Phase II study of acalabrutinib in ibrutinib-intolerant patients with relapsed/refractory chronic lymphocytic leukemia

• Published in: Haematologica (Roma) Vol. 106; no. 9; pp. 2364 - 2373
• Main Authors: Rogers, Kerry A., Thompson, Philip A., Allan, John N., Coleman, Morton, Sharman, Jeff P., Cheson, Bruce D., Jones, Daniel, Izumi, Raquel, Frigault, Melanie M., Quah, Cheng, Raman, Rakesh K., Patel, Priti, Wang, Min Hui, Kipps, Thomas J.
• Format: Journal Article
• Language: English
• Published: Ferrata Storti Foundation 01.09.2021
• ISSN: 0390-6078; 1592-8721; 1592-8721
• DOI: 10.3324/haematol.2020.272500

B-cell receptor signalling inhibition by targeting Bruton tyrosine kinase (BTK) is effective in treating chronic lymphocytic leukemia (CLL). The BTK inhibitor ibrutinib may be intolerable for some patients. Acalabrutinib is a more selective BTK inhibitor that may be better tolerated by patients who are intolerant to ibrutinib. A phase 2 study of acalabrutinib was conducted in patients with relapsed/refractory CLL who were ibrutinib-intolerant and had continued disease activity. Intolerance was defined as having discontinued ibrutinib due to persistent grade 3/4 adverse events (AEs) or persistent/recurrent grade 2 AEs despite dose modification/interruption. Patients received oral acalabrutinib 100 mg twice daily until disease progression or intolerance. Sixty patients were treated. Overall response rate to acalabrutinib was 73% and three patients (5%) achieved complete remission. At median follow-up of 35 months, the median progressionfree and overall survival were not reached; 24-month estimates were 72% and 81%, respectively. The most frequent AEs with acalabrutinib were diarrhea (53%), headache (42%), contusion (40%), dizziness (33%), upper respiratory tract infection (33%), and cough (30%). Most common reasons for acalabrutinib discontinuation were progressive disease (23%) and AEs (17%). Most patients with baseline samples (49/52; 94%) and all with on-treatment samples (3/3; 100%) had no detectable BTK and/or PLCG2 mutations. Acalabrutinib is effective and tolerable in most patients with relapsed/refractory CLL who are intolerant of ibrutinib. Acalabrutinib may be useful for patients who may benefit from BTK inhibitor therapy but are ibrutinib intolerant.