmaceutical manufacturer seeking ANDA approval for enzalutamide tabletsSearch in Eureka ↗ |
| Plaintiff counsel | ALEXIS M MCJOYNT | Attorney | Counsel for Astellas Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Christine Clark | Attorney | Counsel for Astellas Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | ERIN AUSTIN | Attorney | Counsel for Astellas Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Katelyn O’Reilly | Attorney | Counsel for Astellas Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Liza M. Walsh | Attorney | Counsel for Astellas Pharma, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Venable LLP | Law Firm | Representing Astellas Pharma, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Walsh Pizzi O’reilly Falanga, LLP | Law Firm | Representing Astellas Pharma, Inc.Search in Eureka ↗ |
| Defendant counsel | Rebekah R. Conroy | Attorney | Counsel for Hikma Pharmaceuticals USA, Inc.Search in Eureka ↗ |
| Defendant law firm | Stone Conroy LLC | Law Firm | Representing Hikma Pharmaceuticals USA, Inc.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | New Jersey District CourtSearch in Eureka ↗ |
Official order — verbatim text
The dismissal order is notably precise in its bilateral scope — dismissing both Astellas’s infringement claims and Hikma’s counterclaims with prejudice, while explicitly retaining court jurisdiction over the parties’ settlement agreement. This language is a standard Hatch-Waxman settlement construct: it converts a private contract into a court-enforceable instrument without disclosing commercial terms. The mutual with-prejudice standard forecloses future relitigation on these patents between these parties, while the cost-sharing provision is consistent with a negotiated outcome where neither side conceded legal weakness.
US11839689B2 & US12161628B2 — Enzalutamide tablet formulations (Xtandi)
US11839689B2 (application US17/985235) and US12161628B2 (application US17/959350) both protect aspects of enzalutamide — an androgen receptor inhibitor marketed as Xtandi® — in 40 mg and 80 mg tablet form. The later application numbers and B2 grant designations indicate these are granted utility patents, likely continuation or continuation-in-part filings from earlier Xtandi patent families, extending protection into formulation and method-of-use claims beyond the compound itself.
Xtandi is among the highest-revenue prostate cancer therapeutics globally, making its patent estate a high-value enforcement target. The assertion of two separately issued patents — with distinct application numbers suggesting distinct continuation filings — reflects a layered exclusivity strategy by Astellas and Medivation. Any generic manufacturer seeking ANDA approval for enzalutamide tablets must navigate both patents, which remain valid and unadjudicated following this dismissal, raising the litigation cost and risk calculus for subsequent challengers.
Should you run an FTO against US11839689B2 and US12161628B2?
Any pharmaceutical manufacturer, contract development organisation, or formulation team working on enzalutamide tablets — whether for ANDA filing, biosimilar adjacency, or combination product development — should treat these two patents as active enforcement risks. Neither was adjudicated invalid or limited in scope during this litigation. The settlement’s confidentiality means claim scope remains fully intact for enforcement against all parties outside of Hikma’s specific licence.
PatSnap Eureka’s FTO Search Agent can map the full claim scope of US11839689B2 and US12161628B2 against your product specifications, identify the complete continuation family for both application lineages, flag co-pending applications that may issue, and surface prior art that could support an IPR or inter partes challenge. Use Eureka to benchmark your formulation against claim boundaries before committing to ANDA filing timelines.
Run a freedom-to-operate analysis on US11839689B2 to assess your product’s exposure
Run FTO in Eureka →Similar Hatch-Waxman patent cases involving enzalutamide and androgen receptor inhibitors
Related ANDA patent infringement cases in the New Jersey District Court involving Xtandi (enzalutamide) formulation patents and competing generic pharmaceutical challengers.
What this case signals for the Hatch-Waxman pharmaceutical IP landscape
Swift with-prejudice dismissals in ANDA cases consistently indicate negotiated entry dates — not patent weakness. Here is what IP teams should take away.
Early settlement preserves patent validity — a key Hatch-Waxman tactic
Astellas and Medivation avoided any court ruling on the validity of US11839689B2 and US12161628B2. By settling before claim construction or summary judgment, the patent holder maintains fully enforceable IP against all other generic challengers — not just Hikma. This is a deliberate and well-established originator strategy in pharmaceutical litigation.
Cost-sharing orders signal mutual concession — neither party dominated
When courts order each party to bear its own costs in ANDA settlements, it typically reflects a negotiated compromise rather than a clear-cut win. IP and litigation teams should treat the absence of a fee award not as litigation failure but as a signal that commercial settlement terms — likely a future launch date — were the primary consideration for both sides.
Astellas v Hikma — key questions answered
Astellas and Medivation asserted US11839689B2 (application US17/985235) and US12161628B2 (application US17/959350) against Hikma. Both patents cover formulations and methods of use for enzalutamide, marketed as Xtandi® in 40 mg and 80 mg tablets for prostate cancer treatment.
The 81-day resolution and the court’s express reference to a settlement agreement strongly suggest the parties reached a private commercial agreement, likely governing the timing and conditions of Hikma’s generic enzalutamide market entry. Hatch-Waxman cases frequently resolve via negotiated licence-date settlements before substantive litigation milestones.
The court order does not address FDA ANDA approval status. The dismissal with prejudice resolves the patent litigation between these parties only. Hikma’s ability to commercially launch its generic enzalutamide product depends on both FDA approval of its ANDA and the terms of the undisclosed settlement agreement with Astellas and Medivation.
Yes. Both patents remain valid and fully enforceable. Neither patent was adjudicated invalid, narrowed in scope, or subjected to claim construction during this case. The dismissal with prejudice applies only to the claims between Astellas, Medivation, and Hikma — leaving both patents available for enforcement against other ANDA filers and potential infringers.
When both parties agree to bear their own litigation costs, it signals a negotiated resolution where neither side acknowledged legal superiority. In Hatch-Waxman settlements, cost-sharing is common and typically reflects that the commercial settlement terms — such as a licensed generic entry date — are the primary value exchange, making a fee-shifting argument secondary to both parties’ strategic interests.
PatSnap Eureka searches patents and litigation data to answer instantly.