Chemoimmunotherapy Combination for Solid Tumors

Novel cancer immunotherapies targeting the immunosuppressive PD-1/PD-L1 pathway result in durable clinical benefit in a subset of patients; however, primary or acquired resistance is common, affecting up to two-thirds of the patients in various tumor types. Therefore, a substantial effort is currently underway to fully elucidate the mechanisms of resistance to immune checkpoint blockade and to design more effective therapeutic strategies. Conventional anticancer treatments, including chemotherapy, radiation therapy, and targeted therapy, execute anticancer activity through direct cancer cell killing. Recent appreciations of the immune regulatory effects of these therapeutic agents have led to the exploration of their utilization in combination with immune checkpoint inhibitors, aiming to achieve synergetic effects and to improve the response and durability of immunotherapy. Here, we will provide an updated review of the immunomodulatory effects of cytotoxic chemotherapy and their impacts on reshaping modern cancer immunotherapy. The ongoing clinical trials of these combination therapies and their results will be briefly discussed here, since they will also be reviewed in other sections of this book. The combination of different immunotherapy agents, such as PD-1 antibody in combination with CTLA-4 antibody, is not a focus here; instead it is discussed in the overview and other disease-specific chapters.