Leflunomide for the Treatment of High-Risk Smoldering Multiple Myeloma in African-American and European-American Patients

Inclusion Criteria: * All subjects must have the ability to understand and the willingness to sign a written informed consent * Patients must be age \>= 18 years * Patients must have a life expectancy of \> 24 months * Patients must exhibit an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 * Patients must identify as African-American OR European-American * Patients must have a diagnosis of high risk smoldering multiple myeloma, as defined below: * The presence of \>= 2 of the following risk factors: * Bone marrow plasma cell percentage (BMPC%) \> 20% * Serum M-protein \> 2 g/dL * Free light chain ratio (FLCr) \> 20 * A diagnosis of high-risk SMM must have been made within the last 3 years * At least 2 weeks from prior therapy to time of start of treatment. Prior therapy includes steroids (except prednisone or equivalent - up to 10 mg per day is allowed) * Platelet count \>= 50,000/uL. Platelet transfusions are not allowed within 14 days of platelet assessment * Absolute neutrophil count (ANC) \>= 1000/mm\^3 * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \< 2.0 x upper limit of normal (ULN) * Total bilirubin \< 1.5 x ULN * Calculated creatinine clearance (CrCl) \>= 30 mL/min per 24-hour urine collection or the Cockcroft-Gault formula * Negative serum or urine beta-human chorionic gonadotropin (HCG) test (female patient of childbearing potential only), to be performed locally within the screening period * Negative for…