Iberdomide Alone or in Combination With Dexamethasone for the Treatment of Intermediate- or High-Risk Smoldering Multiple Myeloma

Inclusion Criteria: * Subject must have intermediate- or high risk smoldering multiple myeloma (SMM) as confirmed by at least one of the following factors either at screening or within 28 days of screening: * Bone marrow clonal plasma cells \>= 20% confirmed on either screening bone marrow biopsy or by outside pathology ≤5 years from initiation of study drug. * Abnormal serum free light chain ratio \> 20 by serum free light chain (FLC) assay * Serum monoclonal protein \>= 2 g/dL * Subject must have been diagnosed with SMM =\< 5 years from initiation of study drug * Both men and women of all races and ethnic groups are eligible for this study * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 (Karnofsky \>= 60%) is required for eligibility * Absolute neutrophil count (ANC) \>= 1500/uL * Hemoglobin (Hgb) \> 11 g/dL * Platelet count \>= 100,000 cells/mm\^3 and must be platelet and packed red blood cells (PRBC) transfusion independent with no granulocyte colony-stimulating factor (G-CSF) to ensure eligibility within 8 weeks of screening * Estimated creatinine clearance \>= 30 mL/min as defined by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) or Cockcroft-Gault * Total bilirubin \< 2 mg/dL except in subjects with congenital bilirubinemia such as Gilbert syndrome, in which case direct bilirubin =\< 2 times the institutional upper limit of normal is required * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \< 2.5 times the i…