There is a well documented relationship between the use of arsenic trioxide and a cardiovascular side-effect, prolongation of the QT interval, which can lead to a potentially fatal torsade de pointes-type ventricular arrhythmia. Indeed, this is described in a black box warning in the label for Cell Therapeutics Inc.'s Trisenox arsenic trioxide to treat relapsed or refractory acute promyelocytic leukemia (APL).

New data published in Blood by researchers at Our Lady of Mercy Cancer Center (New York, N.Y