The field of immuno-oncology continues to rapidly evolve as new insights to fight and treat cancer emerge. The fourth edition of Immunotherapy provides the most current overview of immuno-oncology in different cancer types and toxicities associated with immunotherapy. While immunotherapy has revolutionized the treatment landscape of several solid malignancies, several challenges still exist. Only a subset of patients derive clinical benefits; some do not respond at all, and others respond initially, only for their disease to progress later. Because these drugs can activate a broad range of immune cells, patients suffer from a unique set of side effects known as immune-related adverse events. As more immunotherapeutic agents are used in the clinic, it is important to provide updates about current and ongoing developments in the field to further research efforts and inform treatment decisions. The fourth edition will have a new focus on strategies to overcome the challenges associated with immunotherapy. Chapters will discuss topics such as biomarkers of response, resistance mechanisms, role of imaging in predicting immune-related adverse events, and management of immune-related adverse events. Written by leading experts conducting cutting-edge research, readers will gain up-to-date knowledge on the current state and future of immunotherapy.