CYTOGENETIC CHARACTERISTICS AND TREATMENT OUTCOMES OF CONGENITAL ACUTE LEUKEMIA IN CHILDREN IN KAZAKHSTAN: retrospective study

Background: Congenital acute leukemia (CAL) is a rare and aggressive hematologic malignancy diagnosed within the first 28 days of life. Cytogenetic abnormalities are essential for risk stratification and prognosis, but data on CAL in Kazakhstan remain limited.
Objective: To describe cytogenetic characteristics and evaluate their association with treatment outcomes in children with congenital and early infant acute leukemia treated at a tertiary pediatric center in Kazakhstan.
Materials and Methods: This retrospective single-center study included 33 children treated between 2018 and 2023 at the Scientific Center of Pediatrics and Pediatric Surgery (Almaty, Kazakhstan). Patients were classified as true CAL (diagnosis ≤28 days) or early infant leukemia (>28 days). Cytogenetic findings, treatment protocols, remission, relapse, mortality, treatment-related toxicity, and survival were analyzed. Overall survival (OS) and event-free survival (EFS) were assessed using the Kaplan–Meier method.
Results: Cytogenetic abnormalities were detected in 17/33 patients (51.5%). Favorable abnormalities included t(12;21), t(8;21), and inv(16), whereas unfavorable abnormalities included t(4;11)/KMT2A-rearranged leukemia and t(9;22). Complete remission after induction was achieved in 66.7% of patients and was significantly more frequent in the favorable cytogenetic group than in the unfavorable group (91.6% vs. 58.3%; p = 0.019). Treatment-related toxicity occurred in 42.4% of patients and was more common among those with non-complete remission (83.3% vs. 31.8%; p = 0.017). Estimated 2-year OS was 83.3% in the favorable cytogenetic group and 50.0% in the unfavorable group, while estimated 2-year EFS was 75.0% and 41.7%, respectively. Survival differed significantly according to cytogenetic risk (log-rank p = 0.032 for OS; p = 0.021 for EFS).
Conclusion: Congenital and early infant acute leukemia in this single-center cohort from Kazakhstan demonstrated substantial cytogenetic heterogeneity associated with remission and survival outcomes. Cytogenetic-based risk stratification and careful management of treatment-related toxicity may improve outcomes in this vulnerable patient population.