Comparison of the efficacy and safety of caplacizumab versus placebo in thrombotic thrombocytopenic purpura: a meta-analysis and systematic review based on randomized controlled trials

BACKGROUND: We conducted this meta-analysis to investigate the efficacy and safety of caplacizumab in patients with thrombotic thrombocytopenic purpura (TTP). TTP is a potentially fatal disorder characterized by systemic microvascular thrombosis. METHODS: Randomized controlled trials (RCTs) were conducted from PubMed, Embase, Cochrane Library and Web of Science, China National Knowledge Infrastructure (CNKI), VIP and Wanfang databases. RCTs of caplacizumab treatment for TPP were mainly included. Data from eligible studies were extracted and analyzed using relative effect sizes versus placebo use. The Cochrane bias assessment tool was used to assess the risk of bias of included studies, and the assessment results were presented graphically in Revman5.3. RESULTS: Four RCTs with a total of 416 patients were included, all of which were of high quality. Caplacizumab was associated with improvements in platelet counts normalization time [weighted mean difference (WMD) −1.18, 95% confidence interval (CI): −2.55 to 0.19, I(2)=69.9%, P=0.036], plasma exchange (PE) time (WMD −2.97, 95% CI: −4.44 to −1.50, I(2)=8.2%, P=0.163) and hospital stay (WMD −2.88, 95% CI: −4.56 to −1.21, I(2)=48.7%, P=0.036). In addition, the occurrence of adverse events was also investigated. The difference in mortality between the two groups was not statistically significant [relative risk (RR) 0.56, 95% CI: 0.18 to 1.72, I(2)=22.7%, P=0.275], relapse (RR 0.68, 95% CI: 0.13 to 3.49, I(2)=78.3%, P=0.01), or major thrombotic events (RR 1.01, 95% CI: 0.65 to 1.57, I(2)=43.4%, P=0.151). CONCLUSIONS: Caplacizumab shortens the platelet normalization time, PE time, and hospital stay in patients with TTP, and did not significantly increase the risk of adverse events. These results indicate that caplacizumab treatment provides significant benefits to patients with TTP. Even though this is evidence from RCTs, few original studies were included, so more multicenter RCTs are required.