Evaluating outcomes after salvage therapy using chemotherapy or allogeneic stem cell transplantation for unresponsive acute myeloid leukemia

This study aimed to investigate the impact of salvage treatment using either chemotherapy (CT) or allogeneic hematopoietic stem cell transplant (allo-HSCT) on the overall outcome in patients with refractory (unresponsive) acute myeloid leukemia (AML). 

This study concluded that allo-HSCT benefits these patients and that direct transplant without salvage CT could be a treatment option. 

The overall outcome of patients with refractory AML (rAML) remains poor. For patients with rAML, salvage therapy is usually CT, followed by allo-HSCT. Salvage therapy is a treatment given after initial treatment does not work. However, allo-HSCT has been considered the only curative therapy for these patients. Therefore, it is important to evaluate whether allo-HSCT alone would benefit patients with rAML compared to salvage CT.  

This study involved data from 220 patients with rAML. 29 patients received allo-HSCT directly without salvage CT (group 1). 191 patients received salvage CT (group 2). Patients were followed up for an average of 24.4 months. 

In group 1, 89.7% achieved complete remission (CR) or complete remission with incomplete hematological recovery (CRi) after transplantation. The 4-year survival rate without relapse of AML was 45% in patients in group 1. The 4-year overall survival (OS) rate was 51.5% in group 1.  

In group 2, 42.4% of these patients achieved CR or CRi. 34 patients underwent allo-HSCT following salvage CT with 4-year survival rate without leukemia of 46% and 4-year OS of 46.2%.  

In patients in group 2 that failed to obtain CR or CRi but received rescue allo-HSCT with active disease, the 4-year survival rate without leukemia was 32.9% and 4-year OS was 36.9%. In patients who failed to respond to salvage CT and did not receive allo-HSCT, the 4-year survival rate without leukemia was 1.8% and the 4-year OS rate was 3.6%.

This study concluded that allo-HSCT is beneficial to patients with rAML and that direct allo-HSCT without salvage chemotherapy could be a treatment option for these patients. 

This study was based on medical records. The allo-HSCT group was significantly smaller than the salvage CT group. The CT patients received was different among patients. This might have influenced the results. Further large prospective studies are needed to confirm these results.