Pfizer v. Alkem Laboratories: Xeljanz XR Patent Action Dismissed in 44 Days
Pfizer and affiliated entities filed an infringement action against Alkem Laboratories over generic copies of Xeljanz XR (tofacitinib citrate, 11 mg and 22 mg extended-release tablets), asserting reissue patent USRE041783E. The case was voluntarily dismissed without prejudice after just 44 days — before Alkem filed any answer — preserving Pfizer’s right to refile.
Early voluntary dismissal keeps Pfizer’s tofacitinib claims alive
Filed on 7 May 2025 in the District of Delaware before Judge Colm F. Connolly, this action saw Pfizer Inc. and four affiliated entities assert reissue patent USRE041783E against Alkem Laboratories Ltd. The patent covers tofacitinib citrate extended-release tablet formulations sold commercially as Xeljanz XR in 11 mg and 22 mg strengths — a JAK inhibitor indicated for rheumatoid arthritis and other inflammatory conditions. The case falls within the familiar ANDA litigation framework, where brand-name pharmaceutical companies seek to delay or block generic market entry.
On 20 June 2025 — just 44 days after filing — Pfizer invoked Rule 41(a)(1)(A)(i) of the Federal Rules of Civil Procedure to dismiss all claims without prejudice. The notice expressly states that Alkem had not yet served an answer or motion for summary judgment at the point of dismissal. A Rule 41(a)(1)(A)(i) dismissal is a unilateral right available to a plaintiff before the defendant responds, and it carries no preclusive effect, meaning Pfizer is free to assert the same patent claims in a future action.
The 44-day timeline and pre-answer dismissal suggest a resolution or strategic repositioning occurred rapidly — possibly a licensing discussion, a revised ANDA certification, or a decision to consolidate claims elsewhere. The public record does not disclose the underlying reason. No cost order or fee-shifting motion was filed, which is consistent with the early stage of proceedings. Whether Pfizer refiles against Alkem or focuses enforcement on other generic applicants challenging Xeljanz XR remains an open question from the public record.
Filing to Dismissed without Prejudice in 44 days
44 days — resolved before defendant answered; well below median ANDA litigation duration
Dismissed without prejudice: what Pfizer’s Rule 41 exit means for both parties
Rule 41(a)(1)(A)(i) gives plaintiff an unconditional exit
Under Rule 41(a)(1)(A)(i), a plaintiff may dismiss an action without court approval at any time before the opposing party serves an answer or motion for summary judgment. The dismissal is without prejudice as a matter of law unless the notice states otherwise. Because Alkem had not yet responded, Pfizer exercised this right unilaterally, leaving the court no discretion to impose conditions or convert the dismissal to one with prejudice.
No court approval requiredPfizer preserves full optionality to refile on USRE041783E
A without-prejudice dismissal carries no res judicata effect. Pfizer and its affiliates retain the right to assert USRE041783E against Alkem again — in Delaware or another venue — at any time before the patent expires. This outcome is commercially neutral for Pfizer in the short term: no injunction was denied, no invalidity finding was made, and no adverse claim construction entered the record. The patent’s enforceability is entirely intact.
Patent fully intactAlkem faces no judgment — but the cloud over its ANDA persists
Alkem secured no declaratory judgment of non-infringement or invalidity, meaning the 30-month stay mechanism under Hatch-Waxman may still affect its FDA approval timeline depending on when the original notice letter was sent. The dismissal without prejudice means Pfizer can reinstate infringement claims, so Alkem cannot treat this exit as a clear path to market. Strategic certainty remains absent until Pfizer either refiles or the patent expires.
No declaratory judgmentGeneric tofacitinib XR market entry remains strategically uncertain
Tofacitinib (Xeljanz) faces generic competition across multiple ANDA filers. A pre-answer dismissal without prejudice against one challenger — rather than a negotiated settlement or consent judgment — suggests the competitive dynamics around Xeljanz XR are still being resolved. Other generic applicants and market observers should monitor whether Pfizer refiles against Alkem or pivots strategy, as the outcome will affect the trajectory of tofacitinib XR genericisation more broadly.
Market entry still unresolvedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Pfizer, Inc. | Company | Global pharmaceutical innovator — holder of USRE041783E covering tofacitinib XR formulationsSearch in Eureka ↗ |
| Defendant | Alkem Laboratories, Ltd. | Company | Indian generic pharmaceutical manufacturer seeking U.S. approval for tofacitinib XR tabletsSearch in Eureka ↗ |
| Plaintiff counsel | Megan Elizabeth Dellinger | Attorney | Counsel for Pfizer, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Morris, Nichols, Arsht & Tunnell LLP | Law Firm | Representing Pfizer, Inc.Search in Eureka ↗ |
| Presiding judge | Judge Colm F. Connolly | Judge | Delaware District CourtSearch in Eureka ↗ |
Official order — verbatim text
The dismissal notice is precise in its invocation: Rule 41(a)(1)(A)(i) applies only where the defendant has not served an answer or motion for summary judgment, and the notice expressly confirms this condition is met. The without-prejudice designation is the default consequence — no court order is needed, and no adverse inference attaches to Pfizer’s claims or the validity of USRE041783E. For Alkem, the absence of any merits adjudication means it cannot rely on this proceeding to establish non-infringement or invalidity in any future action.
USRE041783E — Tofacitinib Citrate Extended-Release Tablet Formulation
USRE041783E is a United States reissue patent — a patent that was reissued by the USPTO to correct errors in or broaden the claims of an original granted patent. The reissue designation is commercially significant: reissued claims may extend coverage beyond what the original grant protected, and the reissue examination history forms part of the prosecution record that courts consider during claim construction. The patent covers tofacitinib citrate extended-release tablet formulations, which are the active pharmaceutical basis of Pfizer’s Xeljanz XR product indicated for JAK-inhibitor-mediated treatment of inflammatory diseases including rheumatoid arthritis.
For the JAK inhibitor and oral extended-release pharmaceutical formulation sectors, USRE041783E represents a meaningful enforcement asset. Reissue patents filed in ANDA proceedings carry elevated risk for generic entrants because the broadened or corrected claims may encompass formulation approaches a generic manufacturer believed were outside the original patent’s scope. With Xeljanz XR generating substantial revenue prior to generic entry, Pfizer’s multi-entity enforcement structure — spanning multiple affiliated IP holding entities — signals that the patent family will be actively defended across any ANDA filer seeking to market tofacitinib XR tablets in the United States.
Should your team run an FTO analysis against USRE041783E?
Any company holding an approved or pending ANDA for tofacitinib citrate extended-release tablets should treat USRE041783E as a live enforcement risk. The without-prejudice dismissal against Alkem does not signal Pfizer’s withdrawal from enforcement — it signals flexibility. R&D and regulatory teams developing extended-release oral JAK inhibitor formulations, even those not directly replicating Xeljanz XR, should assess whether their formulation approach falls within the reissued claim language, which may be broader than the original patent.
PatSnap Eureka’s FTO Search Agent can map USRE041783E’s claim scope against your product specifications, flag related patents in Pfizer’s tofacitinib portfolio, and surface prior art that may support invalidity arguments. For teams managing ANDA timelines and Hatch-Waxman exposure, Eureka’s litigation monitoring tools also track real-time filings against this patent, giving IP counsel early warning of any refiling by Pfizer or related entities.
Run a freedom-to-operate analysis on USRE041783E to assess your product’s exposure
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What this case signals for the ANDA pharmaceutical patent IP landscape
A 44-day pre-answer dismissal in an ANDA case rarely means the dispute is over — it often marks a strategic reset.
Pre-answer dismissals in ANDA cases are a tactical tool, not a concession
Rule 41(a)(1)(A)(i) dismissals before any defendant response preserve the plaintiff’s full legal position. For brand pharmaceutical companies, this mechanism allows rapid adjustment — whether to consolidate litigation, respond to ANDA amendments, or pivot to licensing — without creating any unfavourable precedent or weakening the patent.
Reissue patents in ANDA litigation warrant heightened FTO scrutiny
USRE041783E is a reissue patent, meaning its claims were broadened or corrected post-grant by the USPTO. Reissue patents can capture product configurations not covered by the original grant. Generic manufacturers and biosimilar developers working in the JAK inhibitor or extended-release oral formulation space should assess whether their ANDA specifications fall within the reissued claim scope.
Pfizer v Alkem — key questions answered
A without-prejudice dismissal under Rule 41(a)(1)(A)(i) means no merits ruling was made and Pfizer retains the right to refile. For Alkem’s ANDA, this creates continued uncertainty: no covenant not to sue was granted, and USRE041783E remains enforceable. Depending on the Hatch-Waxman 30-month stay clock tied to the original Paragraph IV certification, Alkem’s FDA approval timeline may still be constrained.
USRE041783E was reissued by the USPTO to correct or broaden claims in the original patent covering tofacitinib citrate extended-release formulations. Reissue patents are significant in ANDA litigation because their claims may cover formulation approaches not captured by the original grant, potentially surprising generic applicants who designed around the original patent. Courts apply standard claim construction to reissued claims, and the reissue prosecution history is part of the record.
Yes. Under Rule 41(a)(1)(A)(i), a dismissal without prejudice carries no res judicata or collateral estoppel effect. Pfizer and its affiliated plaintiffs are legally entitled to refile an infringement action asserting USRE041783E against Alkem at any time, provided the patent remains in force. The only constraint Pfizer faces is the ‘two dismissal rule’ under Rule 41(a)(1)(B), which would convert a second voluntary dismissal to one with prejudice.
Alongside Pfizer Inc., the plaintiffs include C.P. Pharmaceuticals International C.V., PF PRISM C.V., PBG Puerto Rico LLC, and PF PRISM IMB B.V. This multi-entity structure is consistent with Pfizer’s global IP holding and manufacturing arrangement for Xeljanz XR, and suggests enforcement rights for USRE041783E are distributed across multiple related legal entities — a factor relevant to any freedom-to-operate analysis.
The District of Delaware is a preferred venue for pharmaceutical patent litigation, including ANDA cases, due to its experienced judiciary and well-developed patent law. Judge Colm F. Connolly, assigned here, is a highly experienced patent jurist. Filing in Delaware is a standard strategic choice for brand pharmaceutical plaintiffs seeking predictable case management, though the pre-answer dismissal means no substantive Delaware-specific rulings were made in this matter.
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