Objective: The advent of immunotherapy has significantly changed the treatment and management of patients with advanced non-small cell lung cancer (NSCLC). Prior to initiation of immunotherapy, evaluation of programmed death ligand 1 (PD-L1) expression is required. One factor that affects PD-L1 expression in NSCLC is the presence of oncogenic driver mutations; however, little data on its association is available, especially in the Philippine setting. The study aims to determine the prevalence of PD-L1 expression and its association with driver mutations among patients with non-small cell lung cancer in a private tertiary care hospital in the Philippines. Methodology: The study was undertaken for a period of two years from July 2017-July 2019 at St. Luke’s Medical Center and included 446 NSCLC samples. PD-L1 was evaluated by immunohistochemistry using 22C3 anti-PD-L1 antibody clone, EnVision FLEX visualization system on Autostainer Link 48. Patient demographics and data on driver mutation testing were recorded. Statistical analysis was performed using logistic regression. Results: PD-L1 expression was observed in 273 (61.20%) of 446 cases, 119 (61.20%) of which demonstrated high PD-L1 expression while 154 (34.50%) had low PD-L1 expression. There was no significant association between PD-L1 expression and EGFR mutation, ALK mutation, age, and gender. For histologic type, high PD-L1 expression was significantly associated with adenocarcinoma and non- small cell carcinoma, NOS. Conclusion The overall prevalence of PD-L1 expression in non-small cell lung carcinoma is 61.20% based on the cases included. Although we did not find an association between PD-L1 expression and EGFR and ALK mutation, our study observed that ALK-mutated NSCLCs have 4.7 odds of having high PD-L1 expression, however, a higher sample size is warranted to truly determine significant association. The outcome of this study may provide help in the stratification of patients and predict those who will benefit from immunotherapy.
Carcinoma, Non-Small-Cell Lung ; B7-H1 Antigen