Risk of bleeding associated with BTK inhibitor monotherapy: a systematic review and meta-analysis of randomized controlled trials

The bleeding risk associated with Bruton's tyrosine kinase inhibitor (BTKi) monotherapy remains to be understood. This systematic review aims to evaluate BTKi monotherapy related bleeding risk.PubMed, Embase, and CENTRAL were searched up to 5 December 2021. We included randomized controlled trials (RCTs) comparing BTKi monotherapy with control drugs, or comparing different BTKi monotherapies.10 studies with 3139 patients were included. Ibrutinib (vs. control drugs) significantly increased the risk of overall bleeding and major bleeding (RR = 2.22, 95% CI 1.80-2.75, P < 0.00001; RR = 1.80, 95% CI 1.02-3.18, P = 0.04, respectively). Acalabrutinib (vs. control drugs) had a significantly increased overall bleeding risk (RR = 3.45, 95% CI 2.39-4.99, p < 0.00001). A significant difference was found in overall bleeding between ibrutinib and acalabrutinib (RR = 1.35, 95% CI 1.11-1.64, P = 0.002). Compared to zanubrutinib, ibrutinib tended to increase the risk of major bleeding (RR = 1.55, 95% CI 0.57-4.18, P = 0.39).Ibrutinib and acalabrutinib (vs. control drugs) have a higher risk of bleeding and overall bleeding, respectively. Limited evidence suggests that ibrutinib (vs. acalabrutinib) significantly increases overall bleeding risk, but the differences are not observed in other comparisons.