CAR-T treatment of acute leukemia in adults

The prognosis for acute lymphoblastic leukemia (ALL) in adults remains poor in refractory or relapsed (R/R) situations. Among the immunotherapy strategies that have recently been developed, CAR-T cells (chimeric antigen receptor modified T-cells) represent a major technological and therapeutic advance in the management of adult and pediatric patients with such resistant diseases. The first CAR-T trials targeting the ubiquitous B-cell antigen CD19 showed very encouraging results with complete remission rates of approximately 80%. Cytokine release syndrome (CRS) and neurotoxicity are two major and potentially life-threatening adverse events, that require coordinated management with intensive care units and graduated use of IL-6 pathway blocking antibodies and steroids. In addition to immediate toxicity, many clinical issues arise such as ALL treatment from apheresis to CAR-T infusion, the role of allogeneic hematopoietic stem cell transplant (HSCT) before or after CAR-T therapy, or the reduction of escape mechanisms mostly driven by the loss of target expression. The development of these strategies in other subtypes of acute leukemias, including myeloid acute leukemia, is confronted with the expression of antigenic targets by healthy tissues and the potential risk of prolonged cytopenias. This review adopts a clinical perspective to detail the main results of CD19 CAR-T in ALL and the challenges raised by this new therapeutic approach.