Swallowing a bitter pill–oral arsenic trioxide for acute promyelocytic leukemia

Parenteral arsenic trioxide (ATO) has been firmly established as a standard therapy for acute promyelocytic leukemia (APL). Despite widespread use of oral arsenicals in medicine historically, they had disappeared from modern pharmacopeia until oral ATO was redeveloped in Hong Kong in 2000. Since then, over 200 patients with leukemia (predominantly APL) have been treated with oral ATO in Hong Kong and China. Oral arsenic trioxide and other formulations of arsenic appear to have a clinical efficacy comparable to that of IV formulations. These drugs given orally also appear to have a slightly better safety profile, lower operational costs and improved convenience for patients. The clinical experience with oral ATO has previously been reported piecemeal as case series, pilot studies or subgroup analyses rather than in a comprehensive cohort. In this report we attempt to synthesize the published English language literature on oral arsenicals and present the argument for further development of these compounds. Systematic study of this drug with well-designed randomized multi-center clinical trials is needed to accelerate its development and incorporation into clinical practice.