8-Chloroadenosine-5’-triphosphate (8-chloro ATP), a potent metabolite of the anticancer agent 8-chloro cyclic AMP (cAMP) and a nucleotide derivative, is produced through the biotransformation of 8-chloro cAMP into 8-chloroadenosine, followed by mono- and diphosphate intermediates. Accumulating for up to 12 hours after the administration of 8-chloro cAMP or 8-chloroadenosine, 8-chloro ATP inhibits cell growth, diminishes endogenous ATP levels, and reduces RNA synthesis without affecting DNA synthesis in multiple myeloma cells derived from patients. Moreover, it obstructs topoisomerase II-α-mediated relaxation of supercoiled pUC19 DNA at concentrations ranging from 1.5 to 8 mM and decreases topoisomerase II-α-enhanced ATP hydrolysis by 50% at a concentration of 1 mM in K562 human myelocytic leukemia cells.