Results from a Real-World Multicenter Analysis of 482 Patients with Chronic Lymphocytic Leukemia Treated with Ibrutinib: A Look at Racial Differences

Background Despite recent approvals of lifesaving treatments for chronic lymphocytic leukemia (CLL), real-world data on the tolerability of the Bruton tyrosine kinase inhibitor ibrutinib for CLL treatment are lacking, especially in Black patients. Objective To expand upon a previously reported retrospective chart review of ibrutinib-treated patients with CLL to increase the number of sites and the enrollment period in first-line (1L) and relapsed/refractory (R/R) settings with a subanalysis based on ethnicity. Patients and Methods Adults with CLL who initiated ibrutinib treatment from five centers were followed for ≥ 6 months. Results We identified 482 patients with CLL [405 White (153 1L, 252 R/R), 37 Black (17 1L, 20 R/R), 40 other/unidentified]. At baseline, 58.5% of all patients (68.8% of Black patients) had hypertension. At a median follow-up of 28.2 months, 31.1% of patients overall discontinued ibrutinib, 16.2% due to adverse events (12.2% 1L, 18.8% R/R). Overall, 46.0% of patients experienced ≥ 1 dose hold (40.2% 1L, 49.8% R/R), and 28.8% of patients experienced ≥ 1 dose reduction (24.9% 1L, 31.4% R/R). Among Black patients, ibrutinib was discontinued in 24.3% of patients (17.6% 1L, 30.0% R/R), 8.1% due to disease progression and 5.4% due to adverse events; 40.5% of patients experienced ≥ 1 dose hold (35.3% 1L, 45.0% R/R), and 32.4% of patients experienced ≥ 1 dose reduction (23.5% 1L, 40.0% R/R). Conclusions Toxicity and disease progression were the most common reasons for ibrutinib discontinuations in the overall population and among Black patients, respectively. Encouraging research participation of underrepresented patient groups will help clinicians better understand treatment outcomes. Plain Language Summary Ibrutinib, a Bruton tyrosine kinase inhibitor, is an approved oral targeted therapy for the treatment of chronic lymphocytic leukemia (CLL). Patients treated with ibrutinib can experience side effects (referred to as adverse events) and may need to reduce the drug dose (referred to as dose reductions) or stop treatment (referred to as discontinuations) for a variety of reasons. A previous study showed that patients who were treated with ibrutinib experienced frequent dose reductions and discontinuations. This study described dose reductions and discontinuations in a larger patient population treated with ibrutinib and also described outcomes in Black patients. Patients with CLL treated with ibrutinib were identified from five medical cent