Population pharmacokinetics of erlotinib and its pharmacokinetic/pharmacodynamic relationships in head and neck squamous cell carcinoma.

Unlabelled: A clinical study was conducted to determine the safety and efficacy of neoadjuvant erlotinib treatment in patients with head and neck squamous cell carcinoma [Thomas F, Rochaix P, Benlyazid A, et al. Pilot study of neoadjuvant treatment with erlotinib in non-metastatic head and neck squamous cell carcinoma. Clin Cancer Res 2007;13:7086-92]. The aim of the present analysis was to explore the impact of several covariates on the pharmacokinetics of erlotinib and its main metabolite (OSI-420) and to determine PK/PD relationships.

Patients And Methods: Plasma concentrations of erlotinib and OSI-420 of 42 patients were analysed using the NONMEM program to evaluate the impact of patients' covariates on erlotinib pharmacokinetics. The presence of single nucleotide polymorphisms (SNP) in ABCB1 (2677G>T/A and 3435C>T), ABCG2 (421C>A) and CYP3A5 (6986G>A) was investigated. Pharmacokinetic/pharmacodynamic relationships between plasma drug exposure (AUC) and early drug response or toxicity were also studied.

Results: The covariates retained to predict erlotinib clearance were ALAT (alanine amino transferase), age and ABCG2 polymorphism. A significant link between drug exposure and the grade of skin rash was observed but early response to treatment was not correlated to the erlotinib AUC.

Conclusions: Erlotinib treatment may present criteria justifying dose individualisation but further studies, including more patients, are necessary to define the modalities of this adaptation.