CAR-T cell therapy for cancer: current challenges and future directions

Chimeric antigen receptor T (CAR-T) cell therapies have transformed the treatment of relapsed/refractory (R/R) B-cell malignancies and multiple myeloma by redirecting activated T cells to CD19- or BCMA-expressing tumor cells. However, this approach has yet to be approved for acute myeloid leukemia (AML), the most common acute leukemia in adults and the elderly. Simultaneously, CAR-T cell therapies continue to face significant challenges in the treatment of solid tumors. The primary challenge in developing CAR-T cell therapies for AML is the absence of an ideal target antigen that is both effective and safe, as AML cells share most surface antigens with healthy hematopoietic stem and progenitor cells (HSPCs). Simultaneously targeting antigen expression on both AML cells and HSPCs may result in life-threatening on-target/off-tumor toxicities such as prolonged myeloablation. In addition, the immunosuppressive nature of the AML tumor microenvironment has a detrimental effect on the immune response. This review begins with a comprehensive overview of CAR-T cell therapy for cancer, covering the structure of CAR-T cells and the history of their clinical application. It then explores the current landscape of CAR-T cell therapy in both hematologic malignancies and solid tumors. Finally, the review delves into the specific challenges of applying CAR-T cell therapy to AML, highlights ongoing global clinical trials, and outlines potential future directions for developing effective CAR-T cell-based treatments for relapsed/refractory AML.