Clinical impact of pembrolizumab combined with chemotherapy in elderly patients with advanced non-small-cell lung cancer

Objectives Combination therapy of immune checkpoint inhibitors and chemotherapy is considered to be one of the standard treatment options for patients with advanced non-small-cell lung cancer (NSCLC). However, the clinical significance of immune checkpoint inhibitors combined with chemotherapy in elderly patients with NSCLC has not yet been fully understood. Therefore, this study aimed to evaluate how aging affects the therapeutic impact of chemotherapy combine with immune checkpoint inhibitors in elderly patients. Materials and methods We retrospectively analyzed 203 patients with advanced NSCLC who were treated with the combination therapy of pembrolizumab and chemotherapy between January 2019 and December 2019 at 12 institutions in Japan. We analyzed the clinical impacts of age on the following two groups: those who received pembrolizumab with platinum and pemetrexed (pemetrexed regimen) and those who received pembrolizumab with carboplatin and nab-paclitaxel/paclitaxel (paclitaxel regimen). Progression-free and overall survival were assessed via the Kaplan-Meier method. Results Multivariate analysis demonstrated that progression-free and overall survival were significantly shorter in elderly patients (aged ≥75 years) with NSCLC than in non-elderly patients (aged <75 years) with NSCLC in the pemetrexed regimen group. In contrast, there were no significant differences in progression-free and overall survival between elderly patients and non-elderly patients with NSCLC in the paclitaxel regimen group. In elderly patients with NSCLC, a programmed death-ligand 1 tumor proportion score of ≥50% was significantly associated with progression-free survival, and performance status of ≥2 was significantly associated with overall survival. Low albumin level (<3.5 g/dL) was significantly associated with both progression-free and overall survival. Conclusion The results of this retrospective study show that the pemetrexed regimen, but not the paclitaxel regimen, was related to poor clinical outcomes in elderly patients with NSCLC.