At a dose of 1000 pg/ml, GO killing of ML-1 (AML) cells decreased from 56±5% (mean±SEM) in parental cells to 32±7% (p<0.01) and 26±6% (p<0.01) in cells overexpressing BCL-2 and BCL-XL, respectively (all n=3)…AZD5991 modestly increased the anti-leukemic efficacy of GO in ML-1 cells and AML patient specimens, but more dramatically enhanced IO killing of REH cells (IO at 10 pg/ml....though the triplet combination of IO, ABT-199 and AZD5991 showed promising activity: in REH cells treated with 10 pg/ml IO, cytotoxicity was 18±2% without BCLi, 32±8% with ABT-199 0.1 µM, 19±2% with AZD5991 0.01 µM, and 56±14% with the triplet combination (p<0.01 for comparison of triplet combination with IO/BCLi doublet).