Efficacy of immune checkpoint inhibitors according to PD-L1 tumor proportion scores in non-small cell lung cancer.

Background We correlated the tumor proportion score (TPS) of programmed cell death ligand 1 (PD-L1, SP263 or 22C3) expression with the disease control rate (DCR, partial remission and stable disease), and progression free survival (PFS) after nivolumab or pembrolizumab treatment. Methods A total of 70 case records (55 males, 15 females) of patients with non-small cell lung cancer (NSCLC, 46 adenocarcinoma, 22 squamous cell carcinoma, and two others) were reviewed. The PD-L1 expressions were divided into High (SP263 >= 30%, 22C3 >= 80%) and Low groups (SP263 < 30%, 22C3 < 80%). In the combined analysis, the PD-L1 group was defined as High if either of the two stains was classified as High and defined as Low if both stains were classified as Low. Results Among the patients treated with nivolumab (n = 37), the SP263 High group showed higher DCR compared to the SP263 Low group (52.6% vs. 11.1%, P = 0.024). In patients treated with pembrolizumab (n = 33), no significant difference in DCR and PFS according to PD-L1 expression was observed. In the combined analysis (n = 36), patients in the PD-L1 High group showed significantly higher DCRs than those in the PD-L1 Low group (56.1% vs. 24.1%, P = 0.028). PFS was significantly longer in the PD-L1 High group than in the Low group (medians 4.1 vs. 1.6 months, respectively, P = 0.04). Conclusion A high expression level of PD-L1 was correlated with a significantly higher DCR and longer PFS in NSCLC patients treated with nivolumab or pembrolizumab.