Long-term safety of single-agent ibrutinib in patients with chronic lymphocytic leukemia in 3 pivotal studies

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 5 195) and PCYC-1115/1116 (RESONATE-2, n 5 135), and examined longer-term safety separately in the phase 1b/2 PCYC-1102/1103 study (n 5 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 5 173, 52% any-grade; n 5 15, 5% grade 3) and fatigue (n 5 119, 36% any-grade; n 5 10, 3% grade 3). The most common grade 3/4 AEs were neutropenia (n 5 60, 18%) and pneumonia (n 5 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 5 4), anemia (n 5 3), and atrial fibrillation (n 5 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.