Statistical analysis
Data were analyzed with the support of two biostatisticians (ZZ and YL) at the Children’s Hospital of Philadelphia. Demographic and clinical characteristics were summarized for the overall cohort and by presence or absence of KMP using descriptive statistics. Outcome variables including response rates (e.g., objective hematologic response at 3 months), durability of response (e.g., time to persistent disease from objective hematologic response), and adverse events were summarized overall and by treatment groups. For group (either KMP or treatment groups) comparisons, Wilcoxon rank sum test was used for continuous variables and Fisher’s exact test was used for categorical variables. All analyses were performed in R 3.6.3 and a two-sided p-value < 0.05 was considered statistically significant.