Acalabrutinib Versus Ibrutinib in Previously Treated Chronic Lymphocytic Leukemia: Results of the First Randomized Phase III Trial

John C. Byrd, Peter Hillmen, Paolo Ghia, Arnon P. Kater, Asher Chanan-Khan, Richard R. Furman, Susan O’Brien, Mustafa Nuri Yenerel, Arpad Illés, Neil Kay, Jose A. Garcia-Marco, Anthony Mato, Javier Pinilla-Ibarz, John F. Seymour, Stephane Lepretre, Stephan Stilgenbauer, Tadeusz Robak, Wayne Rothbaum, Raquel Izumi, Ahmed HamdyPriti Patel, Kara Higgins, Sophia Sohoni, Wojciech Jurczak

Research output: Contribution to journalArticlepeer-review


PURPOSE Among Bruton’s tyrosine kinase inhibitors, acalabrutinib has greater selectivity than ibrutinib, which we hypothesized would improve continuous therapy tolerability. We conducted an open-label, randomized, noninferiority, phase III trial comparing acalabrutinib and ibrutinib in patients with chronic lymphocytic leukemia (CLL). METHODS Patients with previously treated CLL with centrally confirmed del(17)(p13.1) or del(11)(q22.3) were randomly assigned to oral acalabrutinib 100 mg twice daily or ibrutinib 420 mg once daily until progression or unacceptable toxicity. The primary end point was independent review committee–assessed noninferiority of progression-free survival (PFS). RESULTS Overall, 533 patients (acalabrutinib, n 5 268; ibrutinib, n 5 265) were randomly assigned. At the data cutoff, 124 (46.3%) acalabrutinib patients and 109 (41.1%) ibrutinib patients remained on treatment. After a median follow-up of 40.9 months, acalabrutinib was determined to be noninferior to ibrutinib with a median PFS of 38.4 months in both arms (95% CI acalabrutinib, 33.0 to 38.6 and ibrutinib, 33.0 to 41.6; hazard ratio: 1.00; 95% CI, 0.79 to 1.27). All-grade atrial fibrillation/atrial flutter incidence was significantly lower with acalabrutinib versus ibrutinib (9.4% v 16.0%; P 5 .02); among other selected secondary end points, grade 3 or higher infections (30.8% v 30.0%) and Richter transformations (3.8% v 4.9%) were comparable between groups and median overall survival was not reached in either arm (hazard ratio, 0.82; 95% CI, 0.59 to 1.15), with 63 (23.5%) deaths with acalabrutinib and 73 (27.5%) with ibrutinib. Treatment discontinuations because of adverse events occurred in 14.7% of acalabrutinib-treated patients and 21.3% of ibrutinib-treated patients. CONCLUSION In this first direct comparison of less versus more selective Bruton’s tyrosine kinase inhibitors in CLL, acalabrutinib demonstrated noninferior PFS with fewer cardiovascular adverse events.

Original languageEnglish (US)
Pages (from-to)3441-3452
Number of pages12
JournalJournal of Clinical Oncology
Issue number31
StatePublished - Nov 1 2021

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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