First-in-Human Phase I Study of GSK2126458, an Oral Pan-Class I Phosphatidylinositol-3-Kinase Inhibitor, in Patients with Advanced Solid Tumor Malignancies

Abstract

Although the MTD of GSK458 was 2.5 mg once daily, twice-daily dosing may increase duration of target inhibition. Fasting insulin and glucose levels served as pharmacodynamic markers of drug exposure. Select patients achieved durable responses; however,PIK3CAmutations were neither necessary nor predictive of response. Combination treatment strategies and novel biomarkers may be needed to optimally target PI3K.