As₂O₃: an inorganic arsenic compound; a by-product of metal smelting operations.
This small-molecule arsenic compound shows antineoplastic activity. The mechanism of action of arsenic trioxide is not completely understood. This agent causes damage to or degradation of the promyelocytic leukemia protein/retinoic acid receptor-alpha (PML/RARa) fusion protein; induces apoptosis in acute promyelocytic leukemia (APL) cells and in many other tumor cell types; promotes cell differentiation and suppresses cell proliferation in many different tumor cell types; and is pro-angiogenic.