Combination therapy with gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, gemcitabine and cisplatin in patients with advanced solid tumors

Background: The aim of this study was to investigate the tolerability, pharmacokinetic, interaction and antitumor activity of gefitinib ('Iressa', ZD1839), an orally active, selective epidermal growth factor receptor tyrosine kinase inhibitor, combined with gemcitabine and cisplatin in chemotherapy-naive patients with advanced solid tumors. Patients and methods: This was an open-label feasibility trial evaluating two doses of gefitinib (250 and 500 mg/day) in combination with gemcitabine and cisplatin. Gefitinib was administered daily from day 2 onwards. Gemcitabine 1250 mg/m(2) was given on days 1 and 8 and cisplatin 80 mg/m(2) on day 1 for up to six 3-week cycles. Patients could then continue to receive gefitinib monotherapy. Results: Eighteen patients were entered, nine at each gefitinib dose level. Two patients developed dose-limiting toxicity: one grade 3 convulsion (250 mg/day dose group) and one grade 3 rash (500 mg/day dose group). The most frequently occurring adverse events in the combination phase were vomiting (17 patients), asthenia (16), nausea (14), diarrhea (14) and skin rash (13). The most common grade 3/4 adverse events were vomiting (seven patients), asthenia (six), thrombocytopenia (six), diarrhea (five) and anorexia (five). Pharmacokinetic analyses showed no apparent pharmacokinetic interaction between gefitinib and cisplatin or gemcitabine, with the exception of a possible small increase in the geometric mean exposure to gemcitabine seen on day 8 of therapy when given alone with the higher dose of gefitinib. Of 17 evaluable patients, nine had confirmed partial responses, seven had stable disease and one had progressive disease. Conclusions: Combination therapy of gefitinib with cisplatin and gemcitabine had a manageable and predictable safety profile, no major effect on exposure to any of the three drugs and antitumor activity.