Multiplexed mAb imaging predicts chemotherapy responses in primary patient xenografts of AML. NSG mice (n = 16) injected with AML cells (5 × 10⁶) from patient 5 were treated with Ara-C (500 mg/kg) for 2 days in combination with daunorubicin (2.5 mg/kg) for 3 days. Imaging with multiplexed mAbs was performed before initiation of therapy (day 21) and 1 week later (day 28). (A-B) Representative images of mice after treatment reveal a significant reduction (P < .0008) in total fluorescence of treated mice compared with vehicle controls. After imaging on day 28, mice (n = 4 per group) were killed and femoral BM was recovered for flow cytometry analysis of human AML cells (C-D). Significantly reduced human (CD45⁺; P < .05) and leukemic stem cell populations (CD34⁺CD33⁺; P < .01) were noted in treated mice. (E) The remaining mice were euthanized when moribund after institutional guidelines; treated mice (n = 4) demonstrated significant increases in survival (P = .007) over controls (n = 4).