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First-generation Bruton tyrosine kinase (BTK) inhibitor, ibrutinib, has been associated with an increased risk of cardiovascular toxicities. Zanubrutinib is a more selective, next-generation BTK inhibitor. In this analysis, incidence rates of atrial fibrillation, symptomatic (grade ≥2) ventricular arrhythmia, and hypertension were evaluated in a pooled analysis of 10 clinical studies with zanubrutinib monotherapy in patients (N = 1550) with B-cell malignancies and a pooled analysis of head-to-head studies comparing zanubrutinib with ibrutinib (ASPEN cohort 1; ALPINE). Among the 10 studies, most patients (median age, 67 years) were male (66.3%) and had CLL/SLL (60.5%). Overall incidence and exposure-adjusted incidence rates (EAIR) for atrial fibrillation, symptomatic ventricular arrhythmia, and hypertension were lower with zanubrutinib than ibrutinib. Despite a similar prevalence of preexisting cardiovascular events in ASPEN and ALPINE, atrial fibrillation/flutter incidence rates (6.1% vs 15.6%) and EAIR (0.2 vs 0.64 persons per 100 person-months; P < .0001) were lower with zanubrutinib than with ibrutinib. Symptomatic ventricular arrhythmia incidence was low for both zanubrutinib (0.7%) and ibrutinib (1.7%) with numerically lower EAIR (0.02 vs 0.06 persons per 100 person-months, respectively) for zanubrutinib. The hypertension EAIR was lower with zanubrutinib than ibrutinib in ASPEN but similar between treatment arms in ALPINE. The higher hypertension EAIR in ALPINE was inconsistent with other zanubrutinib studies. However, fewer discontinuations (1 vs 14) and deaths (0 vs 6) due to cardiac disorders occurred with zanubrutinib versus ibrutinib in ALPINE. These data support zanubrutinib as a treatment option with improved cardiovascular tolerability compared with ibrutinib for patients with B-cell malignancies in need of BTK inhibitors. These trials were registered at www.ClinicalTrials.gov as # NCT03053440, NCT03336333, NCT03734016, NCT04170283, NCT03206918, NCT03206970, NCT03332173, NCT03846427, NCT02343120, and NCT03189524.

Ibrutinib, a first-in-class once-daily oral Bruton tyrosine kinase inhibitor indicated for chronic lymphocytic leukemia (CLL), is continued until progressive disease or unacceptable toxicity. We conducted an integrated safety analysis of single-agent ibrutinib from randomized phase 3 studies PCYC-1112 (RESONATE, n = 195) and PCYC-1115/1116 (RESONATE-2, n = 135), and examined longer-term safety separately in the phase 1b/2 PCYC-1102/1103 study (n = 94, 420 mg/d). In the integrated analysis (ibrutinib treatment up to 43 months), the most common adverse events (AEs) were primarily grade 1/2; diarrhea (n = 173, 52% any-grade; n = 15, 5% grade 3) and fatigue (n = 119, 36% any-grade; n = 10, 3% grade 3). The most common grade 3/4 AEs were neutropenia (n = 60, 18%) and pneumonia (n = 38, 12%). Over time, prevalence of AEs of interest (diarrhea, fatigue, grade ≥3 infection, bleeding, and neutropenia) trended down; prevalence of hypertension increased, but incidence decreased after year 1. AEs led to dose reductions in 42 (13%) patients and permanent discontinuations in 37 (11%); dose modifications due to AEs were most common during year 1 and decreased in frequency thereafter. The most common AEs (preferred term) contributing to discontinuation included pneumonia (n = 4), anemia (n = 3), and atrial fibrillation (n = 3). With long-term follow-up on PCYC-1102/1103 (ibrutinib treatment up to 67 months), grade 3/4 AEs were generally similar to those in the integrated analysis. Overall, AEs were primarily grade 1/2 and manageable during prolonged ibrutinib treatment in patients with CLL. These trials were registered at www.clinicaltrials.gov as #NCT01578707, #NCT01722487, #NCT01724346, #NCT01105247, and #NCT01109069.