Phase I and pharmacokinetic study of erlotinib (OSI-774) in combination with docetaxel in squamous cell carcinoma of the head and neck (SSCHN)

Abstract

Purpose: This phase I study determined the maximal-tolerated dose, dose-limiting toxicities, pharmacokinetics, and recommended dose of erlotinib with docetaxel.

Patients and methods: Twenty-eight patients with head and neck cancer were enrolled. Patients were orally given erlotinib (50 mg) daily plus 35 mg/m² of docetaxel intravenously weekly × 3 every 4 weeks. Dose escalation of erlotinib was in 50-mg increments until toxicity. Pharmacokinetics were studied with LC-MS/MS, standard, and population pharmacokinetic methods.

Results: Ninety-five courses were successfully given (median 3, range 1-6). The most frequent side effects were diarrhea, fatigue, skin rash, anemia, and hypoalbuminemia. Dose de-escalation for both erlotinib and docetaxel was due to skin rash, neutropenia and/or severe infection with docetaxel to 25 mg/m² and erlotinib to starting dose of 50 mg and re-escalation of docetaxel to 35 mg/m². Responses were observed in 4/26 evaluable patients (100 mg erlotinib). In 24 patients, the mean Cmax and AUC erlotinib values increased with dose and following cumulative dosing (days 7 and 8 vs. day 1, p < 0.05). The CL/F (~7 L/h), V/F (~140 L), and t1/2 (~20 h) for erlotinib were similar to the reported. The mean AUC ratio of metabolite OSI-420 to erlotinib following repetitive dosing at 100 mg (+ or - docetaxel) showed a ~50% increase (p < 0.02), possibly suggesting self-enzyme induction. Population pharmacokinetic studies showed no significant covariate affecting erlotinib pharmacokinetics.

Conclusions: The combination of erlotinib and docetaxel was associated with significant toxicity, which limited the amount of administered erlotinib. Dosing for phase II trials was docetaxel 35 mg/m² and erlotinib 50 mg. The reason for excessive toxicity is not clear, but not due to change in pharmacokinetics.

Fig. 1

A set of representative plasma concentration–time profiles of erlotinib (OSI-774) and OSI-420 on day 1 and day 8 at 100-mg dose