**8. Immunomodulatory drugs (IMiDs)**

Meta-analysis of randomized clinical studies of phase III with thalidomide as maintenance therapy confirms the benefits of use after autologous transplantation. Statistically significant increase of PFS in six studies and overall survival prolongation in three studies were noted. On the other hand, only one third of patients tolerated thalidomide maintenance therapy for more than a year. At this point, when there are less toxic drugs available for maintenance therapy, thalidomide is recommended as a part of short-term intensive consolidation therapies in [29,28,30].

Lenalidomide was tested in two independent randomized clinical trials of phase III as maintenance treatment after autologous transplantation. Both these trials, CALGB 100104 and IFM 2005-02, demonstrated benefit from lenalidomide compared to placebo, which showed a major decrease in risk of progression by 60% in [21] and an improvement of three-year PFS in the group with lenalidomide (61% vs. 34%) in [20]. Based on new analyses (follow-up of 28 months), there was a statistically significant improvement in overall survival in Len/Dex treated groups of patients in comparison to the placebo treated group of patients, regardless of short follow-ups in [21]. Its role in maintenance therapy is highlighted by improved results when RMP-R treatment is used with maintenance therapy compared to RMP without main‐ tenance therapy in a study of seniors MM-015 in [31]. RMP-R treatment ensured one of the longest median of PFS (31 months). Maintenance therapy of lenalidomide was generally well tolerated with no signs of cumulative toxicity as in the case of thalidomide. Although the occurrence of secondary malignancies after lenalidomide treatment was increased, the risk of disease progression or death by MM overcame this risk in [5]. Despite superb results of maintenance therapy by lenalidomide, it is not yet approved for maintenance therapy till the end of the year 2012 mainly due to safety reasons, although long-term results are also limited.
