We first used nanoparticle tracking analysis (NTA) to determine if the size or concentration of EVs differed in the PB plasma of newly diagnosed pediatric B-ALL (n=8, 3 ETV6::RUNX1, 3 BCR::ABL1-like) and NCD (n=6) at diagnosis. The gene discussed is RUNX1; the disease is precursor B-cell acute lymphoblastic leukemia.