Data presented at the Joint International Congress on Acute Promyelocytic Leukemia and Differentiation Therapy demonstrated that patients with acute promyelocytic leukemia (APL) treated with arsenic trioxide(Drug information on arsenic trioxide) achieved an overall survival at 24 months of 63%.
"Trisenox is a major medical breakthrough for the thousands of relapsed APL patients whose previous treatments were unsuccessful," said Steven L. Soignet, MD, principal investigator of the arsenic trioxide pilot and pivotal clinical trials. "The high rate of complete remission and relapse-free survival associated with the use of this drug is very encouraging news for this patient population, which traditionally has had a very poor prognosis."
The data on arsenic trioxide presented at this meeting combines the results of two clinical studies that enrolled 52 patients with a median age of 39 years. One study was a pilot study in 12 patients with relapsed APL conducted at Memorial Sloan-Kettering Cancer Center, and the other, a 40-patient pivotal trial conducted at nine medical centers across the United States. The results of the larger trial were published in a recent issue of the Journal of Clinical Oncology (9:3852-3860, 2001).
Patients were treated with 1- to 2-hour infusions of arsenic trioxide daily until the time of bone marrow complete remission. Those who experienced a complete response were offered one consolidation course of arsenic trioxide that began 3 to 4 weeks later. Patients who maintained a complete response were eligible to receive additional cycles of arsenic trioxide in a maintenance study, and some patients underwent transplants.
A total of 45 patients achieved a complete remission, for an overall response rate of 87%, with a 2-year relapse-free survival rate of 49%. Toxicities were manageable, and there were no treatment-related deaths during the study.
"These results confirm Trisenox as a highly effective therapy for patients with APL in whom standard treatments have failed," said Martin S. Tallman, MD, associate professor of Medicine at Northwestern University Medical School. "They are particularly important because few treatment options have been available for patients with relapsed disease."