Analysis of correlations between etoposide-induced DDR nodes in AML samples highlights unique patient biology. Primary AML (PBMC and BMMC) samples were treated with 30 μg/ml etoposide for 2 hr or 6 hr and the modulation of a panel of DDR readouts was measured (p-53BP1, p-ATM, p-BRCA1, p-DNA-PKcs, p-H2AX). (A) Flow plots illustrating the gating scheme for leukemic cells and lymphocytes from AML samples (left) and etoposide induced DDR responses in leukemic cells for p-H2AX, p-DNA-PKcs, p-p53, p-ATM, p-53BP1, p-Chk2 and p-BRCA1 (right). (B) Individual modulated DDR readouts were then compared to each other with bivariate plots, with R2 values shown. While higher correlations were observed between the DSB response (p-ATM) and HRR pathways (p-BRCA1) (left scatter plot), and between measures of DNA damage (p-H2AX) and NHEJ repair (p-DNA-PKcs) (middle scatter plot), lower correlations were observed across pathways comparing HRR (p-BRCA1) and NHEJ (p-DNA-PKcs) readouts (right scatter plot). Samples enclosed by a red circle demonstrate relatively higher activation of NHEJ pathway components (p-DNA-PKcs) as compared to HRR pathway components (p-BRCA1). (C) Correlation R2 values between etoposide induced DDR readouts at 2 h and 6 h.