Immunohistochemistry effectively reveals the heterogeneous nature of fibroblast growth factor receptor 2b (FGFR2b) expression and antigen accessibility across diverse tumor histologic types, a variability significantly influenced by tissue type and fixation quality, both of which profoundly impact target antigen accessibility within formalin-fixed, paraffin-embedded (FFPE) tissue specimens. Retrieval parameters on automated staining platforms can impact staining outcomes and assay sensitivity. A comprehensive optimization of staining procedures, encompassing antigen retrieval, proteolytic enzyme digestion, primary antibody incubation, and detection selections, yielded 2 distinct protocols designed for specific tumor types. The protocols were tailored to maximize performance on their respective tumor types, with one protocol optimized for gastric and gastroesophageal junction (G/GEJ) adenocarcinoma, and the other fine-tuned for non-small cell lung cancer (NSCLC) and a broader spectrum of solid tumors.To optimize an FGFR2b (FPR2-D) assay for NSCLC and a broader spectrum of solid tumors through modification of the established VENTANA FGFR2b (FPR2-D) Mouse Monoclonal Antibody assay, originally validated for G/GEJ adenocarcinoma.Multiple FGFR2b assay protocols were used to stain sections of FFPE tissue from commercially procured specimens spanning 10 tumor types. Each specimen was evaluated to select the preferred protocol parameters that achieved strong specific staining with minimal background. The assay was then assessed for sensitivity, specificity, and repeatability.The optimal gastric cancer tissue staining protocol for the VENTANA FGFR2b (FPR2-D) Mouse Monoclonal Antibody was referenced to develop an assay for other solid tumor types.This investigation shows the importance of parameter screening approaches when evaluating FGFR2b across tumor types in immunohistochemistry to ensure optimal staining performance.