Prognostic significance of PD-L1 in patients with non-small cell lung cancer: A large cohort study of surgically resected cases

Introduction: The aim of our analysis was to evaluate the prognostic effect of programmed cell death ligand-1 (PDL1) expression in patients with non-small cell lung cancer (NSCLC). Methods: PD-L1 expression among 1070 surgically resected NSCLC specimens was evaluated by immunohistochemical analysis. Data were analyzed using Cox proportional hazard models adjusting for age, sex, smoking status, histologic type, stage, and performance status. Results: Sixty-eight patients (6%) were strongly PD-L1 positive and 410 (38%) were weakly PD-L1 positive. A significantly higher prevalence of PD-L1 positivity was observed among patients with squamous cell carcinoma and among stage IIIB and IV patients. PD-L1 expression may be associated with poorer overall survival, with an adjusted hazard ratio of 1.56 (95% confidence interval [CI]: 1.08- 2.26, p = 0.02) for strong PD-L1 positivity, 1.18 (95% CI: 0.96-1.46; p = 0.12) for weak PD-L1 positivity, and 1.23 (95% CI: 1.00-1.51; p = 0.05) for the combined strongly and weakly positive groups compared with PD-L1 negativity. Negative prognostic effect of PD-L1 expression was not statistically significant after adjustment for postoperative chemotherapy or radiotherapy. Similar results were observed for progression-free survival. Among stage I patients, the disease recurrence rate was higher in the PDL1- positive versus in the PD-L1-negative group (48% versus 27%, p < 0.001), with an adjusted hazard ratio for disease-free survival of 2.01 (95% CI, 1.08-3.73; p = 0.03) for strong PD-L1 positivity and 1.57 (95% CI, 1.17-2.11; p = 0.003) for weak PD-L1 positivity compared with PD-L1 negativity. Conclusions: Tumor PD-L1 expression may be associated with poor prognosis in patients with NSCLC, although its significance weakens when postoperative therapy is considered.