Correlation of Immune-Related Adverse Events and Effects of Pembrolizumab Monotherapy in Patients with Non-Small Cell Lung Cancer

PURPOSE: The effects of immune checkpoint inhibitors have been reported to be linked with immune-related adverse events (irAEs). In patients with advanced non-small-cell lung cancer, who tested positive for programmed death-ligand 1 (PD-L1), pembrolizumab, an immune checkpoint inhibitor can be used as a treatment, and it was found to improve overall survival. However, there are only a few reports on the relationship between the therapeutic effects of pembrolizumab in patients with lung cancer and the irAEs of pembrolizumab. The purpose of this study was to determine the correlation between immune-related adverse events and the effects of pembrolizumab monotherapy in patients with non-small-cell lung cancer. PATIENTS AND METHODS: From February 2017 to August 2019, we conducted a retrospective analysis of the effects of pembrolizumab treatment and immune-related adverse events in 94 patients with non-small-cell lung cancer treated with pembrolizumab only. RESULTS: In 63 cases, irAEs were observed. The most common irAE was rash. PD-L1 positivity ≥ 50% tended to cause irAEs. The median progression-free survival (PFS) rates with and without irAEs were 371 days (95% CI, 184-NR) and 67 days (95% CI, 51–87 days), respectively. In a multivariate analysis, irAEs and Eastern Cooperative Oncology Group performance status (PS) were the factors related to PFS. CONCLUSION: In patients with lung cancer, who were treated with pembrolizumab monotherapy, the development of irAEs was likely indicative of the positive effects of pembrolizumab. This novel finding appears to be useful for clinicians who work with pembrolizumab for lung cancer treatment.