Purpose: To investigate the tolerability, pharmacokinetics, and antitumor activity of the oral, selective epidermal growth factor receptor-tyrosine kinase inhibitor ZD1839 in patients with solid malignant tumors.
Patients and methods: This was an open, phase I, escalating multiple-dose tolerability and pharmacokinetic trial. ZD1839 was administered once daily for 14 consecutive days followed by 14 days off treatment. Dose escalation started at 50 mg/d and continued to 925 mg or until consistent dose-limiting toxicity (DLT) was observed.
Results: Sixty-four patients were entered at eight dose levels. The most frequent dose-related grade 1 and 2 adverse events were an acne-like (or folliculitis) rash, nausea, and diarrhea. Three of nine patients treated at 700 mg/d developed DLT (reversible grade 3 diarrhea); grade 3 and 4 events were uncommon. Exposure to ZD1839 was dose proportional, and the mean terminal half-life was 48 hours (range, 37 to 65). Four of 16 patients with non-small-cell lung cancer (NSCLC) had objective partial responses observed from ZD1839 300 to 700 mg/d. Overall, 16 patients remained on study for > or = 3 months, with seven of these patients (five with NSCLC, including three of the patients with partial response) remaining on study for > or = 6 months.
Conclusion: ZD1839 was well tolerated, with DLT observed at a dose well above that at which antitumor activity was seen. Pharmacokinetic analysis confirmed that ZD1839 was suitable for administration as a once-daily oral tablet formulation. Phase II monotherapy and phase III combination trials in NSCLC are being conducted to investigate further the efficacy, tolerability, and optimal daily dose of ZD1839.