Bortezomib and low-dose dexamethasone with or without continuous low-dose oral cyclophosphamide for primary refractory or relapsed multiple myeloma: a randomized phase III study

This phase III, open-label, randomized, controlled study aimed to evaluate the benefit of adding continuous low-dose oral cyclophosphamide to bortezomib-dexamethasone in patients with primary relapsed/refractory multiple myeloma. Patients were randomized 1:1 to receive up to eight 3-week cycles of bortezomib (1.3 mg/m²) and dexamethasone (20 mg; VD; n = 48) or bortezomib-dexamethasone plus oral cyclophosphamide (50 mg; VCD; n = 48). Median time to progression (primary endpoint) was slightly longer in the VD versus VCD group (12.6 vs 9.9 months, P = 0.192), and the hazard ratio for disease progression was in favor of VD (hazard ratio = 0.71, 95% confidence interval = 0.43–1.19, P = 0.196). The overall response rate was 74% with VD and 70% with VCD. Most adverse events were similar in frequency between arms; however, grade ≥ 3 peripheral neuropathy was more frequent in the VCD versus VD arm (15 vs 4%). Infection rate was higher in the VCD arm (64 vs 52%); however, grade ≥3 infection rates were comparable (19 vs 17%). Further trials are needed to determine whether addition of cyclophosphamide to VD at a different dose/schedule confers clinical benefit. This study was terminated prematurely, with insufficient sample size to adequately compare the arms; the results should, therefore, be considered descriptive. This trial is registered: EudraCT Number 2008-003213-27; ClinicalTrials.​gov NCT00813150.