Highest treatment efficacy in patients with refractory myeloma may be achieved with regimens combining novel agents and alkylating agents. However, in applying this approach the patients are at substantial risks of a critical myelosuppression. Pomalidomide demonstrates significant activity in combination with Dexamethasone in relapsed or refractory multiple myeloma. This trial is an attempt to further improve the efficacy of Pomalidomide/Dexamethasone as well as to balance efficacy and toxicity. Integration of Cyclophosphamide in the treatment in case of suboptimal response or first evidence of progressive disease has the aim to significantly increase duration of treatment that should have a positive impact on PFS. It is furthermore an attempt to optimize the potential of Pomalidomide in the antimyeloma efficacy. Based on the recent findings, that myeloma is a disease with a wide clonal heterogeneity, combination treatment in case of suboptimal myeloma control might lead to a more effective suppression especially of aggressive subclones and might reduce early resistance. In addition, with the goal of keeping the individual patient as long as possible under an effective IMiD treatment, the potential of the drug might be optimized according to the current view of maintenance treatment resulting ideally in an outgrowth of indolent clones in the bone marrow niche.