Case Overview

The Parties

The Patent at Issue

This case centered on **U.S. Patent No. 8,759,320** (application no. US11/908575), which covers a manufacturing process for ferric carboxymaltose, the active ingredient in Injectafer®. The asserted claims — process claims 1–16, 19–21, and 23–25 — include a critical limitation requiring a “pH between 7.0 and 9.0” as part of the synthesis process. All asserted claims depend directly or indirectly from independent claim 1, making the construction of this pH limitation dispositive across the entire assertion.

• • US 8,759,320 — Manufacturing process for ferric carboxymaltose with pH limitation

Litigation Timeline & Procedural History

Biofer filed suit on **April 15, 2022**, in the Eastern District of New York. The case ran for **868 days** before final closure on August 30, 2024. The critical procedural milestone was the **Markman hearing held on August 3, 2023**, where the parties presented competing claim constructions of the disputed pH term. Following substantial briefing, the court issued its **Markman Order on March 29, 2024** (Dkt. 139) — a ruling that effectively resolved the entire infringement case without proceeding to trial. By August 27, 2024, the parties filed a joint stipulation for final judgment (Dkt. 156), and final judgment was entered on August 30, 2024.

The Verdict & Legal Analysis

Outcome

The Eastern District of New York entered **final judgment of non-infringement** in favor of Defendant Vifor on all asserted claims of U.S. Patent No. 8,759,320. No damages were awarded. The court made no findings on invalidity or unenforceability. The resolution was structured as a **stipulated final judgment** — strategically designed by both parties to preserve appellate rights while avoiding a full merits trial.

The Dispositive Claim Construction

The court’s Markman Order construed “pH between 7.0 and 9.0” to mean **”a pH maintained in the interval separating 7.0 and 9.0.”** Critically, the court adopted Vifor’s proposed construction, finding that the intrinsic evidence — the patent’s specification and prosecution history — supported the requirement that the pH range must be **maintained throughout the entire manufacturing process**, not merely achieved at discrete steps. This construction proved fatal to Biofer’s infringement case. Biofer acknowledged in the stipulation that, under this construction, it **could not establish** that Vifor’s process maintained pH within the 7.0–9.0 interval throughout the process — the precise factual predicate the claim required.

Legal Significance

This outcome reinforces a well-established but frequently underestimated principle: **process patent claims live and die by their claim construction**. The word “between” in a pH range — seemingly straightforward — became the battleground that determined whether a commercially valuable pharmaceutical manufacturing process infringed or did not. The court’s reliance on intrinsic evidence to impose a “maintained throughout” requirement reflects the Phillips v. AWH Corp. framework, where specification and prosecution history govern claim meaning over extrinsic sources. Notably, Biofer expressly **disagreed with the construction** and preserved its right to appeal to the U.S. Court of Appeals for the Federal Circuit.

Strategic Takeaways

For **Patent Holders**: Prosecution strategy must anticipate how process continuity terms will be construed. Specifications should explicitly address whether pH ranges — or analogous parametric limitations — apply at discrete steps or must be sustained continuously. Ambiguity at prosecution becomes a defendant’s asset at Markman.

For **Accused Infringers**: Vifor’s strategy — focusing Markman arguments on a single, dispositive claim term and pressing for a construction that eliminates infringement across all asserted claims — is a textbook example of efficient claim construction defense. Identifying and isolating the weakest claim limitation early can collapse an entire assertion before trial.

For **R&D Teams**: When designing pharmaceutical manufacturing processes, even minor deviations from a patented process parameter — such as pH fluctuation outside a claimed range at any stage — can be dispositive for freedom-to-operate purposes. Process documentation should map operating parameters against asserted patent claim limitations at every production stage.