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This content is intended for pathologists
FGFR2b protein overexpression can be defined as moderate 
(2+) to strong (3+) membranous staining of tumor cells1-3

  • Intensity
  • Controls
  • Non-specific

FGFR2b protein overexpression can be defined as moderate (2+) to strong (3+) staining1-3

(0) no staining FGFR2b protein overexpression evaluation by IHC | (1+) weak staining FGFR2b protein overexpression evaluation by IHC
(0) no staining FGFR2b protein overexpression evaluation by IHC | (1+) weak staining FGFR2b protein overexpression evaluation by IHC
(2+) moderate staining FGFR2b protein overexpression evaluation by IHC | (3+) strong staining FGFR2b protein overexpression evaluation by IHC
(2+) moderate staining FGFR2b protein overexpression evaluation by IHC | (3+) strong staining FGFR2b protein overexpression evaluation by IHC
Gastric/GEJ cancers can exhibit varying levels of FGFR2b membranous staining intensity ranging from no staining (0) to strong staining (3+)1

FGFR2b protein overexpression can exhibit mixed staining intensities4

EGE gastric adenocarcinoma, stained with H&E at 20x magnification
20x-h-e-mob
Image of a cell illustrating varying levels of partial membrane staining: weak (1+), moderate (2+), and strong (3+)Presence of weak (1+), moderate (2+), and strong (3+) partial membrane staining
20x-fgfr2b-mobPresence of weak (1+), moderate (2+), and strong (3+) partial membrane staining
10 fgfr2b gastric adenocarcinoma with partial membrane staining categorized as weak, moderate, and strongPresence of weak (1+), moderate (2+), and strong (3+) partial membrane staining
10x-fgfr2b-mobPresence of weak (1+), moderate (2+), and strong (3+) partial membrane staining

A recommended system-level control for FGFR2b IHC testing is non-neoplastic skin tissue5

An appropriate system-level control exhibits both weak and moderate membrane staining5

Detailed view of a skin cell with a high concentration of white blood cells, highlighted by H&E staining in non-neoplastic skinH&E of non-neoplastic skin
Image of immunohistochemistry results displaying weak to moderate staining of FGFR2b in basal epithelium of non-neoplastic skin.FGFR2b in non-neoplastic skin exhibiting weak (1+) to moderate (2+) membrane staining on basal epithelium
Immunohistochemistry image of non-neoplastic skin, showing IgG negative control with anti-c-jun antibody staining.lgG negative control of non-neoplastic skin

Scoring criteria for the VENTANA® FGFR2b (FPR2-D) Mouse Monoclonal Antibody for evaluation of non-neoplastic skin tissue as a system-level control5

Staining acceptability Staining pattern
Acceptable
  • Presence of weak and moderate membrane staining in the epithelium of skin; and
  • Absence of weak to moderate staining in dermis
Unacceptable
  • Absence of weak or moderate membrane staining in the epithelium of skin; or
  • Presence of cytoplasmic-only staining; or
  • Presence of any weak or moderate staining in skin dermis; or
  • Non-specific FGFR2b (FPR2-D) background staining that interferes with interpretation
Not evaluable

Interpretation is not possible, eg, no tissue/tumor present, artifacts, or edge artifacts

Non-specific staining can be detected in:

Plasma cells — Gastric Adenocarcinoma4

H&E Presence of plasma cellsPresence of plasma cells
Non specific plasma cell stainingNon-specific plasma cell staining
IgG negative control image showing non-specific neoplastic skin tissue under microscopic examinationNegative control

Chief cells — Gastric Adenocarcinoma4

Chief H&E cells adjacent to normal cellsAdjacent normal. Presence of Chief cells
Image of a cell labeled "fgfr2b" alongside normal non-specific staining of chief cellsAdjacent normal with non-specific Chief cell staining
Image of a cell line with adjacent normal non-specific chief cell staining and accompanying text descriptionAdjacent normal with non-specific Chief cell staining

Clot staining4

Image of gastric adenocarcinoma showing the presence of a clot in the affected tissueGastric adenocarcinoma — Presence of clot
A white sheet displaying the text "fgfr2b," related to gastric adenocarcinoma with non-specific clot stainingGastric adenocarcinoma with non-specific clot staining
IgG gastric adenocarcinoma with non-specific clot staining" in clear, bold textGastric adenocarcinoma with non-specific clot staining

DAB trapping4

cell image with non-specific DAB trap stainingNon-specific staining: DAB trap

DAB, 3,3'-diaminobenzidine tetrahydrochloride; FGFR2b, fibroblast growth factor receptor 2, isoform IIIb; GEJ, gastroesophageal junction; H&E, hematoxylin and eosin; IgG, immunoglobulin G; IHC, immunohistochemistry.

References: 1. Ahn S, et al. Mod Pathol. 2016;29:1095-1103. 2. Wainberg ZA, et al. Lancet Oncol. 2022;23:1430-1440. 3. Wainberg ZA, et al. Gastric Cancer. 2024;27:558-570. 4. Data on File, Amgen; 2024. 5. Roche Diagnostics. https://elabdoc-prod.roche.com/eLD/api/downloads/65a1283e-a4f6-ee11-2591-005056a71a5d?countryIsoCode=XG. Accessed May 15, 2025.

References: 1. FPO 2. FPO 3. FPO