High-dose cyclophosphamide. An effective treatment for advanced refractory multiple myeloma.

The Eastern Cooperative Oncology Group evaluated cyclophosphamide 600 mg/m2 intravenously daily X 4 (total dose each cycle 2400 mg/m2) as an aggressive approach to the treatment of patients with advanced multiple myeloma. The overall objective response rate is 43%. This includes a 38% response rate for all previously treated patients and a 29% response rate for patients refractory to prior therapy with cyclophosphamide. The objective response duration was 3 months and the survival of responding patients 9 months. A subjective response rate of 63% was observed, characterized by effective pain relief and improved performance. Sixty-nine percent of patients experienced leukocyte cell nadirs less than 500/mm2 with a mean time to marrow recovery of 17 days. Thrombocytopenia was less severe but required platelet transfusion in 43% of patients. Bone marrow toxicity was encountered in all patients, and death in aplasia is a significant risk. Strict adherence to entry criteria, and a systematic plan for hospitalization for antibiotic and blood component support is required for treatment with this regimen.