FGFR2b protein expression by IHC (membranous staining)
Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.
| ID | BIO-FGFR2B-IHC |
|---|---|
| Type | Biomarker |
| Aliases | Bemarituzumab companion biomarkerFGFR2 IIIb isoformFGFR2b membrane IHCFGFR2b overexpressionFGFR2b protein expression (IHC)Експресія білка FGFR2b за ІГХ (мембранне забарвлення) |
| Status | reviewed 2026-05-07 | pending_clinical_signoff |
| Diseases | None declared |
| Sources | SRC-ESMO-GASTRIC-2024 SRC-FORTITUDE-101 SRC-NCCN-GASTRIC-2025 |
Biomarker Facts
| Biomarker type | protein_expression_ihc |
|---|---|
| Measurement | MethodIHC with FGFR2b-specific monoclonal antibody (FPR2-D, central laboratory assay used in FIGHT phase 2 and FORTITUDE-101 phase 3). Score: percentage of tumor cells with moderate-to-strong (2+/3+) membranous staining. Requires FGFR2b-IIIb-isoform-selective antibody — generic FGFR2 IHC does not distinguish isoforms. Unitscategorical: positive (FGFR2b 2+/3+ membranous staining in ≥10% of tumor cells, FORTITUDE-101 threshold) | negative |
| Related biomarkers | BIO-FGFR2 BIO-HER2-SOLID BIO-MSI-STATUS BIO-CLDN18-2 |
Notes
Distinct from BIO-FGFR2 (gene-level alterations: fusion / amplification / mutation). FGFR2b-IHC is the protein-level companion biomarker for bemarituzumab — anti-FGFR2b chimeric IgG1 mAb with afucosylated Fc enhancing ADCC. FIGHT phase 2 (Wainberg, Lancet Oncol 2022) used FGFR2b 2+/3+ in ≥10% of tumor cells as eligibility threshold; phase 3 FORTITUDE-101 (cite as-is — source stub pending citation upgrade) uses the same threshold. Companion-diagnostic IVD development ongoing alongside FORTITUDE-101 readout. Note: FGFR2-pan IHC and FGFR2b-IHC are NOT interchangeable — only the IIIb-isoform-selective antibody enables bemarituzumab patient selection.
Used By
Actionability
BMA-FGFR2B-MEMBRANE-GASTRIC- FGFR2b protein overexpression (IHC 2+/3+ membranous in ≥10% of tumor cells) identifies a...
Indications
IND-GASTRIC-METASTATIC-1L-FGFR2B-BEMARITUZUMAB- IND-GASTRIC-METASTATIC-1L-FGFR2B-BEMARITUZUMAB