Phase I trial of fixed dose-rate gemcitabine in combination with carboplatin in chemonaive advanced non-small-cell lung cancer: a Cancer Therapeutics Research Group study.

PURPOSE: To determine the maximally tolerated dose (MTD) of gemcitabine administered at a fixed dose-rate of 10 mg/m(2) per min in combination with fixed dose carboplatin, to evaluate the toxicity of this regimen and to determine the pharmacokinetics of plasma gemcitabine.
METHODS: Patients with advanced stage non-small-cell lung cancer (NSCLC) received carboplatin (AUC 5) on day 1 followed by gemcitabine at a fixed dose rate of 10 mg/m(2) per min in escalating durations of infusion on days 1 and 8 every 21 days. Pharmacokinetic sampling was obtained on day 1, cycle 1 of treatment.
RESULTS: A total of 15 patients received carboplatin and gemcitabine in cohorts of three to six patients at three dose levels. The doses of gemcitabine studied were 600, 750, and 900 mg/m(2). The MTD was reached at 900 mg/m(2). Dose-limiting toxicities were thrombocytopenia and liver failure, and with repeated dosing neutropenia was commonly observed. The recommended phase II dose of gemcitabine was 750 mg/m(2). Partial responses were observed at 600 and 750 mg/m(2) of gemcitabine. Plasma gemcitabine did not reach steady state except in one patient with the durations of infusion studied. Plasma concentrations, however, were above 10 micro mol/l between 20 and 90 min in all patients.
CONCLUSIONS: Gemcitabine administered as a 75-min infusion at a fixed dose rate of 10 mg/m(2)/min on days 1 and 8 in combination with carboplatin on day 1 every 21 days is tolerable and active in NSCLC. Pharmacokinetic studies demonstrated that the target plasma gemcitabine concentration above 10 micro mol/l was achieved. Further studies are warranted to compare this regimen against standard regimens of carboplatin and gemcitabine.