In re: BAC IP B.V. — Federal Circuit Affirms Unpatentability of Single-Domain Anti-IgG Antibody
BAC IP B.V., represented through Thermo Fisher Scientific, appealed a USPTO unpatentability determination for US16/282082, covering single-domain antigen-binding proteins that bind mammalian IgG. The Federal Circuit affirmed in full — finding no reversible error — closing the appeal after 378 days.
Federal Circuit closes single-domain antibody patent bid after USPTO rejection stands
BAC IP B.V. filed appeal case 24-2124 at the Court of Appeals for the Federal Circuit on 23 July 2024, challenging the United States Patent and Trademark Office’s determination that patent application US16/282082 (published as US20190177434A1) was unpatentable. The application claims single-domain antigen-binding proteins — a class of engineered antibody fragments — that specifically bind mammalian immunoglobulin G (IgG). Thermo Fisher Scientific appeared as plaintiff law firm, suggesting commercial interest in the underlying technology.
The Federal Circuit issued its order on 5 August 2025, affirming the USPTO’s unpatentability finding without reversal or remand. The court’s standard disposition — ‘AFFIRMED’ — signals that the panel found no reversible legal or factual error in the USPTO’s analysis. The affirmed basis of termination is ‘Unpatentable’, meaning the application claims were held to fail one or more statutory patentability requirements, most likely novelty or non-obviousness given the prior art-dense single-domain antibody field.
The 378-day duration from filing to disposition falls within the normal range for Federal Circuit patent appeals, suggesting no unusual procedural complications. The public record does not disclose the specific §102 or §103 grounds underlying the USPTO rejection, nor whether BAC IP B.V. exhausted all post-grant options before appeal. With affirmance, the path to patent protection for these specific claims in the United States is effectively closed unless BAC IP pursues continuation or claim-amended re-examination strategies.
Filing to Unpatentable in 378 days
378-day appeal — typical Federal Circuit patent appeals resolve in 12–24 months
Federal Circuit affirms: what the unpatentability ruling means for both parties
Affirmance means the USPTO’s rejection survives appellate scrutiny
An ‘AFFIRMED’ disposition at the Federal Circuit means the appellate panel reviewed the USPTO’s unpatentability finding and identified no reversible legal error. The lower tribunal’s decision — that the claimed single-domain antigen-binding proteins fail to meet patentability requirements — now stands as final at this level. No remand was ordered, meaning the USPTO is not required to reconsider.
No reversible error foundBAC IP B.V. loses US patent protection for these specific claims
With affirmance, BAC IP B.V.’s application US16/282082 cannot proceed to grant as filed. The company retains no enforceable US patent rights over the rejected claims. Future protection — if pursued — would require a new application with materially amended claims, a continuation strategy, or seeking protection in non-US jurisdictions where parallel applications may still be pending.
US patent bid closedUSPTO’s unpatentability position fully vindicated at appellate level
The USPTO, defended by acting counsel Farheena Yasmeen Rasheed, successfully defended its rejection at the highest domestic patent appeals court. Affirmance by the Federal Circuit is the strongest available validation of an agency patentability determination short of Supreme Court review. The bar for BAC IP to revive these claims in US proceedings is now effectively prohibitive.
Agency rejection upheldSingle-domain antibody IP space remains contested; competitors face reduced blocking risk
Affirmance of unpatentability removes a potential blocking patent from the single-domain antibody sector — a space of growing commercial importance in diagnostics and therapeutics. Competitors developing anti-IgG single-domain proteins may find this outcome supportive of freedom-to-operate arguments. Thermo Fisher Scientific’s involvement suggests downstream commercial stakes extend beyond BAC IP B.V. itself.
Reduced blocking patent riskFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | In re: BAC IP B.V. | Individual | Biotechnology IP entity — holder of single-domain anti-mammalian IgG antibody application US16/282082Search in Eureka ↗ |
| Defendant | DERRICK BRENT, Acting Under Secretary of Commerce for Intellectual Property and Acting Director of the United States Patent and Trademark Office | Individual | Acting Director of the USPTO; respondent defending agency unpatentability determination on appealSearch in Eureka ↗ |
| Plaintiff counsel | Stephen G. Whiteside Senior | Attorney | Counsel for In re: BAC IP B.V.Search in Eureka ↗ |
| Plaintiff law firm | Thermo Fisher Scientific | Law Firm | Representing In re: BAC IP B.V.Search in Eureka ↗ |
| Defendant counsel | Farheena Yasmeen Rasheed | Attorney | Counsel for DERRICK BRENT, Acting Under Secretary of Commerce for Intellectual Property and Acting Director of the United States Patent and Trademark OfficeSearch 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 — ‘THIS CAUSE having been considered, it is ORDERED AND ADJUDGED: AFFIRMED’ — is a final merits disposition confirming that the USPTO’s unpatentability determination contained no reversible error. At the Federal Circuit, affirmance signals the panel applied the appropriate standard of review — typically de novo for legal questions of patentability and substantial evidence for factual findings — and found neither basis for reversal. The terse order form is consistent with affirmances issued without separate written opinion, suggesting the panel found the appeal straightforward on the record before it.
US20190177434A1 — Single-domain antigen-binding proteins targeting mammalian IgG
US application US16/282082, published as US20190177434A1, covers single-domain antigen-binding proteins — commonly known as nanobodies or VHH domains — engineered to bind mammalian IgG antibodies. Single-domain antibodies are a structurally distinct class derived from camelid heavy-chain-only antibodies, valued for their small size, stability, and high specificity. The application’s claims target the anti-IgG binding function, which has direct relevance to secondary antibody reagents used across immunoassay, western blotting, and flow cytometry platforms.
The anti-IgG single-domain antibody space is commercially significant, particularly for research reagent manufacturers and diagnostic developers seeking to replace conventional polyclonal secondary antibodies with more reproducible, recombinant alternatives. The USPTO’s unpatentability finding — upheld by the Federal Circuit — suggests the claimed proteins were anticipated or rendered obvious by prior art in the nanobody field. For competitors, this outcome may support FTO arguments for anti-IgG single-domain reagents already in development or on the market, though claim-by-claim analysis against the specific rejected claims remains necessary.
Should you run an FTO against US16/282082 and its patent family?
Any organisation developing, manufacturing, or commercialising single-domain antibodies — particularly anti-IgG secondary reagents, detection kits, or nanobody-based diagnostic platforms — should assess the full patent family around US16/282082. Although the US application has been found unpatentable, granted counterparts in Europe or other jurisdictions may still pose infringement risk. The affirmed US unpatentability does not extinguish rights derived from foreign counterparts in the same priority family.
PatSnap Eureka’s FTO Search Agent can map the full international patent family of US16/282082, identify granted claims in active jurisdictions, and surface related single-domain antibody patents that may cover overlapping technical features. R&D and product teams can use Eureka to benchmark their own antibody engineering claims against the prior art cited in the USPTO rejection, reducing prosecution risk and informing commercialisation timelines for anti-IgG nanobody products.
Run a freedom-to-operate analysis on US20190177434A1 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit appeals: single-domain antibody and biologics patentability
Explore Federal Circuit appeals affirming USPTO unpatentability findings in the single-domain antibody, nanobody, and biologics patent prosecution space.
What this case signals for the single-domain antibody IP landscape
Federal Circuit affirmance of USPTO unpatentability shapes freedom-to-operate and prosecution strategy across the single-domain antibody sector.
Anti-IgG single-domain antibody claims face high prior art hurdles at USPTO
This outcome is consistent with USPTO and Federal Circuit scrutiny of broad single-domain antibody claims, particularly where the prior art field is dense. Companies prosecuting similar applications should anticipate §102/§103 rejections and build claim strategies around narrow, differentiated structural or functional features from the outset.
Thermo Fisher’s involvement signals commercial stakes beyond the named applicant
The appearance of Thermo Fisher Scientific as plaintiff law firm — rather than a specialist IP boutique — suggests this application had commercial significance within a larger product or licensing strategy. Parties monitoring competitive IP in the research antibody and detection reagent market should track related continuation filings by BAC IP B.V. and its affiliates.
B.V. v DERRICK — key questions answered
The Federal Circuit affirmed the USPTO’s finding that BAC IP B.V.’s application US16/282082 — covering single-domain antigen-binding proteins that bind mammalian IgG — was unpatentable. The court found no reversible error in the agency’s determination. The order was entered on 5 August 2025, closing the appeal after 378 days.
The patent application at issue is US16/282082, published as US20190177434A1. It covers single-domain antigen-binding proteins — a class of engineered antibody fragments (nanobodies/VHH domains) — designed to bind mammalian immunoglobulin G (IgG). These proteins are relevant to secondary antibody reagents used in immunoassay and diagnostic applications.
No. The Federal Circuit’s affirmance of unpatentability applies only to the US application US16/282082. Any counterpart applications filed at the EPO, in national European jurisdictions, or in Asia operate under separate legal systems and are not bound by this outcome. Companies seeking FTO comfort should conduct jurisdiction-specific searches for granted counterparts in the same priority family.
Potentially, if a continuation or continuation-in-part application with materially amended claims was filed before this decision and remains pending. The affirmance forecloses the specific claims at issue but does not bar new filings with differentiated claim scope. The USPTO application register should be monitored for related BAC IP B.V. or Thermo Fisher-linked filings in the same priority chain.
Thermo Fisher Scientific appears in the case record as the plaintiff law firm, which is atypical and suggests the company had a direct commercial interest in the underlying patent application — possibly as assignee, licensee, or through a corporate relationship with BAC IP B.V. This connection indicates the application had strategic relevance for Thermo Fisher’s research reagent or antibody product portfolio, making the outcome commercially significant beyond BAC IP B.V. alone.
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