Lenalidomide as salvage therapy after allo-SCT for multiple myeloma is effective and leads to an increase of activated NK (NKp44+) and T (HLA-DR+) cells

We investigated efficacy and toxicity of lenalidomide in 24 heavily pretreated myeloma patients with a median age of 59 years (range: 37-70) and relapse after allo-SCT. Lenalidomide was given at a dose of 15 mg (n = 4), or 25 mg (n 20), orally once daily on day 1 to day 1 every 28 days, with (n 20) or without (n 4) DHAP. The median number of lenalidomide cycles was five (range: 2-17). Major side effects were leukopenia (grade 4: 4%, grade 3: 21% and grade 2: 17%) and thrombocytopenia (grade 3: 17% and grade 2: 29%); infectious complications were observed in 50%. Non-hematological toxicity consisted of muscle cramps (n 9), fatigue (n 5) and constipation (n 2). Mild grade I-II GVHD was seen in three patients. Response was achieved in 66%: CR in 8%, VGPR in 8%, PR in 50% and SD in 13%. The median time to progression was 9.7 months (95% confidence interval (CI): 7.5-11.9), and median OS was 19.9 months (95% CI: 17.3-22.5). Immunomonitoring after lenalidomide showed significant increase of activated NK (NKp44(+)) and T (HLA-DR+) cells, as well as regulatory T cells (CD4(+), CD25(+), CD127(lo)), supporting an immunomodulating anti-myeloma effect of lenalidomide. Bone Marrow Transplantation (2010) 45, 349-353; doi:10.1038/bmt.2009.155; published online 6 July 2009