Phase II Study of Melphalan, Arsenic Trioxide, and Ascorbic Acid in Patients With Relapsed or Refractory Multiple Myeloma

DISEASE CHARACTERISTICS: Diagnosis of multiple myeloma meeting at least 1 of the following criteria: Relapsed disease after a response to standard first-line chemotherapy (e.g., vincristine, doxorubicin, and dexamethasone [VAD] OR melphalan and prednisone) or first-line high-dose chemotherapy Refractory disease (failed to achieve at least stable disease) to most recent chemotherapy with or without systemic corticosteroids Measurable disease, defined as a monoclonal immunoglobulin spike on serum electrophoresis of ≥ 1 g/dL AND/OR urine monoclonal immunoglobulin spike of ≥ 200 mg/24 hours No non-secretory myeloma No plasma cell leukemia PATIENT CHARACTERISTICS: Age 18 and over Performance status Karnofsky 60-100% Life expectancy More than 3 months Hematopoietic Platelet count ≥ 50,000/mm^3 (30,000/mm^3 if bone marrow is extensively infiltrated) Hemoglobin ≥ 8.0 g/dL Absolute neutrophil count ≥ 1,000/mm^3 Pancytopenia secondary to multiple myeloma or hypersplenism allowed Hepatic AST and ALT ≤ 3 times upper limit of normal (ULN) Bilirubin ≤ 2 times ULN (unless clearly related to disease) No known active hepatitis B or C infection Renal Calcium < 14 mg/dL Cardiovascular No evidence of acute ischemia or new conduction system abnormality by electrocardiogram No myocardial infarction within the past 6 months No New York Heart Association class III or IV heart failure No poorly controlled hypertension No prolonged corrected QT interval (> 460 ms) with potassium > 4 mmol/L and magnesium ≥ 1.8 mmol/L Other No active infection No POEMS syndrome (plasma cell dyscrasia with polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes) No diabetes mellitus No other serious medical or psychiatric illness that would preclude study participation No known allergic reaction attributable to compounds of similar chemical or biological composition to study drugs No history of grand mal seizures HIV negative Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy More than 4 weeks since prior immunotherapy or antibody therapy Chemotherapy See Disease Characteristics More than 3 weeks since prior chemotherapy (6 weeks for nitrosoureas) Endocrine therapy See Disease Characteristics No other concurrent corticosteroids Radiotherapy More than 4 weeks since prior radiotherapy Surgery More than 4 weeks since prior major surgery Other No other concurrent investigational agents