AUTHORS: J. Martinez-Lopez, A. Sureda, J. Blade, J. de la Rubia, E. Albizua, M.V. Mateos, R. Martinez, J.M. Ribera, J. Garcia-Larana, F. de Arriba, M.T. Hernandez, M.J. Terol, D. Carrera, J. Besalduch, F. Casado, L. Palomera, L. Escoda, S. Gardella, P. Ribas, P. Fernandez, P. Fernandez-Abellan, B. Hernandez, J. San Miguel & J.J. Lahuerta
from the Grupo Espanol de Mieloma (GEM)
EBMT Myeloma Subcomittee redefined response criteria for MM treatment in 1998. In summary, negative immunofixation (IF) was established as a requisite for CR. The retrospective study of Spanish Registry of MM Transplantation, which was designed to validate the prognostic significance of CR defined by EBMT criteria, concluded that patients with negative IF constituted a subgroup with better prognosis than those with negative electrophoresis but positive IF. GEM-2000 protocol included, among its objectives, a prospective confirmation of the previously referred results. Patients and Methods: 1088 patients were included in this clinical trial, GEM-2000 protocol. All patients included in this protocol were treated with 6 alternative chemotherapy cycles (using VBMCP/VBAD), and either BUMEL or MEL200 as conditioning regimen. A second transplantation was performed if patients did not reach complete remission. Complete remission (CR) was defined when IF results were negative; when EEF(-) but IF(+), the response was called Near Complete Remission (nCR). Other response categories were also evaluated: Partial Response (PR); Minor Response (MR); Stable Disease (SD) and Progression. Response was evaluated after chemotherapy, 1st or 2nd Stem Cell Transplantation in 740 patients (n? of cases per response category at time of maximum response: CR=295 (39,9%); nCR= 129 (17,4%); PR=239 (32,3%); MR=23 (3,1%); SD=6 (0,8%); Progression= 49 (6,6%). MR and SD categories were not included in subsequent analysis due to the low number of patients. Results (table): At median follow-up of 50,4 months, median was not reach and 67,5% of patients are still alive at 5 y. EFS and PFS were significantly better in the group of patients in CR than in group of ECR, and this was also superior to PR. Patients in Progression had a significantly worse outcome as compared to the rest of the patients(p<0,000). Multivariate analysis confirmed the independent prognostic impact of response categorization (SLE OR for CR was125 p=0.000, for ECR OR was 8 p=0,125, for RP OR was 4,1 p=0,02; model p<0.000; X2 91,43). Conclusion: This large prospective study shows that response after transplant is a major prognostic factor that could be used a surrogate marker for predicting disease outcome. Patients with CR IF- have longer survival than patients with nCR, and these longer than PR patients.