We investigated the safety and pharmacokinetics of a recombinant human monoclonal antibody to vascular endothelial growth factor (rhuMAb VEGF) in patients with cancer. Cohorts of patients with metastatic cancer having failed prior therapy entered a phase I trial of rhuMAb VEGF administered by a 90-minute intravenous infusion at doses from 0.1 to 10.0 mg/kg on days 0, 28, 35, and 42. Patients underwent pharmacokinetic sampling on day 0 and had serum samples obtained during the subsequent 28 days. Response assessment was carried out on days 49 and 72. Twenty-five patients with a median Eastern Cooperative Oncology Group performance status of 0 were accrued. There were no grade III or IV adverse events definitely related to the antibody. There were three episodes of tumor-related bleeding. Infusions of rhuMAb VEGF were well tolerated without significant toxicity. Grades I and II adverse events possibly or probably related to study drug included asthenia, headache, and nausea. Pharmacokinetics revealed a linear profile with a half-life of 21 days. There were no objective responses, though 12 patients experienced stable disease over the duration of the study. rhuMAb VEGF was safely administered without dose-limiting toxicity at doses ranging up to 10 mg/kg. Multiple doses of rhuMAb VEGF were well tolerated, and pharmacokinetic studies indicate that doses of > or = 0.3 mg/kg have a half-life similar to that of other humanized antibodies. Subsequent trials will explore rhuMAb VEGF alone and in combination chemotherapy.