Alexion v. Samsung Bioepis: Federal Circuit Appeal Voluntarily Dismissed in 107 Days
Alexion Pharmaceuticals and Samsung Bioepis resolved their Federal Circuit appeal over six patents covering eculizumab — one of the world’s most valuable biologic drugs — in just 107 days. The parties jointly agreed to dismiss under Fed. R. App. P. 42(b), with each side bearing its own costs, leaving the merits unresolved on the public record.
Six eculizumab patents, one swift mutual exit at the Federal Circuit
Alexion Pharmaceuticals, Inc. and its affiliate Alexion Pharma International Operations, Ltd. filed this Federal Circuit appeal on 20 May 2024 against Samsung Bioepis Co., Ltd., asserting six US patents — US10590189B2, US9725504B2, US9732149B2, US9718880B2, US10703809B1, and US9447176B2 — all directed to eculizumab antibody compositions and related methods. The dispute centred on Samsung Bioepis’s SB12, a proposed biosimilar to Alexion’s blockbuster complement inhibitor Soliris.
The appeal was terminated on 4 September 2024, just 107 days after filing, through a voluntary dismissal agreed by both parties under Fed. R. App. P. 42(b). The court’s order reflects a mutual agreement: the proceeding is dismissed and each side bears its own costs. The public record does not specify whether the dismissal was with or without prejudice, which carries significant implications for whether Alexion could re-assert these patents in future proceedings.
The speed of resolution — roughly one-quarter of a typical Federal Circuit appeal cycle — suggests the parties reached a commercial accommodation, potentially a licensing arrangement or settlement, though nothing has been confirmed on the public record. The symmetrical cost order, with neither side recovering fees, is consistent with a negotiated exit rather than a concession by either party. What drove the agreement and whether any of the six patents remain subject to challenge or licence obligations is not disclosed publicly.
Filing to Voluntary dismissal in 107 days
107 days — resolved well before a typical Federal Circuit appeal, which averages 12–18 months
Voluntarily dismissed: what the mutual exit means for both parties
Fed. R. App. P. 42(b): a mutual appellate exit, not a merits ruling
Rule 42(b) of the Federal Rules of Appellate Procedure permits parties to dismiss an appeal by filing a signed agreement. Unlike a court-decided outcome, it carries no findings on infringement, validity, or enforceability. The court’s order here reflects exactly that: both parties agreed, the proceeding is dismissed, and costs lie where they fall. No merits determination appears in the public record.
No merits adjudicationWith or without prejudice? The public record is silent
A dismissal ‘with prejudice’ would bar Alexion from re-asserting these six patents against Samsung Bioepis on the same claims. A dismissal ‘without prejudice’ would preserve that right. The order as recorded states only ‘Voluntary dismissal’ and does not specify either condition. This ambiguity is commercially material — parties considering Samsung Bioepis’s freedom to operate with SB12 should not assume either outcome without further diligence.
Prejudice status unconfirmedAlexion exits with no adverse ruling — patents remain formally intact
Because the appeal was dismissed by agreement without a merits ruling, Alexion’s six eculizumab patents emerge from this proceeding without any court finding of invalidity or non-infringement. The patents’ enforceability is formally unchanged. Whether Alexion secured commercial consideration — royalties, a licence, or a market-entry undertaking — in exchange for agreeing to dismiss is not disclosed on the public record.
Patents formally unchallengedSamsung Bioepis avoids an adverse Federal Circuit ruling
Samsung Bioepis exits this appeal without a Federal Circuit finding of infringement against SB12. The symmetric cost order suggests neither party blinked publicly. However, the silence on prejudice and any potential licence terms means SB12’s commercial path and ongoing IP exposure remain uncertain from publicly available information. Biosimilar market entry timelines for eculizumab SB12 should be assessed against the full patent landscape, not this proceeding alone.
No infringement finding recordedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Alexion Pharmaceuticals, Inc. | Company | Biopharmaceutical innovator and complement-inhibitor IP licensor — holder of US10590189B2 and 5 related eculizumab patentsSearch in Eureka ↗ |
| Co-Plaintiff | Alexion Pharma International Operations, Ltd. | Company | Search in Eureka ↗ |
| Defendant | Samsung Bioepis Co., Ltd. | Company | South Korean biosimilar developer; maker of SB12, a proposed eculizumab biosimilar to Alexion’s SolirisSearch in Eureka ↗ |
| Plaintiff counsel | Andrew Cochran | Attorney | Counsel for Alexion Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Gerald J. Flattmann Jr. | Attorney | Counsel for Alexion Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Cahill Gordon & Reindel LLP | Law Firm | Representing Alexion Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Adam Gershenson | Attorney | Counsel for Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Defendant counsel | Alexander Robledo | Attorney | Counsel for Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Defendant counsel | Daniel Jedediah Knauss | Attorney | Counsel for Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Defendant counsel | Jonathan Davies | Attorney | Counsel for Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Defendant counsel | Michelle S. Rhyu | Attorney | Counsel for Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Defendant counsel | Orion Armon | Attorney | Counsel for Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Defendant counsel | Patrick Hayden | Attorney | Counsel for Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Defendant law firm | Cooley LLP | Law Firm | Representing Samsung Bioepis Co., Ltd.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Court of Appeals for the Federal CircuitSearch in Eureka ↗ |
Official order — verbatim text
The order records a clean procedural exit: both parties agreed, the appeal is dismissed under Fed. R. App. P. 42(b), and costs are split. The absence of any merits language — no finding on infringement, validity, or claim scope — means this verdict cannot be read as a win or loss for either side on the substantive patent questions. The symmetric cost allocation is consistent with a negotiated resolution rather than a concession. Critically, the order does not state whether the dismissal is with or without prejudice, which materially affects Alexion’s future enforcement options against Samsung Bioepis on these six patents.
US10590189B2 and five related patents — eculizumab antibody compositions and methods
The six patents at issue — US10590189B2, US9725504B2, US9732149B2, US9718880B2, US10703809B1, and US9447176B2 — collectively cover eculizumab, a humanised monoclonal antibody targeting complement protein C5. Eculizumab is the active ingredient in Soliris, used to treat rare, life-threatening conditions including paroxysmal nocturnal haemoglobinuria (PNH) and atypical haemolytic uraemic syndrome (aHUS). The patents span multiple application families filed between 2011 and 2020, suggesting a prosecution strategy designed to extend IP coverage across composition, formulation, and method-of-use claims.
Eculizumab has been among the world’s highest-revenue biologic drugs, making its patent estate one of the most commercially contested in the complement inhibitor space. A multi-patent assertion strategy of this kind is consistent with biologic originators seeking to deter or delay biosimilar entry by creating overlapping layers of IP risk. For biosimilar developers, competitors in the C5 inhibitor space, and healthcare payers tracking market entry timelines, understanding the full scope and expiry profile of these six patents — and any downstream continuation risk — is commercially critical.
Should you run an FTO against US10590189B2 and Alexion’s eculizumab patent family?
Any company developing, manufacturing, or commercialising an eculizumab biosimilar, a next-generation anti-C5 antibody, or a complement inhibitor product with structural or functional overlap with Soliris should treat this six-patent family as a priority FTO target. The voluntary dismissal in this case does not constitute a validity finding or a non-infringement determination — these patents remain in force and their claim scope has not been adjudicated on the merits in this proceeding.
PatSnap Eureka’s FTO Search Agent can map each of the six patents’ independent claims against your product’s structural and functional profile, identify prosecution history estoppel, flag continuation applications that may extend portfolio risk beyond current expiry dates, and surface inter partes review (IPR) history that may have narrowed or confirmed claim scope. For biosimilar and biologic development teams, a structured FTO across all six patents — not just the lead patent — is the defensible standard before any regulatory submission or commercial launch.
Run a freedom-to-operate analysis on US10590189B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit eculizumab and biologic biosimilar patent appeals
Cases involving Alexion’s eculizumab patent portfolio and Federal Circuit appeals in the biologic and biosimilar space, including BPCIA-related patent disputes over complement inhibitor antibodies.
What this case signals for the eculizumab biosimilar IP landscape
A swift mutual exit at the Federal Circuit over six foundational eculizumab patents raises questions every biosimilar developer and biologic IP holder should be asking.
Speed of resolution signals likely commercial settlement, not litigation fatigue
107 days is exceptionally fast for a Federal Circuit appeal. Voluntary mutual dismissals at this stage — particularly with a symmetric cost order — are typically consistent with a negotiated commercial resolution. IP teams monitoring the eculizumab biosimilar space should treat this as a potential licence signal rather than a clean clearance event.
Six-patent assertion strategy reflects Alexion’s layered eculizumab IP portfolio
Asserting six patents across multiple application families suggests Alexion’s enforcement strategy is built for depth — each patent potentially covering a different aspect of eculizumab composition or method. For biosimilar developers, this multi-patent stack means clearance on one patent does not resolve exposure across the portfolio. Comprehensive FTO analysis across all six patents is essential before commercialisation.
Alexion v Samsung — key questions answered
The Federal Circuit appeal (Case 24-1829) was voluntarily dismissed by agreement of both parties on 4 September 2024 under Fed. R. App. P. 42(b), 107 days after filing. The court ordered each side to bear its own costs. No merits ruling on the six asserted eculizumab patents was issued. The public record does not specify whether the dismissal was with or without prejudice.
Alexion asserted six patents: US10590189B2, US9725504B2, US9732149B2, US9718880B2, US10703809B1, and US9447176B2. All relate to eculizumab — a humanised anti-C5 complement inhibitor antibody — covering compositions, formulations, and therapeutic methods. The product at issue was Samsung Bioepis’s SB12, a proposed biosimilar to Alexion’s Soliris.
Not necessarily. The dismissal carries no finding of non-infringement or invalidity for any of the six asserted patents. Because the order is silent on whether the dismissal is with or without prejudice, Alexion may retain the option to reassert these patents in a new proceeding. Any FTO assessment for SB12 must be conducted against the full patent landscape, independent of this dismissal.
Rule 42(b) allows parties to voluntarily dismiss a Federal Circuit appeal by signed agreement. It is a procedural mechanism with no merits effect — the court makes no finding on infringement, validity, or claim scope. It differs from a court-ordered dismissal and typically reflects a negotiated resolution between the parties. The underlying patents remain enforceable unless separately invalidated.
The public record does not disclose the reason. The 107-day resolution — substantially faster than a typical Federal Circuit appeal — and the symmetric cost order are consistent with a negotiated commercial resolution, potentially involving licensing terms, market-entry timing agreements, or other commercial considerations. However, no settlement terms have been publicly disclosed, and this interpretation is based on circumstantial indicators only.
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