Prospects of Synergy: Local Interventions and CAR T Cell Therapy in Solid Tumors.

Chimeric antigen receptor T cell therapy has been established in the treatment of various B cell malignancies. However, translating this therapeutic effect to treat solid tumors has been challenging because of their inter-tumoral as well as intratumoral heterogeneity and immunosuppressive microenvironment. Local interventions, such as surgery, radiotherapy, local ablation, and locoregional drug delivery, can enhance chimeric antigen receptor T cell therapy in solid tumors by improving tumor infiltration and reducing systemic toxicities. Additionally, ablation and radiotherapy have proven to (re-)activate systemic immune responses via abscopal effects and reprogram the tumor microenvironment on a physical, cellular, and chemical level. This review highlights the potential synergy of the combined approaches to overcome barriers of chimeric antigen receptor T cell therapy and summarizes recent studies that may pave the way for new treatment regimens.