Long-term CR Multiple Myeloma Patients Show Cured or MGUS-like Minimal Residual Disease Pattern by Next Generation Flow

Background: In the era of novel agents, many multiple myeloma patients can achieve a complete remission, but most of them relapse, and minimal residual disease detection can play a crucial role. Next-generation flow (NGF) can detect monoclonal plasma cells with a sensitivity of 10-6. Little is known about long-term remission patients (> 2 years) and in particular, if more sensitive techniques such as NGF can still detect minimal disease in those patients. Objective: Aim of the study was to analyze patients with MM in response to NGF at > 2 years of sustained remission after several treatments. Methods: MRD was studied by NGF in bone marrow aspirates according to Euroflow Consortium indications. Results: 62 patients with sustained CR at >2 years were studied, MRD+ status was detected at a threshold cut-off of 10-6 in 32/62 (52%); 4/15 (27%) patients were MRD positive at >5 years of remission and they displayed a prevalence of normal vs abnormal monoclonal plasma cell immune-phenotype (MGUS-like). Conclusion: NGF is a powerful technique to detect MRD. Myeloma patients in prolonged sustained complete remission can show in high percentage an MRD negative status or MGUS like.