DISEASE CHARACTERISTICS: Histologically confirmed stage II or III multiple myeloma by bone marrow biopsy or aspiration Previously untreated with chemotherapy Melphalan and prednisone as only choice of standard treatment

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 1 year Hematopoietic: WBC at least 2,000/mm3 Absolute neutrophil count at least 1,000/mm3 Platelet count at least 50,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT or SGPT no greater than 3 times upper limit of normal (ULN) PT or PTT no greater than 1.2 times ULN Renal: Creatinine no greater than 2.0 mg/dL (if stage IIA or IIIA) Creatinine greater than 2.0 mg/dL (if stage IIB or IIIB) Cardiovascular: No myocardial infarction within the past 6 months No congestive heart failure Other: No other prior malignancy within the past 5 years except adequately treated basal cell or squamous cell cancer or carcinoma in situ of the cervix No other disease, psychiatric condition, or substance abuse that would preclude study No serious non-malignant disease, including uncontrolled infection or peptic ulcer disease HIV negative Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior transplantation or stem cell therapy No concurrent interferon therapy during initial melphalan and prednisone regimen Chemotherapy: See Disease Characteristics Concurrent other chemotherapy allowed if disease progression on study therapy Endocrine therapy: Not specified Radiotherapy: No more than 6 months since prior localized radiotherapy Concurrent localized radiotherapy allowed Surgery: Not specified Other: At least 30 days since prior investigational drug therapy Concurrent bisphosphonates for bone disease required No other concurrent enzyme preparation (including over the counter or nutraceutical preparations) No concurrent participation in other clinical study No concurrent anticoagulant therapy unless medically indicated