Study of Pomalidomide, Cyclophosphamide, Dexamethasone in Relapsed/Refractory Multiple Myeloma

Inclusion Criteria: Disease related: * Patients must have a history of symptomatic multiple myeloma according to the IMWG criteria * Patients must have received at least two prior lines of therapy and also must be refractory to lenalidomide. * Patient has relapsed or relapsed/refractory MM. * Patients must currently have measurable disease, as defined as: 1. Serum M-protein ≥ 0.5 g/dL 2. Urine M-protein ≥ 200 mg/24 hours 3. Serum free light chain assay: involved FLC level ≥ 10 mg/dl provided serum FLC ratio is abnormal 4. If no monoclonal protein is detected, then \> 30% monoclonal bone marrow plasma cells Demographic: * Male or female adults ≥ 18 years old * Able to sign informed consent and to comply with the protocol * Life expectancy \> 12 weeks * ECOG performance status ≤ 2 * All study participants must be registered into the mandatory POMALYST REMS program, and be willing and able to comply with the requirements of the POMALYST REMS program. Laboratory * ANC ≥ 1000/µL * Platelets ≥ 50,000/µL (Patients with plasma cells 50% of bone marrow nucleated cells, and platelets ≥ 30,000/µL will be permitted regardless of the baseline ANC) * Cr \< 3 * AST ≤ 2.5 x ULN * ALT ≤ 2.5 x ULN * Serum Bilirubin ≤ 1.5 x ULN (except patients with Gilbert's syndrome who must have a total bilirubin of \<3 time ULN) Other * Females of childbearing potential must have a negative serum or urine pregnancy test with a sensitivity of at least 25 mIU/mL within 10 - 14 days prior to and again within 24 hours of starting pomalidomide and must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control at least 28 days before taking pomalidomide. Exclusion Criteria: * Previous treatment with pomalidomide * Patients who received chemotherapy or radiation therapy to 30% of marrow-bearing bone within ≤ 2 weeks or experimental agent/therapy within 4 weeks prior to starting study treatment; or who have not yet recovered from side effects of such therapies * Known hypersensitivity to thalidomide or lenalidomide * The development of erythema nodosum if characterized by a desquamating rash while taking thalidomide, lenalidomide or similar drugs * Other concurrent severe and/or uncontrolled medical conditions including abnormal laboratory values that could cause unacceptable safety risks or compromise compliance with the protocol * Patients for whom prophylactic anticoagulation therapy is not an option unless due to thrombocytopenia * Patients who received allogenic stem cell transplantation \< 12 months prior to entering the study or show evidence of active graft-versus-host disease that requires immunosuppressive therapy * Patients with existing peripheral neuropathy grade \> 2 * Patients with an active malignancy requiring treatment in the next 12 months (except for basal or squamous cell carcinoma, or in situ cancer of the cervix or breast, and asymptomatic prostate cancer) * Patients with known positivity for HIV or active hepatitis B or C * Corticosteroid therapies of \> 20 mg/day prednisone, \> 4 mg/day dexamethasone, \> 80 mg/day hydrocortisone, or equivalent. Oral, inhaled, or topical steroids are allowed during study as long as it does not exceed 80 mg/day hydrocortisone.