CAR Beyond αβ T Cells: Unleashing NK Cells, Macrophages, and γδ T Lymphocytes Against Solid Tumors

Chimeric antigen receptor (CAR)-engineered cell therapy represents a landmark advancement in cancer immunotherapy. While αβ CAR-T therapy has demonstrated remarkable success in hematological malignancies, its efficacy in solid tumors remains constrained mainly by factors such as antigen heterogeneity, immunosuppressive microenvironments, and on-target/off-tumor toxicity. To overcome these limitations, emerging CAR platforms that utilize alternative immune effectors, including natural killer (NK) cells, macrophages, and γδ T lymphocytes, are rapidly gaining traction. This review systematically analyzes the mechanistic advantages of CAR-NK, CAR-M, and CAR-γδ T cell therapies, while critically evaluating persistent challenges in clinical translation, including limited cell persistence, manufacturing scalability, and dynamic immune evasion mechanisms. We further discuss innovative strategies to enhance therapeutic efficacy through some viable strategies. By bridging fundamental immunology with translational engineering, this work provides a roadmap for developing CAR therapies capable of addressing the complexities of solid tumor eradication.