Fluphenazine in Treating Patients With Refractory Advanced Multiple Myeloma

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed multiple myeloma * Advanced disease * Must be refractory to ≥ 2 different methods of standard treatment * Measurable disease, defined as serum paraprotein ≥ 1g/L or urine light chain ≥ 200 mg/24 hours * No brain involvement or leptomeningeal disease * No spinal cord compression unless the following criteria are met: * Patient has undergone prior surgery or radiotherapy * Neurological findings are ≤ grade 1 * Patient is off steroids for spinal cord edema or is on a stable regimen of ≤ 10 mg/day of prednisone or equivalent PATIENT CHARACTERISTICS: * ECOG performance status (PS) 0-2 (ECOG PS 3 allowed if related to skeletal lesions) * Life expectancy ≥ 12 weeks * Absolute granulocyte count ≥ 1,000/mm\^3\* * Platelet count ≥ 50,000/mm\^3\* * Hemoglobin ≥ 8.0 g/dL\* (no transfusion within the past 7 days) * AST and ALT ≤ 2.5 times upper limit of normal (ULN) * Bilirubin ≤ 2 times ULN * Creatinine clearance ≥ 30 mL/min * LVEF ≥ 40% * QTc \< 450 msec * No evidence of dysrhythmias on EKG * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No congestive heart failure * No angina pectoris * No cardiac arrhythmia * No uncontrolled hypertension, defined as systolic blood pressure (BP) \> 180 mm Hg and/or diastolic BP \> 105 mm Hg * No myocardial infarction within the past year * No active infection * No HIV, hepatitis B, or hepatitis C infection * No history of psychosis * No history of subcortical brain damage * No hypersensitivity to fluphenazine hydrochloride or other phenothiazines * No history of seizures or extrapyramidal symptoms * No other serious illness or medical condition * No other malignancy within the past 5 years except adequately treated nonmelanoma skin cancer or carcinoma in situ of the cervix NOTE: \*Patients with values outside of this range due to infiltration by myeloma may be allowed at the discretion of the investigator PRIOR CONCURRENT THERAPY: * See Disease Characteristics * Recovered from prior therapy * At least 21 days since prior chemotherapy, immunotherapy, or radiotherapy * At least 21 days since prior and no concurrent systemic steroids * Patients who have been taking chronically administered steroids for ≥ 1 month at a dose ≤ 10 mg/day of prednisone or equivalent are eligible * At least 28 days since prior investigational agents * At least 6 weeks since prior selective serotonin reuptake inhibitors (SSRIs) (a wash-out period equivalent to 5 times the terminal elimination half-life is required for tricyclic antidepressants or norepinephrine reuptake inhibitors) * No concurrent SSRIs, tricyclic antidepressants, or norepinephrine reuptake inhibitors * No concurrent dialysis therapy * No concurrent hematopoietic growth factors except epoetin alfa * Treatment with hematopoietic growth factors may be started during study if patient develops or has progressive cytopenia * No concurrent anticholinergics or other antipsychotics * No concurrent antiseizure drugs except Neurontin for treatment of neuropathy