A phase I study of sunitinib plus bevacizumab in advanced solid tumors.

Abstract

Bevacizumab is an antibody against vascular endothelial growth factor; sunitinib is an inhibitor of vascular endothelial growth factor and related receptors. The safety and maximum tolerated dose of sunitinib plus bevacizumab was assessed in this phase I trial. Patients with advanced solid tumors were treated on a 3+3 trial design. Patients received sunitinib daily (starting dose level, 25 mg) for 4 weeks on followed by 2 weeks off and bevacizumab (starting dose level, 5 mg/kg) on days 1, 15, and 29 of a 42-day cycle. Dose-limiting toxicities during the first 6-week cycle were used to determine the maximum tolerated dose. Thirty-eight patients were enrolled. Patients received a median of 3 cycles of treatment (range, 1-17(+)). There was one dose-limiting toxicity (grade 4 hypertension) at 37.5 mg sunitinib and 5 mg/kg bevacizumab. Grade 3 or greater toxicity was observed in 87% of patients including hypertension (47%), fatigue (24%), thrombocytopenia (18%), proteinuria (13%), and hand-foot syndrome (13%). Dose modifications and delays were common at higher dose levels. No clinical or laboratory evidence of microangiopathic hemolytic anemia was observed. Seven patients had a confirmed Response Evaluation Criteria in Solid Tumors-defined partial response (18%; 95% confidence interval, 8-34%). Nineteen of the 32 patients with a postbaseline scan (59%) had at least some reduction in overall tumor burden (median, 32%; range, 3-73%). The combination of sunitinib and bevacizumab in patients with advanced solid tumors is feasible, albeit with toxicity at higher dose levels and requiring dose modification with continued therapy. Antitumor activity was observed across multiple solid tumors.