Guo M, et al. - Researchers aimed at evaluating outcomes in different age groups among older patients with newly diagnosed acute myeloid leukemia (AML) who receive HLA-mismatched microtransplant. Based on the findings, they conclude that for older patients with acute myeloid leukemia, microtransplant provided an effective and safe therapy.

Methods

• Researchers performed this multicenter clinical study including 185 patients with de novo AML at 12 centers in China, the United States, and Spain in the Microtransplantation Interest Group.
• They divided patients into the following 4 age groups: 60 to 64 years, 65 to 69 years, 70 to 74 years, and 75 to 85 years.
• From May 1, 2006, to July 31, 2015, this study was performed.
• Patients received induction chemotherapy and postremission therapy with cytarabine hydrochloride with or without anthracycline, followed by highly HLA-mismatched related or fully mismatched unrelated donor cell infusion.
• They used no graft-vs-host disease prophylaxis.
• The complete remission rates, leukemia-free survival, and overall survival in different age groups were evaluated as the primary end point of the study.
• Hematopoietic recovery, graft-vs-host disease, relapse rate, nonrelapse mortality, and other treatment-related toxicities were assessed as the additional end points of the study.

Results

• Researchers noticed that the median age of the included patients was 67 years (range, 60-85 years), and 75 (40.5%) were female.
• In adjusted percentages in overall survival, leukemia-free survival, relapse, and nonrelapse mortality, the denominators were not the sample proportions of observations.
• Among the 4 age groups, no significant differences in the overall complete remission rate was observed (75.4% [52 of 69], 70.2% [33 of 47], 79.1% [34 of 43], and 73.1% [19 of 26).
• The first 3 age groups showed the 1-year overall survival rates of 87.7%, 85.8%, and 77.8%, these were much higher than the rate in the fourth age group (51.7%) (P=.004, P=.008, and P=.04, respectively).
• The first 2 age groups showed the 2-year overall survival rates of 63.7% and 66.8%, these were higher than the rates in the last 2 age groups (34.2% and 14.8%) (P=.02, P=.03, P < .001, and P < .001, respectively).
• The 1-year cumulative incidences of nonrelapse mortality, in the 4 age groups, were 10.2%, 0%, 3.4%, and 26.0%, respectively, and 8.1% in all patients.
• After induction chemotherapy, the median times to neutrophil and platelet recovery were 12 days and 14 days, respectively.
• In this study, 5 patients had full or mixed donor engraftment, and 30.8% (8 of 26) of patients demonstrated donor microchimerism.
• Severe acute graft-vs-host disease developed in 2 patients (1.1%).