Background: Recent clinical studies have shown that initial therapy with combined BRAF  and mitogen-activated extracellular signal-regulated kinase (MEK) inhibition is more effective in metastatic melanoma than single-agent BRAF  inhibitors. However, the response rates with single-agent BRAF  are low. Thus, the objective of this study was to conduct a meta-analysis of randomized controlled trials to compare the efficacy and adverse events risk between monotherapy and combination therapy.
Materials and methods: Searches were made in PubMed and EMBASE electronic databases and conference abstracts published by the American Society of Clinical Oncology from 2000 to 2017. Outcomes included overall response, progression-free survival, and overall survival, as well as the incidence rate of adverse events.
Results: Eight trials comprising 2,664 patients were included in the meta-analysis. Patients with combined therapies showed superior results compared to those with BRAF  inhibitors alone for the following: overall response rate (combined relative risk [RR] =1.34, 95% confidence interval [95% CI]: 1.24–1.45, P <0.00001), progression-free survival (combined hazards ratio [HR] =0.58, 95% CI: 0.52–0.64, P <0.00001), and overall survival rate (combined HR =0.70, 95% CI: 0.62–0.80, P <0.00001). Patients with combination therapies had higher incidence of adverse events including pyrexia (combined RR =2.00, 95% CI: 1.40–2.84), nausea (combined RR =1.41, 95% CI: 1.03–1.94), diarrhea (combined RR =1.50, 95% CI: 1.08–2.06), and vomiting (combined RR =1.87, 95% CI: 01.52–2.31) compared to those with BRAF  inhibitors alone.
Conclusion: These data suggested that the combined BRAF  and MEK inhibition was associated with a significant improvement in overall response, progression-free survival, and overall survival, but increased the incidence of adverse events among the patients with BRAF  V600-mutated metastatic melanoma. Further large-scale, high-quality, placebo-controlled, double-blind trials are needed to confirm this conclusion.
Keywords: efficacy, safety, melanoma, meta-analysis, BRAF  inhibition, MEK inhibition