Background: Treatment with lenalidomide and dexamethasone has proven efficacy in two large randomized trials (MM-009 and MM-010) leading to a time to progression (TTP) of 17.1 months for patients with only one prior therapy and a TTP of 10.6 months for 2 and more prior therapies, respectively [1-3]. Continuous treatment with lenalidomide and dexamethasone until disease progression is therefore considered a standard therapy for second line treatment in multiple myeloma patients. However, only a relatively low rate of high quality response (CR, complete response and VGPR, very good partial response) is achieved. High quality responses are associated with with improved progression-free survival and overall survival [4].