A drug from poison: how the therapeutic effect of arsenic trioxide on acute promyelocytic leukemia was discovered.

It is surprising that, while arsenic trioxide (ATO) is now considered as "the single most active agent in patients with acute promyelocytic leukemia (APL)", the most important discoverer remains obscure and his original papers have not been cited by a single English paper. The discovery was made during the Cultural Revolution when most Chinese scientists and doctors struggled to survive. Beginning with recipes from a countryside practitioner that were vague in applicable diseases, Zhang TingDong and colleagues proposed in the 1970s that a single chemical in the recipe is most effective and that its target is APL. More than 20 years of work by Zhang and colleagues eliminated the confusions about whether and how ATO can be used effectively. Other researchers, first in China and then in the West, followed his lead. Retrospective analysis of data from his own group proved that APL was indeed the most sensitive target. Removal of a trace amount of mercury chloride from the recipe by another group in his hospital proved that only ATO was required. Publication of Western replication in 1998 made the therapy widely accepted, though neither Western, nor Chinese authors of English papers on ATO cited Zhang's papers in the 1970s. This article focuses on the early papers of Zhang, but also suggests it worth further work to validate Chinese reports of ATO treatment of other cancers, and infers that some findings published in Chinese journals are of considerable value to patients and that doctors from other countries can benefit from the clinical experience of Chinese doctors with the largest population of patients.