HIGH-DOSE SEQUENTIAL CHEMORADIOTHERAPY, A WIDELY APPLICABLE REGIMEN, CONFERS SURVIVAL BENEFIT TO PATIENTS WITH HIGH-RISK MULTIPLE-MYELOMA

Purpose: To assess the toxicity, efficacy, and applicability of high-dose therapy with bone marrow and/or peripheral-blood autotransplantation in high- risk, previously untreated patients with multiple myeloma. Patients and Methods: Thirteen consecutive patients with high-labeling index (LI) multiple myeloma received a novel high-dose sequential (HDS) regimen consisting in the high-dose administration of cyclophosphamide (7 g/m2) followed by vincristine (1.4 mg/m2) plus methotrexate (8 g/m2 with leucovorin rescue), etoposide (2 g/m2) and, finally, total-body irradiation (TBI; 10 Gy) plus melphalan (120 mg/m2) with autografting of peripheral-blood hematopoietic progenitor cells. Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF; 5 μg/kg/d) was continuously infused after cyclophosphamide and etoposide both to accelerate hematopoietic recovery and to expand/mobilize the hematopoietic progenitor-cell pool. Results: Among 13 patients, 12 completed the program; 10 (or 77%) achieved a complete response and five are alive and disease-free after a median follow-up duration of 36 months (range, 24 to 52). The durations of both freedom from progression (FFP; median, 38 months) and overall survival (OS; median, 41 months) were significantly superior in the 13 HDS-treated patients as compared with 19 well-matched historical controls. Conclusion: HDS emerges as a highly effective, well-tolerated, and widely accessible regimen capable of imparting a survival benefit to patients with high-LI multiple myeloma. Larger studies using this or similar programs in standard-risk myeloma are clearly warranted.