Regarding children's patients undergoing allogeneic hematopoietic stem cell transplant (HSCT) for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS), disease relapse remains the most common reason for transplant failure and patient death. We implemented a single center study to investigate hypomethylating agents (HMA) as maintenance treatment after HSCT for children AML or MDS. We retrospectively analyzed 30 patients with AML or MDS including 63 courses of azacytidine (AZA) and 69 courses of decitabine (DEC) from January 1, 2018 to June 30, 2021 (Figure 1A). Either AZA (37.5mg/m 2 to 75 mg/m 2 for consecutive 5-7 days) or DEC (5 mg/m 2 for consecutive 5 days) was administrated 90 days post-transplantation as first course. Furthermore, the interval of HMA treatment was 1.5-month hereafter for in total of a year (Figure 1B). Patients that received at least one course of HMA treatment were included in this study. The patient characteristics was shown in Table 1. We found that the disease-free survival (DFS) and overall survival (OS) were 82.96±6.95% and 85.51±6.72%, respectively (Figure 1C, D). Based on Common Terminology Criteria for Adverse Events (CTCAE) criteria, only Grade 1 to 2 leukopenia (P<0.001), anemia (P=0.043), and thrombocytopenia (P=0.033) were found between complete blood count (CBC) of pre-treatment and post-treatment. Subgroup analysis indicated that the difference was mainly come from DEC group [leukopenia (P<0.001), anemia (P=0.001), and thrombocytopenia (P=0.190)] instead of AZA group [leukopenia (P=0.476), anemia (P=0.443), and thrombocytopenia (P=0.095)]. No nausea/vomiting, or elevated ALT, or elevated creatinine, or rash, or de novo/exacerbated GVHD were observed. Moreover, there were no difference of activation T cells populations (CD25 and HLA-DR) among 7 courses except CD3+HLADR+/CD3+ and CD8+HLADR+/CD8+ in course 1 vs course 4 (P= 0.0354 and P=0.0163, respectively, Figure 1E). Furthermore, a trend of increased percentage of CD3+HLADR+/CD3+, or CD4+HLADR+/CD4+, or CD8+HLADR+/CD8+ and decreased percentage of CD3+CD25+/CD3+, or CD4+CD25+/CD4+, or CD8+CD25+/CD8+ was found in relapsed group, despite there was no significant difference. Interestingly, DEC significantly reduced population of CD3+HLADR+/CD3+, or CD4+HLADR+/CD4+, or CD8+HLADR+/CD8+ compared to AZA (P<0.001, P<0.001, or P<0.001, respectively). In conclusion, both AZA and DEC as HMA maintenance treatment following HSCT in children AML or MDS was safe, and the outcome was encouraging. A further large cohort of randomization of AZA and DEC study is required.

Figure 1
Figure 1.
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Disclosures

No relevant conflicts of interest to declare.

© 2021 by The American Society of Hematology
2021
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