Objective: To investigate the efficacy and toxicity of bortezomib of different doses in combination with dexamethasone for the treatment of relapsed or refractory multiple myeloma (MM).
Methods: 23 patients with relapsed or refractory MM, 10 males and 13 females, aged 65 (42-86), were randomized to 2 groups: low dose group receiving intravenous 1.0 mg/m2 bortezomib (n=10) on days 1, 4, 6, and 11 (twice weekly) combined with dexamethasone 20 mg/d on days 1-4, with 3 weeks as a course of treatment, and (20 standard dose group: receiving intravenous 1.3 mg/m2 bortezomib (n=13) combined with dexamethasone. The patients were followed up for 9.5 (3-15) months. The effect was determined using modified European Group for Blood and Marrow Transplantation (EBMT) criteria.
Results: The complete response (CR) + partial response (PR) rate of the 1.0 mg/m2 bortezomib group was 70.0%, not significantly different from that of the 1.3 mg/m2 bortezomib group (61.5%, P > 0.05). The relief rate (CR + near CR rate) of the 1.0 mg/m2 bortezomib group was 20.0% not significantly different from that of the 1.3 mg/m2 bortezomib group (38.5%, P > 0.05). Only 1 case of adverse event over the grade 3 of National Cancer Institute Common Terminology Criteria for Adverse Events occurred in the 1.3 mg/m2 bortezomib group. Five cases of infectious fever and 2 cases of treatment-associated death occurred in the 1.3 mg/m2 bortezomib group.
Conclusion: Bortezomib at the dose of 1.3 mg/m2 is more effective in treatment of relapsed or refractory MM than that at the dose of 1.3 mg/m2 and has more side effects.