Oral arsenic trioxide was first used in the Department of Medicine, Queen Mary Hospital (QMH), as a treatment of leukemia in the late 1940s and early 1950s. However, newer drugs phased out oral arsenic trioxide, and its use was forgotten for nearly half a century. In 1998, a small team of medical researchers at the Department of Medicine, Queen Mary Hospital, began investigating the use of oral arsenic in the treatment of blood cancers, based on the successful use of intravenous arsenic trioxide in the treatment of acute promyelocytic leukaemia. To determine the dosage and safety of oral arsenic, the QMH team initially turned to archival medical records retrieved from the Hong Kong Medical Museum. This was followed by two years of research into the methods of preparation of the oral formulation.


In 2000, the team successfully prepared an oral formulation of arsenic that was tested in a clinical study in blood cancer treatment. With its demonstrated clinical efficacy, a US patent has been granted (US Patent Number: 7,521,071).