Acalabrutinib in Chronic Lymphocytic Leukemia: Pharmacology and Emerging Clinical Perspectives

Acalabrutinib, a second-generation Bruton's tyrosine kinase inhibitor (BTKi), is characterized by enhanced specificity and selectivity for BTK with minimal off-target effects, offering a significant evolution in the treatment of chronic lymphocytic leukemia (CLL). Its mechanism of action, a covalent binding to Cys481 within the BTK active site, ensures potent and sustained blockade of B cell receptor signaling, leading to disruption of key survival and proliferation pathways in malignant B cells. Long-term data from pivotal phase III trials confirmed the high efficacy of acalabrutinib-containing regimens in both treatment-naïve and relapsed/refractory CLL, showing durable progression-free survival, favorable overall survival rates, and low incidence of serious adverse events such as atrial fibrillation and hypertension, likely attributable to its improved selectivity, with limited immunosuppression and better tolerability leading to lower discontinuation rates compared to first-generation BTKi. Fixed-duration combination with acalabrutinib plus venetoclax, with or without obinutuzumab, has recently emerged as a highly efficacious strategy, providing sustained minimal residual disease (MRD) negativity with manageable toxicity, further supporting the clinical utility of acalabrutinib regimens. The demonstrated efficacy, robust safety, and flexibility of acalabrutinib in both continuous and fixed-duration regimens make it a cornerstone for individualized CLL management, enabling tailored treatment approaches based on patient- and disease-specific factors.