Ibrutinib, a Bruton tyrosine kinase inhibitor, is approved for treatment of various B-cell malignancies. In ibrutinib clinical studies, low-grade haemorrhage was common, whereas major haemorrhage (MH) was infrequent. We analysed the incidence of and risk factors for MH from 15 ibrutinib clinical studies (N=1768), including 4 randomised controlled trials (RCTs). Rates of any-grade bleeding were similar for single-agent ibrutinib and ibrutinib combinations (39% and 40%). Low-grade bleeding was more common in ibrutinib-treated than comparator-treated patients (35% and 15%), and early low-grade bleeding was not associated with MH. The proportion of MH in RCTs was higher with ibrutinib than comparators (4.4% vs. 2.8%), but after adjusting for longer exposure with ibrutinib (median 13months vs. 6months), the incidence of MH was similar (3.2 vs. 3.1 per 1000 person-months). MH led to treatment discontinuation in 1% of all ibrutinib-treated patients. Use of anticoagulants and/or antiplatelets (AC/AP) during the study was common (~50% of patients) and had an increased exposure-adjusted relative risk for MH in both the total ibrutinib-treated population (1.9; 95% confidence interval, 1.2-3.0) and RCT comparator-treated patients (2.4; 95% confidence interval, 1.0-5.6), indicating that ibrutinib may not alter the effect of AC/AP on the risk of MH in B-cell malignancies.
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