Monoclonal Antibodies versus Histone Deacetylase Inhibitors in Combination with Bortezomib or Lenalidomide plus Dexamethasone for the Treatment of Relapsed or Refractory Multiple Myeloma: An Indirect-Comparison Meta-Analysis of Randomized Controlled Trials

During the past decades, agents with novel mechanisms of action, such as monoclonal antibodies (MAbs) and histone deacetylase inhibitors (HDACis) have been applied to treat relapsed or refractory multiple myeloma (RRMM). The treatment outcomes of MAbs versus HDACi in combination with bortezomib or lenalidomide plus dexamethasone remain unknown. We conducted this meta-analysis to compare indirectly the efficacy and safety of MAbs and HDACis in combination with bortezomib or lenalidomide plus dexamethasone. Six trials (eight articles) were included in the meta-analysis with 3270 RRMM patients enrolled. We synthesized hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS), risk ratios (RRs) for complete response (CR),very good partial response (VGPR), overall response (OR), progressive disease plus stable disease (PD + SD) and common at least grade 3 adverse events, and their corresponding 95%confidence intervals (95% CI). Treatment with MAbs in combination with bortezomib or lenalidomide plus dexamethasone resulted in longer PFS (HR 0.83, 95% CI: 0.66–0.98), fewer incidences of at least grade 3 thrombocytopenia (RR 0.35, 95% CI: 0.23–0.53), neutropenia (RR 0.70, 95% CI: 0.51–0.96), and sense of fatigue (RR 0.37, 95% CI: 0.17–0.82) than HDACis. The daratumumab plus bortezomib or lenalidomide and dexamethasone might significantly improve PFS in comparison with HDACis plus bortezomib or lenalidomide and dexamethasone (HR 0.55, 95% CI: 0.40–0.74). In conclusion, MAbs may be superior to HDACis in achieving longer PFS and may be better tolerated when in combination therapy with bortezomib or lenalidomide plus dexamethasone.