Supplementary Material for: Prognostic Factors, FLT-3 Mutations, and Treatment Outcomes with pediatric inspired protocols in adolescent and young adults (AYA) and adult patients with Acute Lymphoblastic Leukemia

Introduction: The treatment protocols of adolescent and young adults (AYA) patients with acute lymphoblastic leukemia (ALL) have evolved, with the advent of pediatric-based regimens, measurable residual disease monitoring and mutation analysis. Among the latter, previous reports have identified FLT-3 mutations in up to 5% of pediatric patients, however the full clinical significance of these mutations in the non-pediatric population is still uncertain. Methods: Our cohort includes AYA patients with ALL treated with the NY-II and BFM protocols at different time periods, allowing analysis of prognostic factors and survival outcomes. Additionally, we analyzed DNA samples for FLT-3 mutations, focusing on the potential prognostic implications and treatment responses within our cohort. Results: No significant differences were found in overall survival (OS) or progression-free survival (PFS) between the two treatment protocols. However, a higher rate of hematopoietic stem-cell transplantation (HSCT) was noted in the NY-II patients. Older age and high WBC count at presentation were identified as adverse prognostic factors using multivariate analysis. FLT-3 mutations were identified in 4 patients (5%) of the cohort, with only one patient having FLT-3 internal tandem duplication (ITD) mutation and three patients having FLT-3-tyrosine kinase domain (TKD) mutations. Conclusions: The low rate and variability of FLT-3 mutations in an Israeli cohort precludes broad conclusions regarding their prognostic significance. In our cohort, age and WBC count, but not treatment protocol or FLT-3 mutations influenced survival.