Cladribine‐ and decitabine‐containing conditioning regimen has a low post‐transplant relapse rate in patients with relapsed or refractory acute myeloid leukemia and high‐risk myelodysplastic syndrome

To reduce the risk of relapse after allogeneic hematopoietic stem cell transplantation (allo‐HSCT), there have been continuing efforts to optimize the conditioning regimens. Our study aimed to analyze the risk factors associated with the relapse of relapsed/refractory (R/R), high‐risk acute myeloid leukemia (AML) and high‐risk myelodysplastic syndrome (MDS) post‐transplant and the efficacy of a new conditioning regimen involving decitabine and cladribine. Clinical data of 125 patients with R/R AML, high‐risk AML and high‐risk MDS who underwent allo‐HSCT were collected. In addition, 35 patients with R/R AML, high‐risk AML and high‐risk MDS received treatment with a new conditioning regimen including decitabine and cladribine. Cox regression analysis was used to identify risk factors associated with OS, RFS and relapse. Among 125 patients who underwent allo‐HSCT, CR before allo‐HSCT and matched sibling donors were independent protective factors for OS. DNMT3A abnormality was an independent risk factor for both relapse and RFS. Among 35 patients who received a new conditioning regimen containing decitabine and cladribine, only six patients relapsed and 1‐year cumulative incidence of relapse was 11.7%. Moreover, this new regimen showed efficient MRD clearance early after allo‐HSCT. The combined decitabine‐ and cladribine‐based conditioning regimen showed a low relapse rate and a high survival without an increased incidence of GVHD or adverse effects and thus has potential for use in allo‐HSCT for R/R AML, high‐risk AML and high‐risk MDS. What's new? Despite the success of allogeneic hemopoietic stem cell transplantation (allo‐HSCT) for advanced myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), some 30% to 40% of patients experience disease relapse. Moreover, while conditioning regimens can reduce relapse rates, outcomes remain poor. Here, investigation of relapsed/refractory, high‐risk AML and MDS patients who underwent allo‐HSCT reveals independent associations between better survival and complete remission before allo‐HSCT and matched sibling donors. In addition, a decitabine‐ and cladribine‐based conditioning regimen was associated with a low relapse rate and high survival, without adverse effects, revealing potential value for use in relapsed/refractory, high‐risk AML and MDS patients.