The purpose of this study is to compare the efficacy of the combination of Pomalidomide, Bortezomib and Dexamethasone to the combination of Bortezomib and Dexamethasone in patients with relapsed/refractory multiple myeloma. This study will also assess how safe the combination of Pomalidomide, Bortezomib and Dexamethasone is compared to the combination of Bortezomib and Dexamethasone