Introduction

In a procedurally significant development for biosimilar patent litigation, the U.S. Court of Appeals for the Federal Circuit dismissed Appeal Nos. 2024-1402 and 2024-1405 on April 12, 2024—just 73 days after filing. The case, Mylan NV and Biocon Biologics, Inc. v. Regeneron Pharmaceuticals, Inc., centered on a sweeping portfolio of 25 patents covering VEGF antagonist biologics, including compositions and methods underlying Regeneron’s blockbuster aflibercept product (marketed as Eylea).

The dismissal was not decided on the merits. Instead, the Federal Circuit concluded it lacked appellate jurisdiction because the district court’s December 27, 2023 decision had resolved fewer than all claims at issue—a foundational finality requirement for appellate review. Both the appeal and cross-appeal were dismissed, with each party bearing its own costs.

For patent litigators, biosimilar developers, and R&D teams operating in the anti-VEGF therapeutic space, this case offers critical lessons about appellate timing strategy, jurisdictional traps in complex multi-patent litigation, and the significant costs of premature appeals.

Case Overview

The Parties

Patents at Issue

The litigation involved a sweeping portfolio of **25 U.S. patents**, spanning multiple technology areas. These patents protect not just the aflibercept molecule, but its manufacturing, formulation, and delivery ecosystem.

• • US10406226B2 — VEGF antagonist formulations and methods
• • US10130681B2 — VEGF antagonist compositions
• • US9222106B2 — CHO cell integration sites and manufacturing platforms
• • Other patents covering serum-free and chemically defined cell culture media, enhanced expression and stability regions, biological contaminant detection methods, and modified chimeric polypeptides.

Litigation Timeline & Procedural History

The appeal originated from a district court decision dated December 27, 2023. Critically, that decision resolved fewer than all claims pending in the underlying litigation—a fatal procedural flaw for appellate purposes.

On February 22, 2024, the Federal Circuit issued a show cause order, signaling its concern about jurisdiction. Both parties subsequently agreed that the court lacked jurisdiction over the appeal and cross-appeal under 28 U.S.C. § 1295, which governs Federal Circuit appellate jurisdiction and requires a final judgment disposing of all claims.

The case’s 73-day lifespan underscores how quickly jurisdictional defects can terminate appellate proceedings—often before any substantive briefing on the merits occurs. The venue in the District of Columbia Circuit also reflects the complexity of tracking biosimilar patent disputes across multiple forums.

The Verdict & Legal Analysis

Outcome

Appeal Nos. 2024-1402 and 2024-1405 were dismissed. No damages were awarded. No injunctive relief was granted or denied on appeal. Each party bears its own costs—an outcome that, while facially neutral, represents a meaningful loss of momentum for the plaintiffs who initiated the appellate challenge.

Verdict Cause Analysis: The Jurisdictional Bar

The dispositive issue was appellate jurisdiction under the final judgment rule. Federal appellate courts, including the Federal Circuit, generally may only review final decisions—those that end litigation on the merits as to all parties and all claims. See 28 U.S.C. § 1291; Caterpillar Inc. v. Lewis, 519 U.S. 61 (1996).

The district court’s December 27, 2023 ruling addressed fewer than all claims in a 25-patent dispute. Without Rule 54(b) certification (which directs final judgment as to fewer than all claims) or another recognized exception, the Federal Circuit had no jurisdictional basis to proceed. The parties’ agreement on this point—reflected in their response to the show cause order—accelerated the inevitable dismissal.

This outcome is particularly notable because both the appeal and the cross-appeal were swept out. Regeneron’s cross-appeal, presumably aimed at preserving or expanding its district court position, was equally nullified by the jurisdictional defect.

Legal Significance

This case reinforces the final judgment rule’s strict application in multi-patent biosimilar litigation. When a district court issues a partial ruling in a sprawling patent case—common in BPCIA (Biologics Price Competition and Innovation Act) litigation involving dozens of patents—parties must carefully evaluate whether appellate jurisdiction has properly attached before filing.

The Federal Circuit’s issuance of a sua sponte show cause order demonstrates the court’s active gatekeeping role on jurisdictional questions. Patent litigators should treat such orders as serious warnings requiring immediate procedural reassessment.

From a precedential standpoint, this dismissal does not create binding substantive law on VEGF patent validity or infringement. However, it serves as a cautionary procedural precedent for managing appeals in complex multi-claim patent disputes.

Strategic Takeaways

For Patent Litigators:

• In multi-patent cases, map every claim to the district court’s ruling before filing a notice of appeal. Partial rulings require Rule 54(b) certification or mandamus to enable interlocutory review.
• Monitor Federal Circuit show cause orders closely—they signal jurisdictional skepticism that parties should address proactively.
• Cross-appeals carry identical jurisdictional risks; a defective main appeal can eliminate the cross-appeal entirely.

For IP Professionals & In-House Counsel:

• Biosimilar litigation under the BPCIA frequently involves staggered rulings across large patent portfolios. Build appellate timing checklists into litigation management protocols.
• Coordinate with outside counsel on whether district court decisions include explicit Rule 54(b) language before authorizing appeals.

For R&D Teams:

• Regeneron’s 25-patent portfolio across manufacturing, formulation, and clinical domains illustrates a layered IP strategy that creates multiple barriers for biosimilar entrants—even when individual patents may be challenged.

Industry & Competitive Implications

The Mylan/Biocon v. Regeneron dispute reflects the intensifying battleground around high-value biologics patent portfolios, particularly for products like aflibercept where patent exclusivity directly correlates with billions in market revenue.

Aflibercept biosimilar approvals have accelerated following FDA guidance, making Regeneron’s layered patent estate—spanning molecule, manufacturing, and formulation—a critical competitive moat. Cases like this reveal how branded manufacturers can leverage complex, multi-patent litigation to create friction in biosimilar market entry, even when appeals are ultimately dismissed on procedural grounds.

For Mylan and Biocon, the dismissal delays appellate resolution and forces a return to district court proceedings. The underlying merits—validity and infringement across 25 patents—remain unresolved, meaning substantial litigation costs continue for both parties.

Broader industry implications include heightened awareness of BPCIA patent dance procedures and the appellate jurisdiction risks inherent in litigating large biologic patent portfolios with staggered claim resolution. Licensing discussions in this space may also be influenced by the demonstrated cost and delay of protracted multi-patent litigation.