Bortezomib-Containing Regimens for Multiple Myeloma Maintenance Therapy: a Meta-Analysis

Objective: To evaluate the efficacy and safety of bortezomib-containing regimens in maintenance therapy of multiple myeloma through meta-analysis of randomized controlled trials (RCTs).

Patients and methods: PubMed, Web of Science and ASH databases were searched for RCTs that investigated the treatment outcomes (progression-free survival [PFS] and overall survival [OS]) of maintenance therapy with bortezomib-containing regimens in patients with multiple myeloma. Study endpoints included PFS, OS, and grade 3 or 4 adverse events. Pooled hazard ratios (HRs) for survival outcomes and risk ratios (RRs) for dichotomous data with 95% confidence interval (CI) were calculated using Comprehensive MetaAnalysis (v2).

Results: Three RCTs comprising 1396 patients were included in this meta-analysis. Compared with maintenance therapy without bortezomib and/or no maintenance therapy, bortezomib-based maintenance therapy regimens significantly prolonged PFS (HR = 0.66, 95% CI = 0.58 - 0.76, P < 0.001) and OS (HR = 0.74, 95% CI = 0.62 - 0.88, P = 0.001) in multiple myeloma patients. In patients who received high-dose chemotherapy followed by autologous stem cell transplantation (ASCT), bortezomib-based maintenance therapy increased both PFS (HR = 0.73, 95% CI = 0.61 - 0.86, P < 0.001) and OS (HR = 0.76, 95% CI = 0.61 - 0.95, P = 0.016). For transplant ineligible patients, maintenance therapy with bortezomib-containing regimen also increased PFS (HR = 0.58, 95% CI = 0.47 - 0.71, P < 0.001) and OS (HR = 0.70, 95% CI = 0.52 - 0.92, P = 0.012). However, bortezomib-based maintenance therapy increased the risks of grade 3 or 4 adverse events including thrombocytopenia (RR = 1.37, 95% CI = 1.01 - 1.87, P = 0.046), infections (RR = 1.29, 95% CI = 1.02 - 1.64, P = 0.035), cardiac disorders (RR = 2.01, 95% CI = 1.17 - 3.47, P = 0.012), and vascular events (RR = 2.02, 95% CI = 1.15 - 1.45, P= 0.015).

Conclusions: Bortezomib-based maintenance therapy results in significant improvement in PFS and OS in multiple myeloma patients, but may increase the risk of developing some grade 3 or 4 adverse events, such as thrombocytopenia, infections, cardiac disorders, and vascular events. Further studies are needed to corroborate the above findings given the limited data on proteasome inhibitor based maintenance therapy for multiple myeloma.