FLT3 and acute lymphoblastic leukemia: While the KT-16 PDX response remains unexplained, as mentioned above, ALL-2 harbors a mutation in the first amino acid of the FLT3 juxtamembrane domain (Y572S, 0.62 VAF) that is predicted to be activating and was associated with high FLT3 mRNA expression in this model (Dolai et al., 2016).