Post-Progression Survival Influences Overall Survival among Patients with Advanced Non-Small Cell Lung Cancer Undergoing First-Line Pembrolizumab Monotherapy.

BACKGROUND Among patients with non-small cell lung cancer (NSCLC), the impact of first-line treatment on overall survival (OS) may be influenced by subsequent therapies. Thus, using patient-level data, we assessed the relationships of progression-free survival (PFS) and post-progression survival (PPS) with OS among patients with high-programmed death-ligand 1 (PD-L1) expression undergoing first-line pembrolizumab monotherapy for NSCLC. METHODS We reviewed data from 133 patients with high PD-L1 expression undergoing first-line pembrolizumab monotherapy for NSCLC at 6 Japanese centers between February 2017 and December 2018. The correlations of PFS and PPS with OS were evaluated at the patient level. RESULTS Linear regression analyses and Spearman's rank correlation coefficient revealed that PPS was strongly correlated with OS (r = 0.76, p < 0.05, R2 = 0.65), while PFS was only moderately correlated with OS (r = 0.71, p < 0.05, and R2 = 0.4). Furthermore, PPS was significantly associated with performance status at the end of pembrolizumab monotherapy, as well as the use of platinum-based combination chemotherapy after pembrolizumab monotherapy (both p < 0.05). CONCLUSIONS Among patients with high PD-L1 expression undergoing first-line pembrolizumab monotherapy for NSCLC, PPS was more strongly correlated with OS, relative to the relationship between PFS and OS. Therefore, subsequent treatment appears to significantly influence OS in patients with disease progression following first-line pembrolizumab monotherapy.