Ingenus Pharmaceuticals v. Accord Healthcare: Cyclophosphamide Patent Dispute Dismissed

Introduction

A two-year pharmaceutical patent battle over stable, ready-to-use cyclophosphamide liquid formulations concluded not with a courtroom verdict, but with a negotiated exit. On April 1, 2025, the U.S. District Court for the District of Delaware closed Case No. 1:23-cv-00377 after Ingenus Pharmaceuticals, LLC, Leiutis Pharmaceuticals, LLP, and Accord Healthcare, Ltd. jointly stipulated to dismiss all claims, counterclaims, and affirmative defenses — without prejudice, and without costs to any party.

The case centered on U.S. Patent No. US10993952B2, covering stable ready-to-use cyclophosphamide liquid formulations — a clinically significant oncology drug delivery format. Filed in April 2023 and resolved through a private agreement dated March 21, 2025, the dismissal reflects a litigation strategy pivot that IP professionals and pharmaceutical patent attorneys should examine carefully. For R&D teams operating in the specialty drug formulation space, this case underscores the patent risk environment surrounding ready-to-use injectable oncology products.

Case Overview

The Parties

The Patent at Issue

This case involved U.S. Patent No. US10993952B2 (Application No. US15/551507), covering stable ready-to-use liquid cyclophosphamide formulations.

Cyclophosphamide is a widely used chemotherapy and immunosuppressant agent. Ready-to-use liquid formats eliminate the need for bedside reconstitution, offering clinical convenience and safety advantages. Patents covering such formulations are commercially high-value and frequently contested in Hatch-Waxman and related pharmaceutical litigation.

Legal Representation

Plaintiffs’ Counsel: Smith, Katzenstein & Jenkins LLP, with attorneys Chidambaram S. Iyer, Daniel Taylor, John T. Callahan, L. Roman Rachuba, Michael R. Dzwonczyk, and Neal C. Belgam

Defendant’s Counsel: Greenberg Traurig PA, with attorneys Alejandro Menchaca, Ben J. Mahon, Benjamin J. Schladweiler, Bradley P. Loren, Rajendra A. Chiplunkar, and Renée Mosley Delcollo

Both firms bring significant pharmaceutical IP litigation experience to the Delaware forum, signaling the commercial stakes involved.

Litigation Timeline & Procedural History

The case was filed on April 3, 2023, in the U.S. District Court for the District of Delaware — the nation’s most active venue for pharmaceutical patent litigation, particularly under the Hatch-Waxman Act framework and related ANDA-related disputes. Chief Judge Jennifer L. Hall presided over the matter at the district court level.

The case proceeded at the first-instance (trial) level and ran for 729 days before resolution — approximately two years from filing to closure. While no trial on the merits was reached, the duration suggests substantive pretrial proceedings, including likely claim construction briefing, discovery, and motion practice that ultimately shaped the parties’ decision to settle.

The stipulated dismissal, filed pursuant to Federal Rules of Civil Procedure 41(a)(1)(A)(ii) and 41(c), became effective upon execution of a private agreement on March 21, 2025, with the court retaining jurisdiction to enforce that agreement and resolve any disputes arising under it. The case officially closed on April 1, 2025.

Delaware’s continued dominance as the preferred forum for pharmaceutical IP disputes makes this case a relevant data point for venue strategy analysis.

The Verdict & Legal Analysis

Outcome

All claims, counterclaims, and affirmative defenses asserted by both parties were dismissed without prejudice under the terms of the March 21, 2025 agreement. No damages were awarded, no injunction was issued, and no costs or attorneys’ fees were assessed against either party. The court retained jurisdiction over the parties’ private agreement — a standard but strategically important provision that preserves enforcement mechanisms without continuing the litigation itself.

The specific terms of the underlying agreement between Ingenus, Leiutis, and Accord Healthcare were not disclosed in the public record. No damages figure was publicly reported.

Verdict Cause Analysis

The case was initiated as a straightforward patent infringement action — Plaintiffs alleged that Accord Healthcare’s cyclophosphamide liquid product infringed claims of US10993952B2. Accord, in turn, filed counterclaims — the nature of which likely included invalidity challenges and/or non-infringement defenses, as is standard in pharmaceutical patent disputes of this type.

The resolution by stipulated dismissal without prejudice — rather than with prejudice — is legally significant. A without-prejudice dismissal means neither party obtained a binding merits ruling. The patent’s validity was not adjudicated. Infringement was not found or denied. This preserves the plaintiff’s ability to re-assert the patent in future proceedings, subject to the terms of the private agreement and any release provisions therein.

The court’s retained jurisdiction clause suggests the agreement contains ongoing obligations — potentially including licensing terms, market entry timelines, or covenants not to sue — that may require judicial enforcement if breached.

Legal Significance

From a claim construction standpoint, the absence of a court ruling means no authoritative interpretation of US10993952B2’s claims was established in this proceeding. Patent holders asserting this patent in future disputes will need to develop claim construction positions without the benefit (or constraint) of a Delaware District Court interpretation.

The without-prejudice dismissal also means Accord retains its invalidity arguments. Should the agreement break down or future disputes arise over related products, previously developed invalidity positions remain available.

For pharmaceutical formulation patent litigation broadly, this case reflects a recurring pattern: high-value specialty drug patents, particularly those covering novel delivery formats of established compounds, are frequently resolved through negotiated agreements before trial — often following substantial pretrial investment by both parties.

Strategic Takeaways

For Patent Holders: Pursue formulation patents with broad independent claims and well-documented stability data. The ability to negotiate favorable agreements — even after two years of litigation — reflects the leverage that a granted, unchallenged patent provides. Ensure prosecution history does not unnecessarily narrow claim scope for future assertion.

For Accused Infringers: Early development of invalidity and non-infringement positions remains essential. The counterclaims filed by Accord likely contributed to the settlement dynamic. Companies entering the ready-to-use injectable market should conduct thorough freedom-to-operate (FTO) analyses before ANDA filing or commercial launch.

For R&D Teams: Stable ready-to-use liquid formulations of oncology drugs represent an active patent minefield. Any development program targeting this delivery format — particularly for chemotherapy agents — should include formulation patent clearance as a standard pre-development checkpoint.