Immuno-oncology (IO) is one of the fastest growing therapeutic areas within oncology. IO agents work indirectly via the host's adaptive and innate immune system to recognize and eradicate tumor cells. Despite checkpoint inhibitors being only introduced to the market since 2011, they have become the second most approved product category. Current Food and Drug Administration (FDA)-approved classes of IO agents include: immune checkpoint inhibitors (ICIs), chimeric antigen receptor T-cell therapy (CAR-T), bi-specific T-cell engager (BiTE) antibody therapy, T-cell receptor (TCR) engineered T cell therapy, tumor-infiltrating lymphocyte (TIL) therapy, cytokine therapy, cancer vaccine therapy, and oncolytic virus therapy. Cancer immunotherapy has made progress in multiple cancer types including melanoma, non-small cell lung cancer (NSCLC), renal cell carcinoma (RCC), and urothelial carcinoma
however, several cancers remain refractory to immunotherapy. Future directions of IO include exploration in the neoadjuvant/perioperative setting, combination strategies, and optimizing patient selection through improved biomarkers.