(UroToday.com) Immune checkpoint inhibition has greatly improved clinical outcomes for patients with metastatic urothelial carcinoma and other cancers. Immune checkpoint inhibitors are associated with a class of adverse events, deemed immune-related adverse events due to immune activation. Nonetheless, biomarkers associated with immune-related adverse events are still lacking. Furthermore, high tumor mutational burden has been associated with better responses to immune checkpoint inhibitors in patients with metastatic urothelial carcinoma. At the 2021 GU ASCO annual meeting, Dr. Elie Akl presented the results of their study assessing the association of tumor mutational burden and immune-related adverse events. The authors hypothesized that the immune response against neoantigens is partly responsible for immune-related adverse events and investigated the association between immune-related adverse events, tumor mutational burden, and response to immune checkpoint inhibitors.