Single Agent Arsenic Trioxide in the Treatment of Newly Diagnosed Acute Promyelocytic Leukemia (IAPLSG04)

There is very limited data on the use of arsenic trioxide in newly diagnosed patients with acute promyelocytic leukemia. The use of arsenic trioxide was limited to relapsed patients mainly because of the superior efficacy of ATRA as primary therapy for newly diagnosed APML. Though the early study by Niu et al showed 72% remission rates in 11 newly diagnosed patients, the role of arsenic trioxide as primary therapy was limited by the hepatic toxicity seen in this study. Studies from our centre have shown remission rates of 70-75% in newly diagnosed patients with acute promyelocytic leukemia. There was no major toxicity seen related to the administration of arsenic trioxide. Follow up data on these patients continue to show long term remission rates above 70%. These remission rates are similar to the data available in patients with acute promyelocytic leukemia treated with ATRA. Lu et al studied 19 patients treated with oral arsenic (Tetra-arsenic tetra-sulfide) wherein 84% achieved hematological remission with disease free survival of 76% at 3 years. Studies from other groups using arsenic trioxide alone or in combination with ATRA have shown similar remission rates. Arsenic trioxide as primary therapy for patients with newly diagnosed acute promyelocytic leukemia is a very attractive treatment option for developing countries mainly because of the low cost involved along with the favorable toxicity profile. However long term remission data is still not available and the ideal course and duration of treatment still needs to be defined. This multi-center study aims to further clarify the efficacy of this agent in the treatment of newly diagnosed cases of acute promyelocytic leukemia and to study the optimal maintenance regimen.