Background:GEM-CESAR trial is a potentially curative strategy for high-risk smoldering multiple myeloma (HRsMM) patients (pts) in which the primary endpoint is the rate of minimal residual disease (MRD) negativity in the bone marrow (BM) assessed by next generation flow (NGF) after autologous stem cell transplantation (ASCT) and sustained 3 and 5 years afterwards. Here, we update the preliminary results presented at ASH2019 about the clinical value of quantitative immunoprecipitation mass spectrometry to assess treatment response in this group of patients.