Risk of Major Bleeding with Ibrutinib in Patients with Thrombocytopenia - a Retrospective Single-Center Canadian Study

Introduction: Ibrutinib, an oral Bruton Kinase inhibitor, is a highly effective treatment for patients with chronic lymphocytic leukemia (CLL). Previous studies reported an increased risk of bleeding due to impaired platelet function. Patients with CLL experience significant thrombocytopenia, which increases their risk for bleeding. This population was excluded from major trials and data is lacking to inform management in this setting. Methods: This is a single center retrospective study of all adult patients with CLL who received single agent ibrutinib in London, Ontario, Canada between January 2014 to December 2020. The primary objective was to investigate the risk of major bleeding associated with thrombocytopenia. Secondary objective was to investigate potential predictors of bleeding. Bleeding events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) grading system. A major bleed was defined as CTCAE grade 3 or higher as well as bleeding in the central nervous system. To assess the effect of independent variables on the outcome of bleeding, univariate analysis using chi square and t-tests was performed. Multivariate analysis was then preformed with the variables that were significant (p