There is little consensus about the optimal method for PBPC mobilization in patients with MM, although there is a growing recognition of suboptimal mobilization outcomes of certain subgroups of myeloma patients mobilized with G-CSF alone. Within this context, the adverse impact of prior lenalidomide therapy on PBPC mobilization is well documented; with up to 40% of MM patients treated with lenalidomide-based induction chemotherapies not collecting ≥2 x 106 CD34+ cells/kg when mobilized with G-CSF alone.