Current state and future prospects of CAR T-cell therapy for myeloid malignancies

Abstract

Chimeric antigen receptor (CAR)-T cell therapy is among the most promising immunotherapies for hematological malignancies and can be used to treat myeloid malignancies in practice. However, developing CAR-T therapies for such diseases is particularly challenging due to the heterogeneity of target antigen expression across leukemic cells and patients, the difficulty in excluding on-target/off-target tumor effects, and the immunosuppressive tumor microenvironment. To date, various targets, including CD33, NKG2D, CD123, CLL-1, and CD7, have been actively studied for CAR-T cells, especially for acute myeloid leukemia (AML). Although no CAR-T cell products have been approved, several clinical trials have shown promising results, particularly for those targeting CLL-1 and CD123. Furthermore, new ideal targets and use of allogeneic or off-the-shelf CAR-T cell products are under investigation. Meanwhile, it remains unknown whether CAR-T therapy would be effective for other myeloid malignancies, including myelodysplastic syndromes and myeloproliferative diseases. This review discusses challenges in the development of CAR-T therapy for myeloid malignancies, especially for AML, from the perspectives of target antigen characteristics and disease-specific on-target/off-tumor toxicity. Moreover, it discusses the clinical development and prospects of CAR-T cells for these diseases.