Minimal residual disease (MRD) has been used for warning of relapse and guiding the therapy selection for hematological malignancies including acute leukemia. Based on MRD-related content reported at the 64th American Society of Hematology (ASH) Annual Meeting, this article discusses the progress of MRD-directed individualized therapy for hematological malignancies with a primary focus on acute myeloid leukemia.

Objective:To investigate the role of short-term use of mycophenolate mofetil (MMF) in EB viral infection and acute graft-versus host disease (GVHD) in patients receiving haploidentical hematopoietic stem cell transplantation (haplo-HSCT) .Method:Adult patients (≥14 years) who were diagnosed with hematological malignancies received haplo-HSCT in Peking University Institute of Hematology from May 2016 to December 2017 were retrospectively reviewed. The median age was 30 (14-60) years old. A total of 498 patients including 277 males and 221 females were enrolled. Donors' median age was 38 (8-66) years old. All patients were classified into long-term use of MMF ( n=199), which was defined as 500 mg every 12 hours from day 9 pre-transplant to 250 mg every 12 hours from day 30 after transplant then withdrawal on day 45 to 60 after transplant, and short-term use of MMF ( n=299), which was defined as 500 mg every 12 hour from day 9 pre-transplant then withdrawal till neutrophil engraftment. Kaplan-Meier model was used to analyze the cumulative incidence of EBV infection, and the Cox proportional regression model for multivariate analysis. Result:Characteristics including sex, age, disease types, mismatched HLA loci, donor-recipient relationship, donor-recipient blood type, donor age, and donor sex were comparable between two groups (all P＞0.05). According to once, the incidence of EBV viremia, defined as EBV＞10 3 copies/ml at least once, in short-term group and long-term group was 19.4% (58/299) and 27.6% (55/199) respectively ( P=0.046).Donor age and the duration of MMF prophylaxis (short-term group as reference) were associated with EBV viremia according to multivariate analysis [ HR=1.022(95% CI 1.006-1.038),1.600(95% CI 1.059-2.418); P=0.006 and 0.026, respectively]. The incidence of grade Ⅱ-Ⅳ and Ⅲ/Ⅳ acute GVHD in long-term and short-term group was 32.2% (64/199) versus 20.7% (62/299)( P=0.005) and 10.1% (20/199) versus 8.0% (24/299) ( P=0.427), respectively. Donor sex (female as reference) and duration of MMF prophylaxis (short-term group as reference) were associated with grade Ⅱ-Ⅳ acute GVHD [ HR=1.908(95% CI 1.079-3.373),1.752(95% CI 1.161-2.643); P=0.026 and 0.008, respectively].There were no statistical differences in the incidence of CMV viremia, refractory CMV viremia and hemorrhagic cystitis (all P＞0.05) between the two groups. Conclusion:Short-term use of MMF can reduce EBV viremia without increasing the development of acute GVHD in haplo-HSCT patients.