Lenalidomide, and Dexamethasone With or Without Daratumumab in Treating Patients With High-Risk Smoldering Myeloma

Inclusion Criteria: * Patients must be diagnosed with asymptomatic high-risk smoldering multiple myeloma (SMM) within the past 12 months. High-risk is defined by the presence of 2 or more of the following factors: * Abnormal serum free light chain ratio of involved to uninvolved \>20, but less than 100 if the involved FLC is \>= 10 mg/dL by serum free light chain (FLC) assay * Serum M-protein level \>= 2 gm/dL * Presence of t(4;14) or del 17p, del 13q or 1q gain by conventional cytogenetics or fluorescence in situ hybridization (FISH) studies. * \>20% plasma cells on biopsy or aspirate * Bone marrow aspirate and/or biopsy is required to be performed within 42 days prior to randomization and must demonstrate 10-59% clonal plasma cells. * \>= 1 g/dL on serum protein electrophoresis (within 28 days prior to randomization). * \>= 200 mg of monoclonal protein on a 24 hour urine protein electrophoresis (within 28 days prior to randomization). * NOTE: In the rare situation where the serum protein electrophoresis (SPEP) is felt to be unreliable, then quantitative immunoglobulin levels on nephelometry or turbidometry can be accepted. * SPEP, urine protein electrophoresis (UPEP), and serum FLC are required to be performed within 28 days prior to randomization. * NOTE: UPEP (on a 24-hour collection) is required; no substitute method is acceptable. Urine must be followed monthly if the baseline urine M-spike is \>= 200 mg/24 hour (hr), and urine in addition to serum must …