Acalabrutinib is a small-molecule BTK inhibitor designed to inhibit BTK signaling in B cells. Its pharmacologic activity supports its use in selected B-cell malignancies.
Pharmacodynamics
At 100 mg approximately every 12 hours, the FDA label reports median steady-state BTK occupancy of at least 95% in peripheral blood maintained over 12 hours. Acalabrutinib therefore produces substantial BTK target engagement across the recommended dosing interval.
Absorption
The geometric mean absolute bioavailability of acalabrutinib was approximately 25% in the FDA-described pharmacokinetic studies. Median time to peak plasma concentration was approximately 0.9 hours.
Food effect
A high-fat, high-calorie meal did not materially change overall exposure in the cited study, although maximum concentration decreased and the time to maximum concentration was delayed. The approved capsule product may be taken with or without food according to current U.S. labeling.
Distribution
Acalabrutinib is highly protein bound. FDA information reports reversible plasma-protein binding of approximately 97.5%, with the active metabolite ACP-5862 also highly protein bound.
Metabolism
Acalabrutinib is predominantly metabolized through CYP3A enzymes, with additional metabolic pathways contributing to clearance. ACP-5862 is a major active metabolite.
Half-life
The terminal elimination half-life of acalabrutinib itself is approximately one hour, while its active metabolite has a longer half-life. The short parent-drug half-life is one reason repeated dosing is used to maintain pharmacologic BTK inhibition.
Cardiac electrophysiology
FDA clinical pharmacology information indicates that a single acalabrutinib dose substantially above the recommended single dose did not produce a clinically relevant QTc prolongation in a dedicated study. This does not eliminate the separate clinical warning concerning cardiac arrhythmias.
Clinical evidence
Acalabrutinib has been studied extensively in CLL/SLL and MCL. EMA evidence reviews describe studies demonstrating clinically meaningful disease-control benefits in CLL and MCL populations.
Evidence limitations
Trial results apply to defined study populations and treatment regimens. They should not be interpreted as predicting an individual patient’s response or safety.