Cytiva v. JSR Corporation: Federal Circuit Splits Decision on Protein A Chromatography Patent
Cytiva Bioprocess R&D AB brought this infringement action against JSR Corporation and JSR Life Sciences LLC over US10875007B2, covering a chromatography ligand derived from Staphylococcus aureus Protein A domain C for antibody isolation. After 497 days, the Federal Circuit issued a mixed ruling — affirming in part and reversing in part — a result that leaves both parties with partial victories and continued commercial uncertainty.
A Split Federal Circuit Ruling Over Bioprocess Chromatography IP
Cytiva Bioprocess R&D AB, a leading bioprocess technology company and holder of US10875007B2, initiated this infringement action against JSR Corporation and its affiliate JSR Life Sciences LLC. The patent at issue claims a chromatography ligand based on domain C of Staphylococcus aureus Protein A, a critical affinity chromatography technology widely used in the purification of monoclonal antibodies for biopharmaceutical manufacturing. The appeal was docketed at the Federal Circuit on July 26, 2023.
On December 4, 2024, the Federal Circuit issued an order affirming-in-part and reversing-in-part the underlying decision, while also dismissing a portion of the appeal. This mixed outcome suggests the appellate court found merit in some of JSR’s challenges to the lower tribunal’s findings while sustaining other aspects in Cytiva’s favour. The partial dismissal further limits the scope of the final appellate record, meaning certain issues may not have been adjudicated on the merits.
The 497-day appellate timeline is consistent with technically complex biotech IP disputes before the Federal Circuit, where claim construction and validity arguments over highly specialised protein engineering technology demand extended briefing. The public record does not disclose the specific claims affirmed or reversed, leaving the precise commercial impact on both parties’ freedom to operate and enforcement posture uncertain pending any further proceedings or remand activity.
Filing to Appeal Dismissed in Part in 497 days
497 days from filing to Federal Circuit decision — above average for an appeal-level IP proceeding
Federal Circuit affirms in part, reverses in part: what the split ruling means
What ‘Affirmed-in-Part, Reversed-in-Part’ means at appellate level
A split Federal Circuit ruling means the appellate court found no reversible error in certain portions of the lower decision — those portions stand — while identifying legal or factual error in others, which are reversed. This is neither a clean win nor a clean loss for either party. The reversed portions may be remanded for further proceedings, and the partial dismissal signals some grounds were not cognisable at this appellate stage.
Mixed appellate dispositionCytiva retains partial validation but faces reversed findings
The affirmance of certain aspects of the lower decision provides Cytiva with a degree of appellate validation for its enforcement position under US10875007B2. However, the reversal of other portions weakens the full scope of the relief or validity findings Cytiva sought. Depending on which claims or issues were reversed, the patent’s enforceability against JSR’s specific Protein A chromatography products may be materially narrowed.
Partial patent survives challengeJSR achieves partial reversal — exposure reduced but not eliminated
JSR Corporation and JSR Life Sciences secured a reversal of at least some findings from below, suggesting the Federal Circuit accepted one or more of their substantive arguments — potentially on claim construction, validity, or infringement scope. The partial dismissal of the appeal further limits Cytiva’s ability to press all asserted grounds. However, the affirmed portions mean JSR’s exposure under the patent has not been fully extinguished at this stage.
Partial appellate win for challengerMixed ruling sustains uncertainty across the antibody purification IP landscape
Protein A affinity chromatography is a near-universal step in monoclonal antibody manufacturing, making US10875007B2 commercially significant across the biopharmaceutical supply chain. A split Federal Circuit ruling prolongs uncertainty for competitors, CMOs, and mAb manufacturers relying on domain C-based ligands. Parties with product lines adjacent to JSR’s offerings should monitor any remand proceedings closely, as the final scope of valid and infringed claims remains unsettled.
mAb manufacturing IP risk persistsFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Cytiva Bioprocess R & D, AB | Individual | Bioprocess technology company — holder of US10875007B2, Protein A chromatography ligand patentSearch in Eureka ↗ |
| Defendant | JSR Corporation | Company | Japanese specialty materials and life sciences company with chromatography resin product linesSearch in Eureka ↗ |
| Co-Defendant | Jsr Life Sciences, LLC | Company | Search in Eureka ↗ |
| Plaintiff counsel | David M. Krinsky | Attorney | Counsel for Cytiva Bioprocess R & D, ABSearch in Eureka ↗ |
| Plaintiff law firm | Williams & Connolly LLP | Law Firm | Representing Cytiva Bioprocess R & D, ABSearch in Eureka ↗ |
| Defendant counsel | Eric William Dittmann Esq. | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Defendant counsel | Hiroyuki Hagiwara | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Defendant counsel | Isaac S. Ashkenazi Esq. | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Defendant counsel | Michael Wolfe | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Defendant counsel | Naveen Modi | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Defendant counsel | Phillip W. Citroen | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Defendant counsel | Stephen Blake Kinnaird | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Defendant law firm | Paul Hastings Foreign Law Joint Enterprise | Law Firm | Representing JSR CorporationSearch in Eureka ↗ |
| Defendant law firm | Paul Hastings LLP | Law Firm | Representing JSR CorporationSearch in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Court of Appeals for the Federal CircuitSearch in Eureka ↗ |
Official order — verbatim text
The Federal Circuit’s order — ‘AFFIRMED-IN-PART AND REVERSED-IN-PART’ combined with a partial appeal dismissal — reflects a technically granular review of the proceedings below. Appellate affirmance applies the deferential standard of review to factual findings (clear error) and de novo review to legal conclusions such as claim construction. The reversal of certain aspects indicates the panel identified at least one reversible legal error or unsupported factual finding in the lower decision. The partial dismissal suggests one or more appellate grounds lacked jurisdictional basis or were procedurally foreclosed, narrowing the issues available for potential remand.
US10875007B2 — Protein A domain C chromatography ligand for antibody isolation
US10875007B2, filed under application number US16/443600, protects a chromatography ligand comprising domain C of Staphylococcus aureus Protein A, engineered for high-efficiency isolation of antibodies. Protein A affinity chromatography exploits the natural binding affinity of Protein A’s immunoglobulin-binding domains — including domain C — for the Fc region of IgG antibodies, enabling highly selective capture steps in biopharmaceutical downstream processing. The patent’s claims are positioned in the competitive space between naturally occurring Protein A variants and engineered ligands optimised for alkaline stability and resin longevity.
Strategically, US10875007B2 represents a core asset in Cytiva’s position within the affinity chromatography resin market, where Protein A-based resins command premium pricing and are embedded deeply in validated GMP manufacturing processes. JSR’s entry into this space with its competitive chromatography resin products — marketed under the Amsphere brand — made conflict with Cytiva’s patent portfolio commercially foreseeable. The patent’s enforceability directly affects the competitive dynamics among the small number of global suppliers capable of manufacturing GMP-grade Protein A resins at biopharmaceutical scale.
Should your team run an FTO against US10875007B2?
Any company developing, manufacturing, or commercialising Protein A affinity chromatography resins — particularly those using domain C or structurally related immunoglobulin-binding domain variants — should assess freedom-to-operate against US10875007B2 and its patent family. The Federal Circuit’s split ruling means the enforceable claim scope is not yet fully settled, but the affirmed portions retain legal force. Contract manufacturing organisations running antibody purification processes with third-party resins should also assess whether their supplier agreements adequately allocate patent infringement risk.
PatSnap Eureka’s FTO Search Agent can map the claim landscape of US10875007B2 against your specific ligand chemistry and manufacturing process parameters, identifying design-around opportunities and flagging continuation applications that may extend the patent family’s reach. Given the ongoing appellate history of this asset, Eureka’s litigation monitoring layer can alert your team to any remand decisions or new filings that would materially affect your FTO conclusions — enabling proactive rather than reactive IP strategy.
Run a freedom-to-operate analysis on US10875007B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit appeals in Protein A and bioprocess chromatography IP
Cases involving Protein A affinity chromatography patents at the Federal Circuit, including ligand structure claims and antibody purification technology disputes.
What this case signals for the bioprocess chromatography IP landscape
A Federal Circuit split on Protein A ligand patents has sector-wide implications for mAb manufacturers, CMOs, and resin suppliers.
Protein A chromatography remains a high-stakes patent enforcement target
US10875007B2 sits at the centre of one of biopharmaceutical manufacturing’s most critical unit operations. Cytiva’s willingness to pursue Federal Circuit appeals against a well-resourced competitor like JSR confirms that Protein A ligand IP is actively defended. Any company sourcing or developing domain C-based affinity resins should treat this patent family as a live enforcement risk.
Split Federal Circuit rulings typically signal remand activity — monitor closely
An affirmed-in-part, reversed-in-part outcome with a partial dismissal frequently precedes remand to the lower tribunal for further findings. Companies that supply or use Protein A chromatography resins in antibody purification workflows should watch for any remand decision, which may redefine the enforceable claim scope of US10875007B2 and alter freedom-to-operate assessments.
AB v JSR — key questions answered
The Federal Circuit issued an affirmed-in-part and reversed-in-part ruling on December 4, 2024, in Case 23-2194. The court upheld certain aspects of the lower decision concerning US10875007B2 while reversing others. A portion of the appeal was also dismissed. The precise claims or issues affirmed and reversed are not specified in the public docket record.
US10875007B2 covers a chromatography ligand comprising domain C derived from Staphylococcus aureus Protein A, used for antibody isolation. Protein A affinity chromatography is a standard capture step in monoclonal antibody manufacturing, and domain C-based ligands are used to selectively bind the Fc region of IgG antibodies. The patent is assigned to Cytiva Bioprocess R&D AB.
Protein A affinity chromatography is a near-universal purification step for monoclonal antibodies, a product class generating hundreds of billions in annual pharmaceutical revenue. Patents covering engineered Protein A domain variants — including domain C — directly affect which suppliers can manufacture competitive chromatography resins at GMP scale. US10875007B2 is therefore a commercially critical asset affecting multiple global resin suppliers and their mAb manufacturing customers.
An affirmed-in-part, reversed-in-part ruling means the Federal Circuit upheld some aspects of the lower decision while rejecting others. The affirmed portions of the ruling retain legal effect and could support continued enforcement against JSR. The reversed portions reduce the scope of Cytiva’s position as established below. Depending on what was reversed — infringement findings, validity holdings, or damages — JSR’s residual exposure under the patent may differ significantly from the original lower court outcome.
The Federal Circuit dismissed a portion of the appeal as reflected in the Basis of Termination. Partial dismissals at the Federal Circuit typically occur where certain issues lack appellate jurisdiction — for example, where interlocutory orders are not yet final — or where a party failed to preserve specific arguments below. The public record in Case 23-2194 does not specify which grounds were dismissed, but the effect is to narrow the issues that received merits adjudication.
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