IP Law Daily, PATENT—Fed. Cir.: Vifor preserves noninfringement judgment in iron-deficiency treatment patent dispute, (Sep 8, 2026)

By Mandavi Singh, LL.M,

The claimed manufacturing process required maintaining the solution’s pH between 7.0 and 9.0 throughout the oxidation reaction, a limitation Vifor’s process did not satisfy.

In a non-precedential disposition, the U.S. Court of Appeals for the Federal Circuit has affirmed a judgment that Vifor (International) AG did not infringe a Biofer S.p.A. patent covering a process used to manufacture iron-sugar complexes for treating iron deficiency. The court upheld the district court’s construction requiring the solution’s pH to remain between 7.0 and 9.0 throughout the claimed oxidation reaction. Because Biofer conceded that it could not establish infringement under that construction, the noninfringement judgment stood (Biofer S.P.A. v. Vifor [International] AG, No. 25-1005 (Fed. Cir. Sep. 3, 2026)).

Dispute. Biofer, an Italian pharmaceutical company, sued Vifor, a pharmaceutical company specializing in iron-deficiency treatments, in the federal district court in New York in 2022 for infringement of U.S. Patent No. 8,759,320 (the ’320 patent). The ’320 patent describes an improved process for producing complexes of iron and sugar that can be administered to patients to treat iron deficiency. According to the patent, earlier manufacturing methods could produce unstable or toxic complexes. Its process involves four steps: activating a sugar, complexing the activated sugar with an iron compound, purifying the resulting complex, and stabilizing it.

The dispute ultimately turned on the construction of a pH limitation governing one step of Vifor’s manufacturing process. The district court construed the limitation against Biofer and later entered a stipulated judgment of noninfringement, allowing Biofer to appeal the claim construction. The appeal concerned only the first, or oxidation, step. Claim 1 requires reacting dextrin or dextran with bromine in a solution “at a pH between 7.0 and 9.0.” Oxidation converts an aldehyde portion of the sugar into a carboxylic acid. Because oxidation at other sites can cause the sugar molecules to break down through depolymerization, controlling pH is important to selectively oxidizing the desired aldehyde end groups.

The parties disagreed over whether the claimed pH range had to be maintained throughout the oxidation reaction. Biofer argued that “between 7.0 and 9.0” merely defined a numerical range and did not require the pH to remain within that range for the entire reaction. Vifor maintained that the claim, read with the specification and prosecution history, imposed precisely that requirement.

The district court agreed with Vifor, construing the language to mean that the “pH is maintained in the interval separating 7.0 and 9.0.” Discovery subsequently showed that Vifor’s process remained within that range for approximately 90 percent of the oxidation reaction. Biofer stipulated that it could not establish infringement under the court’s construction, and the court entered judgment for Vifor.

Claim language. The Federal Circuit agreed that the pH requirement applied throughout the oxidation step. Under Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc), claim terms generally receive the meaning a skilled artisan would give them when read in the context of the claims, specification, and prosecution history.

Grammatically, the court reasoned, the phrase “in a solution at a pH between 7.0 and 9.0” modified the entire “step of reacting a sugar.” Because that step referred to the oxidation reaction as a whole, the specified pH range defined the solution’s environment for the duration of that reaction.

The specification reinforced that reading. It explained that avoiding undesirable depolymerization required maintaining the reaction pH within a specified range and expressly stated that, throughout activation, the pH was “controlled and maintained” within a fixed range, preferably between 7.0 and 9.0. Each relevant example similarly described maintaining the pH during oxidation. Citing GPNE Corp. v. Apple Inc., 830 F.3d 1365 (Fed. Cir. 2016), the court explained that a patent’s repeated and consistent characterization of a claim term can properly inform its construction.

Prosecution history. Biofer’s statements during prosecution provided additional support. To demonstrate the importance of the claimed pH interval, an inventor submitted experimental results comparing reactions maintained within different pH ranges. Biofer relied on those results to argue that operating outside the claimed range failed to prevent destructive attack on the sugar, and the court subsequently allowed the claims.

The court rejected Biofer’s contention that this construction improperly confined the claim to a preferred embodiment. Although the specification disclosed a broader pH range of 5.0 to 12.0, claim 1 expressly selected the narrower 7.0-to-9.0 range. Citing Apple Inc. v. Andrea Electronics Corp., 949 F.3d 697 (Fed. Cir. 2020), the court noted that every claim need not encompass every disclosed embodiment.

Biofer alternatively argued at oral argument that brief excursions outside the claimed range should be permissible. The court found that argument forfeited because Biofer had not advanced it below. Under Conoco, Inc. v. Energy & Environmental International, L.C., 460 F.3d 1349 (Fed. Cir. 2006), a party may not introduce a new claim-construction position on appeal.

The Federal Circuit also declined to consider Biofer’s challenge to the construction of a separate hypochlorite limitation because the stipulated noninfringement judgment did not implicate that term. Because Biofer conceded that Vifor did not infringe under the affirmed pH construction, the court affirmed the noninfringement judgment and awarded costs to Vifor.

The Case is No. 25-1005.

Judge: Reyna, J.

Attorneys: Jonathan D. Ball (Greenberg Traurig LLP) for Biofer S.P.A. Sanya Sukduang (Norton Rose Fulbright US LLP) for Vifor [International] AG.

Companies: Biofer S.P.A.; Vifor [International] AG

Cases: Patent FedCirNews