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