Interpretation of randomized trials of lenalidomide. Regulatory trials that showed the value of lenalidomide as a new active agent in myeloma used PFS as the primary endpoint. (A) In this instance, improvement in PFS over the control arm can be reasonably interpreted as proving the clinical benefit of the given drug because patients in the control group will not have access to lenalidomide in real life in the absence of regulatory approval. (B) In contrast, in trials in which the early use of lenalidomide as maintenance therapy was tested, an improvement in PFS may or may not translate into clinical benefit because patients in the control arm do have access to lenalidomide at the time of relapse in real life.