An orally bioavailable capsule formulation of the inorganic toxic compound arsenic trioxide (As2O3), with potential antineoplastic activity. Although the mechanism of action (MoA) of As2O3 is not well understood, upon oral administration of ORH 2014, As2O3 appears to bind to DNA, prevent DNA synthesis, and cause DNA fragmentation, which leads to an induction of apoptosis in proliferating cells, including tumor cells. In addition, As2O3 causes damage to and induces degradation of the promyelocytic leukemia protein/retinoic acid receptor-alpha (PML/RARa) fusion protein, and inhibits the activity of the enzyme thioredoxin reductase.