Lenalidomide with dexamethasone to multiple myeloma patients relapsing from bortezomib-based induction therapies: A prospective, observational study.

Lenalidomide with dexamethasone (Len/Dex) is considered to be an effective and well-tolerated regimen to treat multiple myeloma (MM) patients relapsing after bortezomib induction therapy. With the increase in novel agents targeting refractory and relapsed MM, the identification of clinical or laboratory variables that can predict the appropriate candidates of Len/Dex is essential. To address this question, we prospectively assessed 38 adult MM patients who received bortezomib-based induction therapy and were administered Len/Dex for their first relapse. These 38 patients were stratified into the symptomatic relapse group (n = 10) and biological relapse group (n = 28) according to the disease status when Len/Dex was initiated. The overall response rate in the symptomatic group and biological relapse group was 70.0% (7/10) and 60.7% (17/28), respectively (P = 0.964). These two groups harbored a comparable median Len/Dex treatment duration (139 vs. 225 days; P = 0.876) and progression-free survival 2 (PFS2) (501 vs. 1289 days; P = 0.410). Multivariate analyses failed to show that treating biological relapse (hazard ratio [HR]: 1.29; 95% confidence interval [CI]: 0.43-3.88; P = 0.648), PFS with bortezomib-based induction therapies ≥18 months (HR: 1.79; 95% CI: 0.64-5.01; P = 0.266), autologous hematopoietic stem cell transplantation (HR: 2.18; 95% CI: 0.56-8.55; P = 0.262), and high-risk cytogenetics (HR: 0.85; 95% CI: 0.18-3.93; P = 0.835) were attributed to depth of Len/Dex treatment. In conclusion, whether MM patients treated by Len/Dex for biological relapse would have a better outcome than those prescribed for symptomatic relapse remains inconclusive. Treating significant biological relapse and symptomatic relapse remains the current consensus.