Background: Relapse remains a major challenge in pediatric acute myeloid leukemia (AML), particularly in non-transplant-eligible patients. Although hypomethylating agents, such as azacitidine, are hypothesized to target residual disease, their efficacy and safety in de novo pediatric AML maintenance therapy require validation. Procedure: In this retrospective cohort study, 78 pediatric patients with de novo AML in remission after the C-HUANAN-AML 15 protocol were stratified into azacitidine maintenance (n=27; subcutaneous 75 mg/m 2/day, days 1–14/cycle for 6 cycles) or observation (n=51) groups. Measurable residual disease (MRD) was longitudinally monitored using multiparameter flow cytometry (<0.1% threshold) and PCR for fusion transcripts. Outcomes included disease-free survival (DFS), overall survival (OS), and safety. Results: At a median 34.6-month follow-up, azacitidine maintenance therapy showed comparable OS (89.7% vs. 85.0%, p=0.368) and DFS (77.7% vs. 79.0%, p=0.838) to observation overall. However, intermediate-risk patients exhibited improved DFS (85.1% vs. 73.1%, p=0.305) and OS (92.9% vs. 81.6%, p=0.304). In core-binding factor-AML with baseline fusion transcripts ≥0.1%, azacitidine significantly prolonged DFS (100% vs. 62.5%, p=0.045). MRD negativity persisted in 92.6% of the azacitidine-treated patients, with one molecular relapse (0.02% blasts). Therapy was well tolerated: 40.7% had grade 2–4 myelosuppression, but all patients completed the treatment without dose reductions. Conclusions: Azacitidine maintenance is safe and is associated with sustained MRD suppression in pediatric AML, particularly in the intermediate-risk and molecularly persistent core-binding factor-AML subgroups. These findings support the use of risk-adapted MRD-guided maintenance strategies to reduce relapse and warrant validation in larger cohorts.

Background: Many cytogenetic changes and gene mutations are associated with acute myeloid leukaemia (AML) survival outcomes. CD56 is related to poor prognosis when expressed in adult AML. The prognostic value of CD56 in children with AML has rarely been reported. Procedure: To evaluate the prognostic value of CD56 in childhood AML, multicentric retrospective study included 224 paediatric patients in two hospitals between January 2015 and April 2021. Results: The median (range) age was 75 (8-176) months, and the median follow-up time was 31 months. There was no significant difference in the 3-year overall survival rate between the CD56-positive and CD56-negative groups (78.4% vs. 73.3%, P=0.496). For patients who received haematopoietic stem cell transplantation, there was no significant difference in the 3-year overall survival rate between the CD56-positive and CD56-negative groups (59% vs. 63.9%, P=0.922). Multivariate analysis showed that CD56 positivity was not an independent prognostic factor for childhood AML (hazard ratio 0.85, P=0.648). Furthermore, in children with AML, CD56 positivity was more likely to be associated with the CBFβ-MYH11 mutation and mixed lineage leukaemia gene rearrangement. Conclusions: In summary, we demonstrated that CD56 cannot be used as a factor to predict the prognosis of children with AML.

Backgroud: Tyrosine kinase inhibitors (TKIs) has gradually replaced HSCT as the first-line treatment for pediatric patients with chronic-phase Chronic myeloid leukemia (CML-CP). However, there are few reports detailing the long-term effect and safety of TKIs in Chinese children with CML-CP. Procedure: A total of 58 patients (43 children and 15 adolescents) with newly diagnosed CML-CP received imatinib mesylate (IM) as first-line therapy and 2G-TKIs as second-line therapy. The responses and safety to TKI therapy, and the rates of overall survival (OS), progression-free survival (PFS) and event-free survival (EFS) were assessed. Results: After 3 months of IM treatment, 91.4% (53/58) of patients achieved complete hematologic response (CHR). Fifty-one patients received further IM treatment for up to 12 months, and 88.2% (45/51) of them achieved major cytogenetic response (MCyR), with 68.6% (35/51) achieving complete cytogenetic response (CCyR). The cumulative incidence of achieving major molecular response (MMR) was 45.1% (23/51) and 66.0% (31/47) after 12 months and 18 months from initial IM treatment, respectively. Sixteen patients were switched to second-generation TKIs (2G-TKIs), dasatinib (n=8) and nilobinib (n=8), due to lack of response to IM treatment. Among them, 11 patients (68.8%) achieved MMR at a median time of 3.7 months. With a median follow-up duration of 44.8 months, the 9-year overall survival rate (OS) was 81.1%, the 9-year progression-free survival rate (PFS) was 80.5%, and the 9-year event-free survival rate (EFS) was 44.4%. Conclusion: IM as first-line therapy and 2G-TKI as second-line therapy are effective long-term therapeutic measures for children and adolescents in CML-CP.