KMT2A and cancer: Figure 1A represents an overview of the preclinical model. NSG mice were inoculated with MLL-1, MLL-2, or MLL-7 PDX cells and disease burden was assessed weekly by flow cytometry analysis of the % huCD45+ as well as cfDNA and ctDNA detection using Tapestation and ddPCR, respectively. Human cancer DNA can be easily discriminated from host mouse DNA in PDX models by targeting human cancer-specific sequences such as chromosomal translocations through qPCR [27]. Each qPCR assay conformed to the standardized EuroMRD guidelines (Figure 1B, Supplementary Figure S1) [4].