Arsenic trioxide (As<sub>2</sub>0<sub>3</sub>) is an arsenic-derivative that exhibits potent growth inhibitory effects against malignant cells. The remarkable antitumor effects of As<sub>2</sub>0<sub>3</sub> in vitro and in vivo have prompted the development of various clinical trials that established its activity in acute promyelocytic leukemia (APL). As<sub>2</sub>0<sub>3</sub> is part of the standard treatment...