Immunohistochemical Evaluation of MET

MET immunohistochemical staining (MET-IHC) was evaluated using a Benchmark Ultra Autostainer (Ventana, Tucson, AZ) with anti-total c-MET (SP44) rabbit monoclonal primary antibody (Ventana, Tucson, AZ), following the manufacturer’s instructions. Staining was scored by determining the percentage of cells showing weak (1+), moderate (2+), or strong (3+) membranous staining. MET overexpression was considered as positive if ≥ 50% of tumor cells showing cellular membrane staining at an intensity of “2+” or “3+” [37 (link)]. Scoring was performed independently by two individuals and any discrepant cases were re-evaluated for the final interpretation.