A phase I clinical, pharmacokinetic, and pharmacodynamic study of weekly or every three week ixabepilone and daily sunitinib in patients with advanced solid tumors

Abstract

Purpose: To evaluate the safety, MTD, pharmacokinetics/pharmacodynamics, and early clinical activity of ixabepilone given either weekly or every 3 weeks in combination with daily sunitinib in patients with advanced solid tumors. Experimental Design: Eligible patients received either weekly (schedule A) or every 3 weeks (schedule B) ixabepilone at escalating doses (schedule A: 7.5, 15, or 20 mg/m2; schedule B: 20, 30, or 40 mg/m2), and oral sunitinib (37.5 mg daily), starting on day 8 of cycle 1. Dose-limiting toxicities (DLT) were assessed during cycle 1. Results: The ixabepilone and sunitinib combination was fairly well tolerated. DLTs were observed in 3 subjects (1 in schedule 3A and 2 in schedule 3B). The most common grade 3-4 hematologic and nonhematologic adverse events were leukopenia and fatigue, respectively. Four patients (3 in schedule A) achieved a partial response, while 13 patients had stable disease. Nine of 17 heavily pretreated colorectal cancer patients had clinical benefit. Coadministration of sunitinib with ixabepilone on a weekly (but not every 3 week) schedule was associated with a significant increase in the half-life and a significant decrease in the clearance of ixabepilone. Correlative studies demonstrated a significant association between higher baseline plasma angiogenic activity (PAA) and clinical benefit in schedule A patients. Weekly, but not every 3 weeks, ixabepilone led to a significant decrease in PAA postbaseline. Conclusions: Coadministration of ixabepilone with sunitinib has acceptable toxicity and encouraging clinical activity in heavily pretreated patients, particularly in patients with metastatic colorectal cancer.