Stem Cells Micro-transplantation in Elderly Patients Aged Over 70 With Acute Myeloid Leukemia: a Multicenter, Prospective, Non-interventional Study

BackgroundThe treatment outcomes of elderly patients aged over 70 with acute myeloid leukemia (AML) have been very disappointing. In comparison, our designed HLA-mismatched hematopoietic stem cell micro-transplantation (MST) has achieved such encouraging treatment results in AML patients as might warrant further investigations of the outcomes of MST for the above mentioned patients. MethodsOne hundred and eleven patients aged 70-88 years were enrolled. Eighty patients were assigned to the high-risk MST or standard MST group according to high-risk prognostic factors. The other thirty-one patients were assigned to either the chemotherapy group or support group. After receiving induction chemotherapy with cytarabine and anthracycline, patients who achieved complete remission (CR) were given another 2 cycles of post-remission therapy with cytarabine. Each chemotherapy regimen was followed by donor stem cell infusion in the MST groups. ResultMST achieved an encouragingly high CR rate in patients (63.8%), even in high-risk patients (54%). It was significantly higher than that in the chemotherapy alone group. The 1-year overall survival (OS) of MST patients was 57.7% and was 68.6% in the high-risk and standard group, respectively, whereas the OS was only 37.3% in the chemotherapy group. The severe infection rate was 36% and 54% in MST and chemotherapy group. No GVHD was observed in MST patients. A larger updated T cell clones was observed in MST patients by T cell receptor repertoire analysis with a Next Generation Sequencing methodology. ConclusionsThese results suggested that MST is a safe and practical treatment regimen conducive to a longer-term survival for AML patients at a highly advanced age.