Bortezomib plus dexamethasone vs thalidomide plus dexamethasone for relapsed or refractory multiple myeloma

A randomized phase II selection design study (JCOG0904) was carried out to evaluate the more promising regimen between bortezomib (Bor) plus dexamethasone (Dex; BD) and thalidomide (Thal) plus Dex (TD) in Bor and Thal-naïve patients with relapsed or refractory multiple myeloma (RRMM). Patients ≥20 and <80 years old with a documented diagnosis of symptomatic multiple myeloma (MM) who received one or more prior therapies were randomized to receive BD (Bor 1.3 mg/m² ) or TD (Thal 200 mg/d). In both arms, 8 cycles of induction (3-week cycle) were followed by maintenance phase (5-week cycle) until disease progression, unacceptable toxicity, or patient refusal. The primary end-point was 1-year progression-free survival (PFS). Forty-four patients were randomized and assigned to receive BD and TD (n = 22, each group). At a median follow-up of 34.3 months, the 1-year PFS in the BD and TD arms were 45.5% (95% confidence interval (CI), 24.4%-64.3%) and 31.8% (95% CI, 14.2%-51.1%), respectively, and the overall response rates were 77.3% and 40.9%, respectively. The 3-year overall survival (OS) was 70.0% (95% CI, 44.9%-85.4%) in the BD, and 48.8% (95% CI, 25.1%-69.0%) in the TD arm. Among grade 3/4 adverse events, thrombocytopenia (54.5% vs 0.0%) and sensory peripheral neuropathy (22.7% vs 9.1%) were more frequent in BD when compared with the TD arm. Patients treated with BD had better outcomes than those treated with TD with regard to 1-year PFS and 3-year OS. Thus, BD was prioritized over TD for further investigations in Bor and Thal-naïve RRMM patients. (Clinical trial registration no. UMIN000003135.).