Study of Pomalidomide, Oral Dexamethasone and Very Low-dose Cyclophosphamide in Patients With Refractory Multiple Myeloma Who Have Received Lenalidomide and Bortezomib

Inclusion Criteria: * Patient over 18 years of age and who meets criteria 2 and / or 3. * Patient diagnosed with symptomatic Multiple Myeloma according to standard criteria. * Patients with symptomatic multiple myeloma in relapse / refractory after having received treatment with at least two cycles that include Bortezomib and with at least two cycles that include Lenalidomide, whether combined in the same therapeutic scheme or as part of different chemotherapy schemes. * Patients with MM with measurable disease, defined as the presence of monoclonal component of at least 0.5 g / dL in serum or at least 0.2 g / d in urine, or in those without measurable disease the presence of altered light chain radius at the time of entry into the study. * Patients with good general condition defined as ECOG ≤ 2. * The patient must understand the written informed consent and sign it of his own accord. * The patient must be able to meet all scheduled visits and other requirements. * Laboratory Criteria: Patients must present the following counts:Absolute neutrophils: ≥1000 / μL, Platelet Count: ≥50,000 / μL, Hemoglobin:\> 8 gr / dL, Total bilirubin: \<2 x upper limit of normal, AST and ALT: \<3 x Upper limit of normal, Serum potassium: within the limits of normality. * Women of childbearing age should have a negative pregnancy test. * The male patient included in the trial must commit to always use a latex condom during any sexual contact with women of childbearing age, even if they have undergone a successful vasectomy. Exclusion Criteria: * Any concomitant disease, laboratory alteration or psychiatric disorder that may presuppose the subject's inability to sign the IC. * PS\> 3 according to the ECOG scale. * Previous history of non-hematologic malignancies, unless the patient has been free of the disease for ≥ 5 years. Exceptions include the following: Basal cell carcinoma of the skin, Squamous cell carcinoma of the skin, Carcinoma in situ of the cervix, Carcinoma in situ of the breast. * Patients who are unable or unwilling to undergo antithrombotic therapy. * Known positive serology for human immunodeficiency virus HIV or active infectious hepatitis, type B, or C. * Depressed heart function, or clinically significant heart disease * Severe hypercalcemia * Major surgical interventions within 15 days prior to inclusion or not having recovered from their side effects. * Any serious medical condition, including laboratory alterations that cause the patient to take an unacceptable risk if participating in this study or that may interfere with the interpretation of the study data. * Patients treated with any investigational drug in the previous 28 days. * Any severe medical condition, abnormality in laboratory tests or any psychiatric illness that prevents the signing of written consent. * Pregnant or breastfeeding women. * Known hypersensitivity to drugs or compounds of biological or chemical composition similar to those of the study. * Plasma Cell Leukemia