Additional Study Information: This is research study for patients who have been newly diagnosed with Multiple Myeloma (MM). Their previous treatments have not been successful and their cancer is progressing. The purpose of this research study is to see if the study drug selinexor (KPT-330) has any effects against their cancer. This study combines the use of two drugs, selinexor (KPT-330) and dexmethasone, for treatment of Multiple Myeloma. The study drug selinexor (KPT-330) works by trapping "tumor suppressing proteins" within the cell and thus causing the cancer cells to die or stop growing.