Association of Immune-Related Adverse Effects and Survival in Solid Tumor Patients Treated with PD1 Inhibitors

Background The development of immune-related adverse effects (irAEs) can corroborate with the response to immune checkpoint inhibitors (ICIs), including programmed cell death 1 (PD1) inhibitors. However, there is extremely limited data on the association of irAEs with survival in patients who have shown a response to ICIs. Patients and Methods This study is a retrospective audit of the prospectively collected database of patients who received PD1 inhibitors for advanced solid tumors. Responders were defined as patients who attained the best response of either complete response or partial response. Time-to-event analysis was done using the Kaplan–Meier estimator, and the hazard ratio (HR) was calculated by using Cox proportional model. A point-biserial correlation was used to find out the potential influence of irAEs on overall survival (OS). Results A total of 155 patients (49% lung cancer, 31% head and neck cancer) who received ICI during the specified period were evaluated for this study. The overall response rate was 19.4% and disease control rate was 43.2%. The median (OS) for patients who developed irAE was 12.3 months (95% confidence interval [CI]: 8.9–15.6), while it was not reached for patients without irAE (HR: 10.5, 95% CI: 1.2–NR, p = 0.007). One-year OS for the corresponding group of patients was 53.6% (standard deviation [SD]: 15.6) versus 92.9% (SD: 6.9), respectively. Among responders, 12 (40%) developed at least grade 1 irAE, while among nonresponders, 38 (30.4%) developed irAE ( p = 0.312). Conclusions In our study, we found significant improvement in survival of solid tumor patients treated with ICIs who developed irAEs on treatment as compared with those who did not. On specifically analyzing patients who responded to ICIs, there was no difference in OS who developed irAEs versus those who did not. However, this needs to be studied in a larger sample to reach a definite conclusion.