Comparison of time to failure of pembrolizumab plus chemotherapy versus pembrolizumab monotherapy: a consecutive analysis of patients having NSCLC with high PD-L1 expression.

INTRODUCTION: There are two treatment strategies for non-small cell lung cancer (NSCLC) exhibiting a high expression level of programmed death-ligand 1 (tumor proportion score ≥ 50%): pembrolizumab plus chemotherapy and monotherapy. We retrospectively compared their efficacy and safety. MATERIALS AND METHODS: We reviewed the efficacy and safety of first-line pembrolizumab-containing regimens administered between 2017 and 2020 to consecutive patients. The patients were divided into a pembrolizumab plus chemotherapy group (Combo group) or monotherapy group (Mono group). To compare the efficacy, we monitored the time to failure of strategy (TFS) defined as the time from the start of treatment to the occurrence of one of the following events: the addition of any drug not included in the primary strategy, progression of cancer after complete therapy, progression and no subsequent therapy, or death, whichever occurred first. We used the propensity score matching (PSM) to reduce the bias. RESULTS: A total of 126 patients were identified (89 in the Mono group and 37 in the Combo group). PSM matched 36 individuals from each of the two groups. The overall response rate and median progression-free survival of the Combo group were better than those of the Mono group. However, the median TFS was almost the same (11.3 months vs. 14.9 months; hazard ratio 1.40 [95% confidence interval 0.62-3.15]). The frequency of all serious adverse effects was higher in the Combo group than in the Mono group. DISCUSSION: Due to similar efficacy in TFS, both pembrolizumab plus chemotherapy and monotherapy are valid options for NSCLC.