The Native Environment (NE) recapitulates naïve tumor behavior and promotes realistic drug responses. NE contains key factors such as tumor-stromal interactions, plasma, platelets, or red blood cells (RBC) that will influence the clinical efficacy of many drugs. The PharmaFlow platform allows us to aspirate the same exact volume and content of each well from a 96 well-plate to the flow of the cytometer. The combination of fluorescently labeled antibodies to identify leukemic cells and Annexin-V staining to exclude dying cells, allows us to measure differences in the number of live leukemic cells in a well with drugs vs. the control wells. In this way, the PharmaFlow platform can quantify the activity for all those drugs that produce programmed cell death or a reduction in the number of target cells.