The present invention provides methods of treatment for hematological malignancies involving synergistic combination of a proteasome inhibitor, a glucocorticoid, an arsenic-containing compound, and ascorbic acid or a derivative thereof provide an unexpected efficacy in the treatment for hematological disorders. The hematological disorders treated by the current invention include multiple myeloma, and may also include hematological disorders that are refractory to prior cancer treatments, or relapsed hematologic disorders.
