Lenalidomide versus thalidomide based regimens as first-line therapy for patients with multiple myeloma.

Thalidomide (T) and lenalidomide (R) have been used as first-line therapy for previously untreated myeloma. However, direct head-to-head comparison between them is lacking. We performed an indirect meta-analysis to assess the treatment effects of lenalidomide- versus thalidomide-based regimens using common comparators. A comprehensive literature search was undertaken. The initial search yielded 1345 citations, of which 11 randomized controlled trials (RCTs) enrolling 4162 patients met the inclusion criteria. Indirect comparison of lenalidomide versus thalidomide maintenance after autologous stem cell transplant (ASCT) showed a progression-free survival (PFS) benefit (hazard ratio [HR] 0.75, 95% confidence interval [CI] [0.67, 0.85], p < 0.001) but no survival difference (HR 0.83, [0.63, 1.09], p = 0.19) when using observation/placebo as the common comparator. Similarly, the indirect comparison of melphalan-prednisone plus lenalidomide followed by lenalidomide maintenance (MPR-R) versus melphalan-prednisone-thalidomide induction followed by thalidomide maintenance (MPT-T) showed a statistically significant PFS advantage for MPR-R (HR 0.53, 95% CI [0.46, 0.60], p < 0.001), but no difference for overall survival (OS) (HR 0.97, [0.81, 1.17], p = 0.74). Additionally, the significant heterogeneity among pooled studies for the outcome of discontinuation rate due to treatment-related adverse events between MPT-T and MPR-R subgroups (p = 0.007) indicated that the discontinuation rate from thalidomide trials seems to be higher than that from lenalidomide trials. In conclusion, lenalidomide seems to be a more potent and less toxic agent than thalidomide in the treatment of patients with multiple myeloma. Further, a direct head-to-head trial comparing lenalidomide versus thalidomide is clearly warranted.