Advances in Allogeneic Hematopoietic Stem Cell Transplantation for Acute Leukemia

In acute leukemia, advances have been made in therapeutic strategies centered on allogeneic hematopoietic stem cell transplantation (allo-SCT), three of which are presented here. The indication of allo-SCT for acute myeloid leukemia (AML) in 1^st complete remission (CR1) has been debated. Genomic medicine has helped us gain a deeper understanding of this disease, some of which may serve as prognostic factors. Such genetic abnormalities could also help measure minimal residual disease (MRD) and provide additional clues to estimate the efficacy of chemotherapy. Combined with existing prognostic factors, these data can be used to construct a more accurate prognostic model, providing an optimal indication of allo-SCT for AML in CR1. Furthermore, overall treatment algorithms for high-risk AML after allo-SCT should include prophylactic and pre-emptive treatment to prevent relapse. These include immunotherapy using donor lymphocyte infusion (DLI), FLT3 inhibitors in FLT3-mutated AML, hypomethylating agents, or a combination of DLI with these agents. Clinical trials are currently ongoing to elucidate the role of these strategies, which will lead to a risk-adapted treatment for preventing relapse in high-risk AML. CD19-targeted chimeric antigen receptor (CAR) T-cell therapy induces a remarkable response in B-acute lymphoid leukemia (B-ALL); however, relapse remains a major problem. In this regard, allo-SCT as a consolidation treatment after CAR-T cell therapy for B-ALL is recommended for pediatric and adult patients. Achieving complete remission (CR) with CAR-T cell therapy is considered a promising bridging therapy to allo-SCT. Novel CAR-T treatment techniques are being developed to change their role as a pre-transplant treatment.