Immunomodulatory drug and dexamethasone-containing triple versus doublet combination treatments for relapsed or refractory multiple myeloma: a meta-analysis of phase III randomized controlled trials

Abstract

Background Triplet therapy has become the standard of care for relapsed or refractory multiple myeloma (RRMM) over the past few years. Prior to that, doublet therapy including dexamethasone and an immunomodulatory were standard. Several systematic studies have been conducted and many combinations with variable triplet therapies but have not always used the former standard therapy as a benchmark. The objective of this meta-analysis was to evaluate the efficacy and safety of triplet combinations that included dexamethasone and an immunomodulatory drug versus a doublet combination of just dexamethasone and an immunomodulatory for the treatment of RRMM. Methods A comprehensive literature search (PubMed, EMBASE, Cochrane Library) for phase III randomized controlled trials for efficacy and safety of triplet versus doublet combinations that specifically included dexamethasone and an immunomodulatory drug for treatment of RRMM. Efficacy (ORR, PFS, OS) and adverse events (≥ grade 3) were assessed using traditional statistical measures for aggregate data. Results Of 235 potential reports, 6 met the inclusion criteria (N = 115–792 participants). The methodological quality was ≥ 4 Jadad score for each. Triplet treatment had higher ORR (HR = 0.74, 95%CI: 0.65–0.84, P ≤ 0.001), PFS (HR = 0.63, 95%CI: 0.52–0.75, P ≤ 0.001), and OS (HR = 0.74, 95%CI: 0.65–0.84, P ≤ 0.001). The incidence of ≥ grade 3 diarrhea and fatigue were significantly higher in the triplet combination group. There was a trend toward increased incidence of ≥ grade 3 neutropenia, thrombocytopenia, thromboembolism, and peripheral neuropathy in the triplet therapy group. Notably, triplet therapy had a significantly lower rate of anemia compared to doublet therapy. Conclusions This study reinforces current guidelines and recommendations for triplet combinations containing dexamethasone and an immunomodulatory drug.