Relapse-free survival of complete responders after remission induction therapy according to MRD-negative/positive status. RFS according to attainment of MRD negativity for all patients (A), in the subgroup of patients with persistent positive MRD (B), and in those attaining a status of MRD negativity according to remission induction therapy (control group vs lenalidomide therapy group) (C). The unfavorable effect of MRD positivity is evident, but there is no apparent effect of lenalidomide treatment on outcome in patients attaining a status of MRD negativity or in patients with persistent MRD.