Immune Checkpoint Inhibitors in Oncology

In this chapter, we explore the evolution and current state of immune checkpoint inhibitors (ICIs) in cancer treatment, focusing on their mechanism of action, FDA-approved agents, and novel immune checkpoints. Understanding ICIs is critical since ICIs have revolutionized the treatment for many solid tumors and some hematological malignancies after the first approvals in the early 2010s. First, we review concepts to help gain an understanding of immunotherapy in general, such as monoclonal antibodies and immune checkpoints. We then focus on the current ICI treatment landscape, including the use of ipilimumab, nivolumab, pembrolizumab, and relatlimab in the metastatic, adjuvant, and neoadjuvant settings. Additionally, we discuss new upcoming treatment targets. Finally, we review the side effects of ICI treatments, also known as immune-related adverse events (irAEs), and special circumstances where ICIs should be used with caution. At the end of the chapter, the reader will gain insight on general concepts in immunotherapy and obtain an understanding on the current standard of care regimens using ICIs.