Interferon Maintenance in Advanced Multiple Myeloma After Using High-Dose Melphalan as Myeloablative Chemotherapy: A Pilot Study

OBJECTIVES: I. Determine the effectiveness of interferon alfa-2b maintenance following high dose melphalan chemotherapy for patients with advanced multiple myeloma. II. Determine the response rate to high dose dexamethasone therapy using sequential noncrossresistant chemotherapies for patients with advanced multiple myeloma. OUTLINE: Patients receive high dose dexamethasone on days 1-4, 9-12, and 17-20, followed by 4 weeks rest. Cyclophosphamide (CTX) is administered intravenously in combination with mesna following dexamethasone therapy. Sargramostim (GM-CSF) is initiated subcutaneously 1 day later and is continued for 10 days to support stem cell collections, which begin 10-14 days after CTX induction. Following 4 weeks of rest, melphalan (L-PAM) is administered over 1 hour. Stem cell rescue is begun 48 hours after L-PAM therapy. Three to 4 months after the first L-PAM course, a second L-PAM and stem cell rescue is undertaken. Interferon alfa-2b (IFN-A) maintenance is administered 3 times per week following bone marrow recovery from the first or second L-PAM courses. Patients achieving complete remission following the first course of L-PAM may proceed directly to IFN-A maintenance. Patients achieving greater than grade 3 nonhematologic toxicity or not achieving an absolute neutrophil count of greater than 1,000/mm3 by day 21 posttransplant are not eligible for dose escalation. PROJECTED ACCRUAL: A minimum of 30 patients will be enrolled.