O6-benzylguanine And Carmustine in Treating Patients With Multiple Myeloma

DISEASE CHARACTERISTICS: Histologically confirmed progressive multiple myeloma, meeting 1 of the following criteria: Previously untreated Primary refractory Relapsing disease Major criteria: Plasmacytomas on tissue biopsy Bone marrow plasmacytosis with greater than 30% plasma cells Monoclonal globulin spike on serum electrophoresis Greater than 3.5 g/dL for G peaks or greater than 2.0 g for A peaks Greater than 1.0 g/24 hours of kappa or lambda light chain excretion on urine electrophoresis in the absence of amyloidosis Minor criteria: 10%-30% bone marrow plasmacytosis (criterion A) Presence of monoclonal globulin spike but less than the levels under major criteria (criterion B) Lytic bone lesions (criterion C) IgM less than 50 mg/dL, IgA less than 100 mg/dL, or IgG less than 600 mg/dL (criterion D) Must meet one of the following: A minimum of 1 major criterion and 1 minor criterion 3 minor criteria, including criteria A and B PATIENT CHARACTERISTICS: Age: Not specified Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: WBC greater than 3,000/mm^3 Platelet count greater than 100,000/mm^3 Absolute neutrophil count greater than 1,500/mm^3 Hemoglobin greater than 9 g/dL (transfusions allowed) Hepatic: Bilirubin less than 1.5 mg/dL AST/ALT less than 2 times normal Renal: Creatinine no greater than 2.0 mg/dL OR Creatinine clearance greater than 60 mL/min Calcium less than 14 mg/dL Pulmonary: No prior or concurrent active, symptomatic respiratory disease Corrected DLCO at least 60% predicted Other: Controlled diabetes mellitus allowed Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 2 months after study participation PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No more than 1 prior chemotherapy regimen containing an alkylating agent for multiple myeloma At least 4 weeks since prior chemotherapy Endocrine therapy: Prior corticosteroids for multiple myeloma allowed Radiotherapy: No prior pelvic radiotherapy or radiotherapy to more than 25% of bone marrow Surgery: Not specified