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The achievement of complete response (CR) after high-dose therapy/autologous stem cell transplantation (HDT/ASCT) is a surrogate for prolonged survival in multiple myeloma; however, patients who lose their CR status within 1 year of HDT/ASCT (unsustained CR) have poor prognosis. Thus, the identification of these patients is highly relevant. Here, we investigate which prognostic markers can predict unsustained CR in a series of 241 patients in CR at day ؉100 after HDT/ASCT who were enrolled in the Spanish GEM2000 (n ‫؍‬ 140) and GEM2005 < 65y (n ‫؍‬ 101) trials. Twenty-nine (12%) of the 241 patients showed unsustained CR and a dismal outcome (median overall survival 39 months). The presence of baseline high-risk cytogenetics by FISH (hazard ratio 17.3; P ‫؍‬ .002) and persistent minimal residual disease by multiparameter flow cytometry at day ؉100 after HDT/ASCT (hazard ratio 8.0; P ‫؍‬ .005) were the only independent factors that predicted unsustained CR. Thus, these 2 parameters may help to identify patients in CR at risk of early progression after HDT/ASCT in whom novel treatments should be investigated. (Blood. 2012;119(3):687-691) IntroductionThe incorporation of high-dose therapy/autologous stem cell transplantation (HDT/ASCT) and novel agents in the treatment of young patients with multiple myeloma (MM) has markedly improved the achievement of complete response (CR). 1,2 There are now extensive data in the setting of HDT/ASCT showing that achievement of CR is associated with prolonged survival. 3 Although this is well accepted, the long-term clinical outcome of MM patients who achieve CR is still heterogeneous, 4 and 2 important observations must be made: (1) some patients who revert to a monoclonal gammopathy of undetermined significance (MGUS) stage after therapy experience similar prolonged survival as patients in CR 5 ; and (2) a small fraction of patients unexpectedly lose their CR status during the first year after HDT/ASCT and experience a dismal survival rate. 6,7 In fact, survival of patients with unsustained CR is even poorer than for those not achieving CR. 6,7 Herein, we sought to identify prognostic markers predictive of unsustained CR after HDT/ASCT. MethodsThe study included 241 MM patients diagnosed according to International Myeloma Working Group criteria. 8 Patients were included in 2 consecutive PETHEMA/GEM (Programa para el Estudio de la Terapéutica en Hemopatías Malignas/Grupo Español de Mieloma) trials: GEM2000 (VBMCP [vincristine, carmustine, melphalan, cyclophosphamide, and prednisone]/VBAD [vincristine, carmustine, doxorubicin, and dexamethasone] followed by HDT/ASCT and 2 years of maintenance with interferon and prednisone; n ϭ 140) and GEM2005 Ͻ 65y (randomized induction with the same chemotherapy plus bortezomib in the last 2 cycles or thalidomide/dexamethasone or bortezomib/thalidomide/dexamethasone followed by HDT/ASCT, and 3 years of maintenance with interferon-␣2b or thalidomide or thalidomide/bortezomib; n ϭ 101). All case subjects were in CR at day ϩ100 after HDT/ASCT, def...

Achieving an IR translates into superior PFS and TTP compared with conventional CR or stringent CR. These techniques provide complementary information and thus, an effort should be made to refine response criteria in MM.