Prognostic Significance of the Severity of Immune-Related Adverse Events in Advanced Cancer Patients Treated with PD-1/PD-L1 Inhibitors: A Real-World Data Analysis

Background There is limited evidence regarding immune-related adverse events (irAEs) in Asian cancer patients treated with antibodies directed against programmed cell death-1 (PD-1) or programmed cell death-ligand 1 (PD-L1). Objective This study aimed to investigate the clinical patterns and prognostic significance of grade 1–2 and grade ≥ 3 irAEs by PD-1/PD-L1 inhibitors in cancer patients using real-world clinical data. Patients and Methods We conducted a retrospective study of cancer patients who received pembrolizumab, nivolumab, or atezolizumab at a tertiary hospital in South Korea. Incidence, time to onset, and grade 1–2 and grade ≥ 3 irAE risk factors were analyzed from medical records. The association of irAE severity with progression-free survival (PFS) and prognostic factors for PFS were evaluated. Results Among a total of 431 patients, irAEs occurred in 45.2%, and 9.5% were grade ≥ 3 irAEs. There were no significant differences in the median time to onset based on severity. Risk factors for the development of grade ≥ 3 irAEs were the presence of autoimmune disorders or diabetes mellitus. The median PFS was significantly different at 13.20, 9.00 and 4.17 months for the grade 1–2, grade ≥ 3, and no irAE groups, respectively. An increase in administration cycles was associated with a reduced risk of progression in patients with grade 1–2 and grade ≥ 3 irAEs. Conclusions The development of grade ≥ 3 irAEs was affected by comorbidities and associated with improved PFS compared with those without irAEs. Our findings identified the real-world epidemiology, risk factors, and prognostic significance of irAEs, which may guide treatment decisions of PD-1/PD-L1 inhibitors.