JSR Corp v. Cytiva Bioprocess: Federal Circuit Splits Decision on Protein A Chromatography Patent
JSR Corporation and JSR Life Sciences asserted US10343142B2 — covering a Protein A-derived chromatography ligand for antibody isolation — against Cytiva Bioprocess R&D AB. The Federal Circuit delivered a mixed outcome after 489 days, affirming certain aspects and reversing others, with part of the appeal also dismissed.
A Divided Federal Circuit Ruling in Bioprocess Chromatography IP
JSR Corporation and its affiliate JSR Life Sciences, LLC brought this infringement action against Cytiva Bioprocess R&D AB asserting US10343142B2, a patent covering a chromatography ligand that incorporates domain C from Staphylococcus aureus Protein A — a technology central to commercial-scale monoclonal antibody purification. The case was docketed at the Federal Circuit as No. 23-2239 and filed on August 3, 2023, following underlying district-level proceedings.
The Federal Circuit issued its decision on December 4, 2024, delivering a split outcome: AFFIRMED-IN-PART AND REVERSED-IN-PART, with the appeal also dismissed in part. This means the appellate court found some lower-court determinations to be correct and free of reversible error, while finding that other determinations could not stand and required reversal — and that certain issues were not properly before the court at the appellate stage.
A 489-day appellate timeline is consistent with Federal Circuit cases involving complex biotechnology claim construction and validity disputes. The mixed ruling suggests that neither party obtained a clean victory on appeal — JSR preserved some ground while Cytiva successfully challenged other aspects. The precise claims or issues mapped to each outcome are not fully detailed in the public docket record reviewed here, but the split decision is commercially significant for the Protein A chromatography ligand sector.
Filing to Appeal Dismissed in Part in 489 days
489 days — above average for a Federal Circuit infringement appeal
Federal Circuit splits: what the affirmed-in-part, reversed-in-part ruling means
What ‘Affirmed-in-Part, Reversed-in-Part’ means at the Federal Circuit
An affirmed-in-part and reversed-in-part ruling means the Federal Circuit found no reversible error in some of the lower tribunal’s determinations — those aspects stand — while finding legal error in other determinations, which are reversed. The court also dismissed part of the appeal, typically indicating certain issues lacked jurisdiction or were not ripe for appellate review. No single party prevailed entirely on the merits.
Mixed appellate outcomeJSR retains some positions but loses ground on reversal
JSR Corporation and JSR Life Sciences secured partial validation of their US10343142B2 positions — the affirmed portions of the lower decision remain intact and enforceable. However, the reversed portions represent a setback: some findings in JSR’s favour could not be sustained under Federal Circuit review. The patent itself is not necessarily invalidated in full; the commercial enforceability depends on which specific claims or issues were affirmed versus reversed.
Partial patent position preservedCytiva achieves partial reversal, but the fight is not over
Cytiva Bioprocess R&D AB successfully convinced the Federal Circuit to reverse at least some findings from below — a meaningful appellate win. The dismissal-in-part of the appeal also removed certain issues from the table. However, Cytiva did not achieve a full reversal; the affirmed portions of the ruling maintain legal weight against it. Further proceedings or licensing negotiations may follow depending on the scope of what was reversed.
Partial reversal securedBioprocess sector faces continued uncertainty on Protein A ligand IP
Protein A-based chromatography is the dominant platform for monoclonal antibody purification — a multi-billion-dollar commercial segment. A split Federal Circuit decision on US10343142B2 leaves the competitive landscape partially unresolved. Companies developing or supplying Protein A ligand products should monitor any remand proceedings or post-appeal activity closely, as the scope of valid and enforceable claims may still shift following this decision.
Ongoing IP risk in mAb purificationFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | JSR Corporation | Company | Bioprocess materials company — holder of US10343142B2 covering Protein A domain C chromatography ligandsSearch in Eureka ↗ |
| Co-Plaintiff | Jsr Life Sciences, LLC | Company | Search in Eureka ↗ |
| Defendant | Cytiva Bioprocess R & D, AB | Individual | Cytiva Bioprocess R&D AB — bioprocess technology developer and supplier of chromatography productsSearch in Eureka ↗ |
| Plaintiff counsel | Naveen Modi | Attorney | Counsel for JSR CorporationSearch in Eureka ↗ |
| Plaintiff law firm | Paul Hastings, LLP | Law Firm | Representing JSR CorporationSearch in Eureka ↗ |
| Defendant counsel | David M. Krinsky | Attorney | Counsel for Cytiva Bioprocess R & D, ABSearch in Eureka ↗ |
| Defendant law firm | Williams & Connolly LLP | Law Firm | Representing Cytiva Bioprocess R & D, ABSearch 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 disposition — ‘AFFIRMED-IN-PART AND REVERSED-IN-PART’ with the appeal ‘DISMISSED IN PART’ — reflects a granular, claim-by-claim or issue-by-issue appellate review. Under Federal Circuit practice, affirmance requires that the lower tribunal’s determination be free of reversible legal error; reversal requires identification of such error. The dismissal-in-part typically indicates that one or more issues were not properly preserved or lacked appellate jurisdiction. For US10343142B2, this signals a fractured but live patent position.
US10343142B2 — Protein A Domain C Chromatography Ligand for Antibody Isolation
US10343142B2 (application no. US16/189894) protects a chromatography ligand comprising domain C derived from Staphylococcus aureus Protein A, engineered for the selective isolation of antibodies. Protein A affinity chromatography is the industry-standard platform step in monoclonal antibody downstream processing, and domain C-based ligands are engineered for stability and binding performance. The patent sits within a technically demanding field requiring precise protein engineering claims.
For the bioprocess and biosimilar manufacturing sector, control over Protein A ligand IP carries substantial commercial leverage — resin suppliers and mAb manufacturers alike depend on access to high-performance affinity ligands. JSR’s assertion of this patent against Cytiva, one of the dominant players in bioprocess consumables, reflects the intensity of competition in this space. The Federal Circuit’s partial reversal introduces uncertainty that may affect licensing terms, supply agreements, and competitor product development strategies across the mAb purification market.
Should you run an FTO analysis against US10343142B2?
Any company developing, manufacturing, or supplying Protein A-based affinity chromatography ligands — particularly those incorporating or engineering variants of Staphylococcus aureus Protein A domain C — should treat US10343142B2 as an active FTO risk. The Federal Circuit’s partial affirmance means enforceable claim scope persists. Biosimilar manufacturers and CDMOs relying on third-party Protein A resins should also assess indirect infringement exposure in their downstream purification processes.
PatSnap Eureka’s FTO Search Agent enables R&D and IP teams to map claim language from US10343142B2 against product specifications and prior art in minutes. With the split Federal Circuit ruling creating a nuanced claims landscape, Eureka can help identify which specific claim elements were most likely affirmed versus reversed and flag design-around opportunities — giving your team a structured starting point for freedom-to-operate counsel before product launch or scale-up.
Run a freedom-to-operate analysis on US10343142B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit Patent Appeals in Bioprocess & Chromatography
Explore comparable Federal Circuit infringement appeals involving bioprocess chromatography, Protein A ligand technology, and antibody purification patent disputes.
What this case signals for the bioprocess chromatography IP landscape
The Federal Circuit’s split ruling in JSR v. Cytiva highlights the contested nature of Protein A chromatography ligand IP as mAb manufacturing scales globally.
Split decisions at the Federal Circuit often precede remand or further litigation
An affirmed-in-part, reversed-in-part outcome typically sends issues back for further consideration at the lower level or reshapes the litigation posture for settlement. Companies in the Protein A chromatography supply chain should track post-appeal proceedings in this case, as the remaining reversal may alter infringement or validity findings.
US10343142B2 remains at least partially enforceable — FTO exposure persists
Because the Federal Circuit affirmed at least some aspects of the lower decision, US10343142B2 retains enforceability on those points. Product teams and R&D leaders developing chromatography ligands based on Staphylococcus aureus Protein A domain C should assess their current FTO position in light of the affirmed claim scope.
JSR v Cytiva — key questions answered
The Federal Circuit issued an affirmed-in-part and reversed-in-part ruling on December 4, 2024, with the appeal also dismissed in part. The court found some lower-level determinations correct and others legally erroneous, delivering a mixed outcome for both JSR Corporation and Cytiva Bioprocess R&D AB regarding US10343142B2.
US10343142B2 covers a chromatography ligand comprising domain C from Staphylococcus aureus Protein A, used for isolating antibodies. Protein A affinity chromatography is the leading platform technology for monoclonal antibody purification in biopharmaceutical manufacturing, making this patent commercially significant for CDMOs and biopharma producers.
It suggests the patent retains enforceability on the affirmed aspects — those lower-court findings were upheld as legally sound. On the reversed aspects, prior findings in JSR’s favour no longer stand. The practical enforceability depends on which specific claims or infringement findings were affirmed versus reversed, information not fully detailed in the public docket.
A dismissal-in-part at the Federal Circuit typically indicates that certain issues raised on appeal were not properly before the court — for example, they may not have been preserved below, may have lacked appellate jurisdiction, or may have become moot. The public record does not specify which issues were dismissed in this case.
JSR Corporation and JSR Life Sciences, LLC were represented by Naveen Modi of Paul Hastings, LLP. Cytiva Bioprocess R&D AB was represented by David M. Krinsky of Williams & Connolly LLP. Both firms are prominent in Federal Circuit patent litigation.
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