A pharmacodynamically guided dose selection of PF-00337210 in a phase I study in patients with advanced solid tumors.

Purpose: PF-00337210 is an oral, highly selective vascular endothelial growth factor receptor (VEGFR) inhibitor. We evaluated a composite of biomarkers in real time to identify the recommended phase 2 dose (RP2D) and preliminary anticancer activity of PF-00337210.

Patients And Methods: Patients (Pts) with advanced cancers were treated once (QD) or twice daily (BID) with escalating doses. Acute effects on tumor perfusion and vascularity were assessed using DCE-MRI, weekly BP readings, soluble VEGFR-2, and hemoglobin levels.

Results: Forty-six pts were treated with 0.67-9 mg QD and 4-6 mg BID of PF-00337210. Nineteen pts (41%) previously received VEGF/VEGFR inhibitors. Two pts had dose-limiting toxicity (DLT) at 9 mg QD (troponin I increase and hypertension). The MTD at QD dose was 8 mg. Common drug-related adverse events were hypertension, fatigue, proteinuria, and nausea. Hypertension incidence and intensity corresponded with dose, but was well controlled with medication. Two confirmed partial responses and minor regressions (>10 to <30% reduction in target lesions) were noted. Complete DCE-MRI was acquired in 21 pts (20 evaluable for vascular response). Ten pts were vascular responders, including 5/6 pts at BID doses. Greatest modulation of soluble VEGFR-2 was at 6 mg BID. The maximum change from baseline in diastolic BP was higher at BID doses. There were no significant differences for systolic BP and hemoglobin levels.

Conclusions: PF-00337210 has profound VEGFR inhibition effects at well-tolerated doses. Antitumor activity and VEGF inhibition effects were observed across BID doses. The RP2D was 6 mg BID.