Arsenic trioxide: a new immunomodulatory agent in the management of multiple myeloma.

Arsenic has been used as a medicinal for thousands of years. Several reports from China relative to its use mainly in acute promyelocytic leukemia, especially from the Shanghai group, has caused a resurgence in the investigation of the drug in the management of malignancies with focus on malignancies of hematologic origin. Arsenic is eliminated by many routes (urine, feces, sweat, milk, hair, skin, and lungs), although most is ultimately excreted in urine. Multiple myeloma is characterized by the clonal proliferation of malignant plasma cells in the bone marrow associated with bone loss, renal disease, and immunodeficiency. Preclinical evidence suggests an immunologic mechanism behind the therapeutic effects of As2O3 on myeloma cells. This appears to be achieved by a marked increase in lymphokine-activated killers mediated killing and up-modulation of CD38 and Cd54, two molecules involved in cell-cell interactions. Moreover, As2O3 alone or administered with ascorbic acid may provide a novel therapy for lymphoproliferative disorders. Preliminary clinical data in relapsed/refractory multiple myeloma suggest that As2O3 does have a role in the management of multiple myeloma; however, preclinical data show that the addition of ascorbic acid, and using As2O3 in combination with other active chemotherapeutic agents will enhance its role in managing the disease, and this is probably the position the drug will occupy in the armamentarium against myeloma.