Combination Chemotherapy With or Without High Dose Cyclophosphamide and Recombinant Interferon Alfa-2b in Treating Patients With Previously Untreated Stage I-III Multiple Myeloma

PRIMARY OBJECTIVES: I. To compare response rate, time to response, duration of response, toxicity, and survival in the two regimens (vincristine sulfate, carmustine, melphalan, cyclophosphamide, prednisone \[VBMCP\] vs. VBMCP alternating with high-dose cyclophosphamide and then with recombinant interferon alfa-2b \[r alpha2b-IFN\]) in patients with previously untreated multiple myeloma. II. To determine the value of the ancillary laboratory studies to predict response and survival. OUTLINE: INDUCTION PHASE: Patients receive VBMCP comprising vincristine sulfate intravenously (IV) on day 1, carmustine IV on day 1, melphalan orally (PO) on days 1-4, cyclophosphamide IV on day 1, and prednisone PO on days 1-7. Treatment repeats every 35 days for 2 courses in the absence of disease progression or unacceptable toxicity. CONSOLIDATION PHASE: Patients are randomized to 1 of 2 treatment arms. ARM A: Patients receive VBMCP as in the induction phase. Courses repeat every 35 days in the absence of disease progression or unacceptable toxicity. ARM B: Patients receive vincristine sulfate, carmustine, and melphalan as in the induction phase, high-dose cyclophosphamide IV on days 1-4 and prednisone PO on days 1-4 during courses 3 and 5. Patients receive VBMCP as in the induction phase during even numbered courses. Patients receive recombinant interferon alfa-2b subcutaneously (SC) on days 1, 3, 5, 8, 10, 12, 15, 17, 19, and 22 during odd courses beginning course 7. Treatment repeats every 35 days for courses 3-5, every 21 days for even courses beginning course 6, and every 22 days for odd courses beginning course 7 in the absence of disease progression or unacceptable toxicity. In both arms, treatment continues for up to 2 years. After completion of study treatment, patients are followed up for 1 year.