In addition to chimeric antigen receptor (CAR)-alpha beta T-cell therapy, CAR-NK, CAR-NKT, CAR-M and CAR-gamma delta T-cell therapy have gradually been applied to the treatment of solid tumors. Compared to hematological tumors, solid tumors have the characteristics of strong tumor heterogeneity, limited target antigen selection, and low T-cell infiltration to build immunosuppressive tumor microenvironment. These features would present great obstacles to CAR cell therapy. This paper comprehensively analyzed the application of different CAR cells to solid tumors and summarized the design principles of different CAR cells to provide the direction for the development of CAR cell therapy in solid tumors.
