DISEASE CHARACTERISTICS:

• Diagnosis of multiple myeloma

  • Relapsed or refractory disease

• Measurable or evaluable disease as defined by at least 1 of the following:

  • Serum monoclonal protein ≥ 1.0 g by protein electrophoresis
  • Monoclonal protein ≥ 200 mg by 24-hour urine electrophoresis
  • Serum immunoglobulin free light chain ≥ 10 mg/dL AND abnormal serum immunoglobulin kappa to lambda free light chain ratio
  • Monoclonal bone marrow plasmacytosis ≥ 30% (evaluable disease)

• Previously treated disease

  • No limit to prior therapy provided there is adequate residual organ function
• Must have undergone hematopoietic stem cell collection (for transplant candidates) OR not considered to be a hematopoietic stem cell transplant candidate

PATIENT CHARACTERISTICS:

• ECOG performance status (PS) 0-2 (ECOG PS of 3 allowed if secondary only to pain)
• Platelet count ≥ 75,000/mm^3
• Hemoglobin ≥ 8.0 g/dL (transfusion allowed)
• ANC ≥ 1,000/mm^3
• Creatinine ≤ 3 mg/dL
• Calcium ≤ 15 mg/dL
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 4 weeks after completion of study therapy
• No impending long bone fracture
• No other active malignancy except nonmelanoma skin cancer, carcinoma in situ of the cervix, or breast cancer
• No uncontrolled infection
• No known hypersensitivity to any of the components of study drugs
• No other co-morbidity that would preclude study participation

PRIOR CONCURRENT THERAPY:

• Recovered from prior surgery, radiotherapy, or other antineoplastic therapy
• No prior samarium Sm 153 lexidronam pentasodium or strontium chloride Sr 89
• At least 3 weeks since prior myelosuppressive agents
• At least 2 weeks since prior nonmyelosuppressive agents (e.g., thalidomide)

• At least 2 weeks since prior and no concurrent high-dose corticosteroids

  • Chronic steroids (maximum dose of 20 mg/day prednisone or equivalent) allowed for disorders other than myeloma (i.e., adrenal insufficiency or rheumatoid arthritis)
• At least 30 days since prior and no other concurrent investigational therapy
• No concurrent external beam radiotherapy
• No concurrent cytotoxic chemotherapy

• No other concurrent systemic antineoplastic therapy including, but not limited to, any of the following:

  • Immunotherapy
  • Hormonal therapy
  • Monoclonal antibody therapy