Background and importance Pembrolizumab in monotherapy (in patients with PD-L1 expression ≥50%) or in combination with platinum-based chemotherapy (CT) (PDL-1 <50%) is the new standard therapy in first-line treatment of advanced or metastatic non-small cell lung cancer (mNSCLC).

Aim and objectives The aim of this study was to determine whether the incidence of immune-related adverse events (irAEs) following the use of pembrolizumab in first-line mNSCLC is associated with clinical outcomes in real-world practice.

Material and methods An observational, retrospective study was carried out, including patients with mNSCLC treated with pembrolizumab in first-line, between 1 January 2017 and 1 January 2021. Baseline patient characteristics were collected. To assess treatment effectiveness, the overall survival (OS) and progression-free survival (PFS) were measured. irAEs were categorised. OS and PFS were calculated for the population with any irAEs of any grade (irAEs+) and compared to patients without irAEs (irAEs–) in order to test our hypothesis.

Results The study included 62 patients with the following characteristics: mean age 67.44 years, majority of men (77.42%), smoking history (47% former smokers, 45% smokers), adenocarcinoma (87%), ECOG/PS-1=50%, ECOG/PS-0=38% and ALK/ROS-1/EGFR negative (89%), PD-L1 ≥50% (N=31), PDL-1 <50% (N=27) and unknown (N=4). Half of the patients received pembrolizumab alone and half received pembrolizumab in combination with CT. Most patients discontinued treatment due to progression (75.81%). irEAs (N=164) were observed in 77.4% of patients. In Kaplan–Meier analysis, median OS for overall, irAEs+ (N=48) and irAE– population (N=14) were as follows: 10.6 (95% CI 8.2 to 13.05), 10.9 (95% CI 8.6 to 13.2) and 4.4 months (95% CI 0 to 15.3), respectively. Median PFS for overall, irAEs+ and irAE– population were: 7.4 (95% CI 4.6 to 10,3), 8.7 (95% CI 5.9 to 11.6) and 2.3 months (95% CI 0 to 11.7), respectively. There were no significant differences in PFS and OS among the different populations.

Conclusion and relevance Our population did not reach statistical significance in the association between the presence of irEAs and clinical benefit. This may be due to the limited sample size.

References and/or acknowledgements 1. Hussaini S, et al. Association between immunerelated side effects and efficacy and benefit of immune checkpoint inhibitors – a systematic review and meta-analysis. Cancer Treat Rev 2021;92:102134. doi:10.1016/j.ctrv.2020.102134.

Conflict of interest No conflict of interest