Dexamethasone With or Without Oblimersen in Treating Patients With Relapsed or Refractory Multiple Myeloma

DISEASE CHARACTERISTICS: NOTE: This trial is being conducted at many institutions throughout the country. Please contact Genta for a site near you. * Progressive multiple myeloma defined by one of the following: * Primary resistance or progressive disease after achieving less than a partial response after at least 2 courses of combination chemotherapy (that included at least 1 myelosuppressive drug) within the past 3 months * Relapsed or progressive disease after at least a partial response to prior therapy * Progressive disease after high-dose chemotherapy and autologous stem cell transplantation * Progressive disease defined by at least 1 of the following: * Increase in serum M-protein by at least 50% or at least 2 g/dL above the lowest remission or baseline level * Increase in urinary M-protein by at least 50% or at least 2 g/24 hours above lowest remission or baseline level * Appearance of new lytic bone lesions or at least 50% increase in size of an existing bone lesion * Quantifiable serum and/or urine paraprotein * Bone marrow plasmacytosis at least 5% of total nucleated cells * Measurable disease * Serum M-protein level at least 1.0 g/dL OR * Urinary M-protein excretion at least 200 mg/24 hours PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * ECOG 0-3 Life expectancy: * Not specified Hematopoietic: * Absolute neutrophil count at least 1,000/mm3 * Platelet count at least 50,000/mm3 * No bleeding or coagulation disorder Hepatic: * Bilirubin no greater than 1.5 times upper limit of normal (ULN) * AST no greater than 2.5 times ULN * PT and PTT no greater than 1.5 times ULN * No history of chronic hepatitis or cirrhosis Renal: * Creatinine no greater than 1.5 mg/dL Cardiovascular: * No active symptoms of coronary artery disease (e.g., uncontrolled arrhythmias or recurrent chest pain despite prophylactic medication) * No New York Heart Association class III or IV heart disease * No uncontrolled congestive heart failure * No grade 2 or greater cardiovascular signs or symptoms within the past 4 weeks Other: * HIV negative * No active peptic ulcer disease * No uncontrolled seizure disorder * No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix * No active uncontrolled infection * No active autoimmune disease * No hypersensitivity to phosphorothioate-containing oligonucleotides or to dexamethasone * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * See Disease Characteristics * At least 3 weeks since prior immunotherapy * At least 72 hours since prior thalidomide * Concurrent epoetin alfa allowed Chemotherapy: * See Disease Characteristics * At least 3 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosourea) Endocrine therapy: * At least 3 weeks since prior corticosteroids * No concurrent chronic corticosteroids Radiotherapy: * At least 14 days since prior radiotherapy except limited radiotherapy to a single bone lesion Surgery: * At least 3 weeks since prior major surgery * No prior organ allograft Other: * At least 4 weeks since other prior investigational therapy * No more than 6 prior therapies for myeloma * No concurrent immunosuppressive therapy