A Phase I study of pazopanib in combination with gemcitabine in patients with advanced solid tumors.

PURPOSE: Pazopanib plus gemcitabine combination therapy was explored in patients with advanced solid tumors. METHODS: In a modified 3 + 3 enrollment scheme, oral once-daily pazopanib was administered with intravenous gemcitabine (Days 1 and 8, 21-day cycles). Three protocol-specified dose levels were tested: pazopanib 400 mg plus gemcitabine 1,000 mg/m(2), pazopanib 800 mg plus gemcitabine 1,000 mg/m(2), and pazopanib 800 mg plus gemcitabine 1,250 mg/m(2). Maximum-tolerated dose was based on dose-limiting toxicities during treatment Cycle 1. In the expansion phase, six additional patients were enrolled at the highest tolerable dose level. RESULTS: Twenty-two patients were enrolled. At the highest dose level tested (pazopanib 800 plus gemcitabine 1,250), patients received >80% of their planned dose and the regimen was deemed safe and tolerable. The most common treatment-related adverse events included fatigue, neutropenia, nausea, and decreased appetite. Neutropenia and thrombocytopenia were the most common events leading to dose modifications. Pharmacokinetic interaction between pazopanib and gemcitabine was not observed. One objective partial response at the highest dose was observed in a patient with metastatic melanoma. Prolonged disease stabilization (>12 cycles) was reported in three patients (metastatic melanoma, cholangiocarcinoma, and colorectal carcinoma). CONCLUSION: Combination pazopanib plus gemcitabine therapy is tolerable, with an adverse event profile reflective of that associated with the individual agents. There was no apparent pharmacokinetic interaction with pazopanib plus gemcitabine co-administration, although patient numbers were limited. Further investigation of combined pazopanib plus gemcitabine is warranted.

Phase I trial of pazopanib in patients with advanced cancer.

PURPOSE: The safety, pharmacokinetics, and clinical activity of pazopanib (GW786034), an oral angiogenesis inhibitor targeting vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit, were evaluated in patients with advanced-stage refractory solid tumors. EXPERIMENTAL DESIGN: Patients were enrolled into sequential dose-escalating cohorts (50 mg three times weekly to 2,000 mg once daily and 300-400 mg twice daily). Escalation or deescalation was based on toxicities observed in the preceding dose cohort. Pharmacokinetic and biomarker samples were obtained. Clinical response was assessed every 9 weeks. RESULTS: Sixty-three patients were treated (dose escalation, n = 43; dose expansion, n = 20). Hypertension, diarrhea, hair depigmentation, and nausea were the most frequent drug-related adverse events, the majority of which were of grade 1/2. Hypertension was the most frequent grade 3 adverse event. Four patients experienced dose-limiting toxicities at 50 mg, 800 mg, and 2,000 mg once daily. A plateau in steady-state exposure was observed at doses of >or=800 mg once daily. The mean elimination half-life at this dose was 31.1 hours. A mean target trough concentration (C(24)) >or=15 microg/mL (34 micromol/L) was achieved at 800 mg once daily. Three patients had partial responses (two confirmed, one unconfirmed), and stable disease of >or=6 months was observed in 14 patients; clinical benefit was generally observed in patients who received doses of >or=800 mg once daily or 300 mg twice daily. CONCLUSION: Pazopanib was generally well tolerated and showed antitumor activity across various tumor types. A monotherapy dose of 800 mg once daily was selected for phase II studies.