Clinical evaluation of ZD6474, an orally active inhibitor of VEGF and EGF receptor signaling, in patients with solid, malignant tumors.

BACKGROUND ZD6474 selectively inhibits the tyrosine kinase activity of vascular endothelial growth factor receptor and epidermal growth factor receptor. The safety, tolerability and pharmacokinetics of ZD6474 were assessed in a phase I dose-escalation study of patients with advanced solid tumors. PATIENTS AND METHODS Adult patients with tumors refractory to standard treatments received once-daily oral ZD6474 (50-600 mg) in 28-day cycles, until disease progression or unacceptable toxicity was observed. RESULTS Seventy-seven patients were treated at doses of 50 mg (n=9), 100 mg (n=19), 200 mg (n=8), 300 mg (n=25), 500 mg (n=8), and 600 mg (n=8). Adverse events were generally mild, and the most common dose-limiting toxicities (DLT) were diarrhea (n=4), hypertension (n=4), and rash (n=3). The incidence of most adverse events appeared to be dose-dependant. In the 500 mg/day cohort, 3/8 patients experienced DLT and this dose was therefore considered to exceed the maximum tolerated dose. Pharmacokinetic analysis confirmed that ZD6474 was suitable for once-daily oral dosing. CONCLUSIONS Once-daily oral dosing of ZD6474 at 300 mg/day is generally well tolerated in patients with advanced solid tumors, and this dose is being investigated in phase II trials.