Phase I study of safety, tolerability, and pharmacokinetics of pazopanib in combination with oral topotecan in patients with advanced solid tumors.
2536 Background: To determine the maximum-tolerated dose (MTD), safety, tolerability and pharmacokinetics of the oral anti-angiogenic drug pazopanib in combination with oral topotecan, an inhibitor of topoisomerase-I. Methods: Two-stage, two-arm, dose escalation and pharmacokinetic phase I study of pazopanib and oral topotecan in patients with advanced solid tumors, (NCT00732420, www.clinicaltrials.gov). This interim report describes the bioavailability and safety results for daily pazopanib combined with oral topotecan (days 1, 8, 15) in a 28-day cycle. Results: Twenty-eight of 32 patients completed at least one cycle and were evaluable for analysis. Three dose-limiting toxicities (DLTs) occurred: grade 3 hand-foot-syndrome, diarrhea and neutropenia. Pazopanib 800 mg/topotecan 10 mg exceeded the MTD with two DLTs in six patients. The most frequent treatment-related toxicities were grade 3 anemia (3/28), leukocytopenia, neutropenia and fatigue (2/28 each). One death due to hepatic failure occurred at pazopanib 800mg/toptecan 2mg in a heavily pre-treated patient with sarcoma that may have been related to paracetamol ingestion but attribution to the pazopanib can not be excluded. Topotecan AUC0-∞ increased 1.58-fold (90%CI: 1.09–1.29) and Cmax increased 1.78-fold (90%CI: 1.08-2.92) when given with pazopanib compared to single administration (n=7). Pazopanib AUC0-24 and Cmax ratios were not increased when co-administered with topotecan: 0.98 (90%CI: 0.95-1.02) and 0.96 (90%CI: 0.92-1.01). Twenty-three patients were evaluable for response (RECIST): PR (2/23; 9%, both ovarian cancer); SD (13/23; 57%) and PD (8/23; 35%). Pazopanib 800 mg/topotecan 8 mg is currently being explored in an expansion cohort. A second treatment arm of pazopanib 800 mg with topotecan daily x5 is ongoing and will be reported separately. Conclusions: Daily pazopanib and weekly oral topotecan is tolerable with handfoot syndrome, neutropenia and fatigue as dose limited side effects. Pazopanib increased topotecan exposure 1.58-fold (AUC0-∞) and 1.78-fold (Cmax). Clinical trial information: NCT00732420.