[OBJECTIVES] This study aimed to evaluate the safety and efficacy of nivolumab and pembrolizumab in elderly patients in outpatient settings.

[METHODS] The safety and efficacy of nivolumab and pembrolizumab were compared retrospectively among patients at the Veterans Health Service (VHS) Medical Center in Seoul, South Korea, from September 1, 2017 to August 25, 2018.

[RESULTS] Eighty-seven patients were selected for the study. The median progression-free survival was 63 days for nivolumab (95% confidence interval (CI), [14 to 282]) vs. 243 days for pembrolizumab (95% CI, [22 to 348]) (p =0.04). The objective response rate (ORR) was 0% in the nivolumab group vs 5.6% in the pembrolizumab group (p =0.310). All the patients exhibited treatmentrelated adverse effects. More than 89% of the patients exhibited diseases of the gastrointestinal (GI) tract. Pneumonia, of grades three or higher, was the most common adverse effect, followed by weakness and anorexia.

[CONCLUSIONS] There was no statistically significant difference between the nivolumab group and the pembrolizumab group with respect to the ORR. The incidence and severity of the adverse effects in this study were higher than those of previous studies; however, these adverse effects are generally manageable in a real-world clinical setting. Further randomized controlled studies will be necessary to confirm these results in elderly patients.