Lenalidomide after stem-cell transplantation for multiple myeloma: a meta-analysis of randomized controlled trials.

The efficacy and safety of lenalidomide maintenance therapy after ASCT in patients with MM has been in question. In order to address the issue, we conducted a meta-analysis of two randomized double-blind placebo-controlled studies encompassing 1074 patients treated with lenalidomide or placebo maintenance therapy after ASCT. The predominant clinical outcomes of interest were overall survival (OS), progression-free survival (PFS), and adverse events. There was a marked benefit in PFS with lenalidomide (Odds Ratio [OR] = 2.5, 95% confidence interval [CI] = 1.93 to 3.24). There was statistically non-significant tendency toward benefit in OS with lenalidomide (OR = 1.21, 95% CI = 0.65 to 2.24). For adverse events, more patients in lenalidomide treatment arm experienced neutropenia (OR = 4.88, 95% CI = 3.67 to 6.50), infection (OR = 2.82, 95% CI = 1.67 to 4.73), hematologic cancers (OR = 3.31, 95% CI = 1.30 to 8.41), and solid tumors (OR = 2.24, 95% CI = 1.01 to 4.98). No significant differences were seen with deep vein thrombosis (OR = 2.15, 95% CI = 0.92 to 5.06), peripheral neuropathy (OR = 1.50, 95% CI = 0.53 to 4.25), thrombocytopenia (OR = 1.05, 95% CI = 0.12 to 9.54), and anemia (OR = 1.36, 95% CI = 0.02 to 83.86). Based on these results, we conclude that lenalidomide maintenance therapy for patients with MM after ASCT was effective in the improvement of PFS. However, treatment-related adverse events must be close monitored. Although there was a trend for increased OS with lenalidomide, there was no statistically significant difference in OS between lenalidomide maintenance therapy arm and placebo maintenance therapy arm. Therefore, longer follow-up and additional high quality RCTs were needed to evaluate the effects of lenalidomide maintenance on OS.