Lenalidomide and Low-Dose Dexamethasone in Patients With Previously Treated Multiple Myeloma and Kidney Dysfunction

Inclusion Criteria: * Diagnosed with previously treated multiple myeloma. * Measurable disease assessed by one of the following ≤21 days prior to registration: * Serum monoclonal protein ≥1 g by protein electrophoresis * Urine monoclonal protein \>200 mg on 24 hour electrophoresis * Serum immunoglobulin free light chain ≥10 mg/dL and abnormal serum immunoglobulin kappa to lambda free light chain ratio * Monoclonal bone marrow plasmacytosis ≥30% (evaluable disease) * If both serum and urine m-components are present, both must be followed in order to evaluate response. * All previous cancer therapy including chemotherapy, radiation, hormonal therapy and surgery, must be discontinued ≥2 weeks prior to registration. * Age ≥18 years. * Eastern Cooperative Oncology Group (ECOG) performance status 0-2. * Acceptable organ and marrow function ≤21 days prior to registration: * Absolute neutrophil count (ANC) ≥1000/mm³ * Platelet count ≥75,000/mm³ * Total bilirubin ≤2 mg/dL * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤3 x upper limit of normal * Renal impairment at baseline as measured by serum creatinine clearance (CrCl) ≤60 mL/min ≤21 days prior to registration. * Females of Childbearing Potential (FCBP) must have a negative pregnancy test within 10-14 days and again within 24 hours of starting Cycle 1 and must use an effective double-method contraception for ≥28 days prior to, during, and for ≥28 days after completion of study therapy. * Able to take required prophylactic anticoagulation. * Able to understand and willingness to sign a written informed consent. * Willing to provide blood samples for research purposes (Mayo Clinic sites only). * If previously received lenalidomide, demonstration of clinical response of any duration or stable disease with progression-free interval of ≥6 months from start of that therapy. Exclusion Criteria: * Concurrent use of other anti-cancer agents or treatments. Growth factors and bisphosphonates are allowed as medically indicated. Steroids may be used with an equivalency of up to 20 mg of Prednisone per day as long as the dose has not been adjusted upwards in past 2 weeks prior to study registration. * Uncontrolled intercurrent illness including, but not limited to, any of the following: * Ongoing or active infection requiring IV antibiotics * Symptomatic congestive heart failure * Unstable angina pectoris * Uncontrolled cardiac arrhythmia * Psychiatric illness/social situation that would limit compliance with study requirements. * Any of the following as this regimen may be harmful to a developing fetus or nursing child: * Pregnant women * Breast-feeding women * Men or women of childbearing potential or their sexual partners who are unwilling to employ adequate contraception. * HIV-positive patients on combination antiretroviral therapy. * Known hypersensitivity to thalidomide or other immunomodulatory drugs. * History of Stevens-Johnson syndrome characterized by a desquamating rash while taking thalidomide or similar drugs. * Other active malignancy except for non melanoma skin cancer or in situ cervical or breast cancer. * Concurrent radiation therapy, except for palliation of a single painful bone lesion or fracture.