Inclusion Criteria - Subjects must have undergone a prior ASCT for MM and have progressed within 365 days of stem cell infusion. Patients who underwent syngeneic transplant (i.e., transplant from an identical twin donor) rather than autologous transplant are eligible and syngeneic transplant will be considered equivalent to ASCT for the purposes of these inclusion/exclusion criteria. Progression will be defined according to IMWG criteria for progressive disease143 (Table 4).