[Clinical Efficacy and Survival Analysis of Adult Patients with Acute Myeloid Leukemia after Microtransplantation]

Objective: To investigate the clinical efficacy and survival factors of microtransplantation (MST) in adult patients with acute myeloid leukemia (AML).

Methods: For a retrospective analysis of 27 adult patients with AML receiving MST from July 2014 to October 2021, the median age was 59(29-77) years old, 13 cases were ≥60 years old, 14 case were <60 years old, 13 cases were male and 14 cases were female. Classification by FAB: AML-M2 6 cases, AML-M4 6 cases, AML-M5 2 cases, AML-M6 2 cases, AML（Undivided type） 9 cases, AML myeloid sarcoma 2 cases (primary AML 21 cases, AML secondary to MDS 6 cases). Cytogenetic analysis showed 25 patients with a normal karyotype, 2 patients with an abnormal karyotype, and 20 patients with an abnormal molecular biology. Induction chemotherapy regimens mainly include: IA, DA, MA or HA regimen, including CAG or CIG in combination with decitabine, and single-agent decitabine. 17 patients achieved complete remission (CR) after 1 course of induction chemotherapy and 4 patients achieved CR after 2 courses of induction chemotherapy. 3 patients received CR by four courses of decitabine, 2 patients received no remission, and 1 patient underwent no induction chemotherapy and were treated direct MST. There were 16 patients with pretransplant CR and 11 patients were not in remission before transplantation. Follow-up mainly used consult patient's medical records and telephone inquiry to observe the adverse effects and efficacy of MST treatment. Survival analysis was performed by Kaplan-Meier method, with the main observation indicators overall survival(OS) and leukemia-free survival(LFS), and performed with the Log-rank test. Multivariate analysis was performed by the Cox regression model.

Results: A total of 79 MST were performed in 27 AML patients with good overall safety and no special serious adverse effects. The median time of leukocyte recovery was 13(4-28) days, and the median time of platelet recovery was 13(4-30) days. There were 50 cases of infection, 5 cases of abnormal liver function and 3 cases of abnormal cardiac function. Except for abnormal cardiac function, all other complications did not affect the treatment and were cure. Acute or chronic GVHD, renal insufficiency, abnormal coagulation function, and severe bleeding were not observed during treatment or during follow-up. As of the follow-up date, the median follow-up time of the 27 patients was 79(14-171) months, the median OS time was 62(1-171) months, and the median LFS time was 15(0-171) months. The 2-year OS rate was 65.7%（17/27）, and the 2-year LFS rate was 47.4%（12/27） . The complete response rate of 27 patients treated with MST was 48.1% (13/27). 8 patients relapsed during MST treatment, including 7 patients after the completion of the first MST course and 1 patient after the completion of the second MST course. 2 patients relapsed after the end of the course of MST. 13 patients died, including 10 patients because of disease progression, two patients from severe infection, and one patient from cardiac damage.

Conclusion: MST has the advantages of small toxic side effects, complete compatibility of HLA matching is not required, effective avoidance of GVHD and rapid hematopoietic recovery, which can improve OS and LFS in elderly AML and young AML patients, and is one of the treatment options for patients without HLA matching.