Here we report that DS/Cu is significantly and selectively cytotoxic in vitro against human B-ALL cell lines and primary samples obtained from adults with B-ALL, particularly those carrying adverse prognostic genetic abnormalities (e.g., p16 deletion), as well as effective in vivo in B-ALL patient-derived xenografts, in association with activation of the intrinsic apoptotic pathway, at least in part, due to down-regulation of Bcl-2 and Bcl-xL. This evidence concerns the gene BCL2 and precursor B-cell acute lymphoblastic leukemia.