Clinical implications of crizotinib pharmacokinetics

Purpose:We assessed the effect of baseline patient demographic and disease characteristics on the crizotinib pharmacokinetic parameters oral clearance (CL/F), volume of distribution (V2/F), and area-under-the-curve at steady state (AUCss) following multiple crizotinib 250-mg twice-daily dosing in patients with ALK-positive cancer. Experimental Design:A pharmacokinetic model was fit to data from 1,214 patients. We identified statistically significant covariates (P{less than or equal to}0.001) by evaluating their effects on CL/F and V2/F and estimated their magnitudes. Results:Age, Eastern Cooperative Oncology Group performance status, aspartate aminotransferase (AST) levels, albumin levels, and smoking status had no effect on CL/F or V2/F. Statistically significant covariates were Asian race and female sex for CL/F and V2/F and body weight, creatinine clearance (CLcr), and total bilirubin for CL/F only. The model predicted that CL/F would be 9% lower or higher in a 40-kg or a 100-kg patient, respectively; 16% lower in patients with CLcr 30 mL/min; 23% lower in Asians; and 11% lower in females than the reference patient (65-kg non-Asian male; baseline CLcr, 91.6 mL/min; total bilirubin, 0.41 mg/dL). The effect of total bilirubin on CL/F was small. V2/F was 23% lower in Asians than non-Asians and females than males. Effects of all significant covariates on AUCss were not predicted to be clinically relevant. Conclusions:Crizotinib at a 250-mg twice-daily starting dose appears to be appropriate for all patients irrespective of age, sex, race, body weight, mild or moderate renal impairment, or hepatic function (in the range evaluated: bilirubin {less than or equal to}2.1 mg/dL or AST {less than or equal to}124 U/L).

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