Complete response in multiple myeloma: Clinical trial E9486, an Eastern Cooperative Oncology Group study not involving stem cell transplantation

BACKGROUND. The importance of obtaining a complete response (CR) in multiple myeloma (MM) treated with chemotherapy is unclear. METHODS. The Eastern Cooperative Oncology Group evaluated 653 previously untreated patients with active MM randomized to vincristine, carmustine (BCNU), melphalan, cyclophosphamide, and prednisone (VBMCP), to VBMCP and recombinant interferon alfa-2 (INFα-2), or to VBMCP and high-dose cyclophosphamide. RESULTS. Objective response was achieved in 420 (67%) of the 628 eligible patients, and 85 (14%) achieved a CR. Patients receiving VBMCP and recombinant INFα-2 had a significantly higher CR (18%) than those receiving VBMCP alone (10%) (P = .02). The CR rate for VBMCP and high-dose cyclophosphamide was 12%. Median duration of survival was 3.5 years for all eligible patients, and the estimated 5-year survival rate was 31%. The median duration of survival from the date of objective response was 5.1 years for those who achieved a CR and 3.3 years for those with a partial response (P < .0001). The median postresponse survival was 6.6 years in the 21 patients in CR with nonclonal disease and 4.4 years in the 11 patients in CR who had persistent clonal disease. All patients with negative immunofixation results and nonclonal plasma cells in whom polymerase chain reaction was performed had a positive result (presence of tumor DNA). CONCLUSION. Patients in whom a CR was achieved had a longer survival than those who had a partial response.