A phase I trial of LY2584702 tosylate, a p70 S6 kinase inhibitor, in patients with advanced solid tumours

Abstract

BackgroundLY2584702 tosylate (hereafter referred to as LY2584702) is a potent, highly selective adenosine triphosphate (ATP) competitive inhibitor against p70 S6 kinase, a downstream component of the phosphatidylinositol-3-kinase signalling pathway which regulates cell proliferation and survival. LY2584702 exhibited anti-tumour activity in preclinical analysis. MethodsPatients with advanced solid tumours were treated with LY2584702 orally on a 28-day cycle until the criteria for maximum tolerated dose (MTD) were met. Skin biopsies were collected for pharmacodynamic analysis, and levels of phospho-S6 protein were examined. The primary objective was to determine a phase II dose and schedule with secondary objectives of observing safety and tolerability. Dose escalation was based upon Common Terminology Criteria for Adverse Events Version 3.0. ResultsThirty-four patients were enrolled onto this phase I study and treated with LY2584702 on a QD (once-daily) or BID (twice-daily) dosing schedule. Part A dose escalation (n=22) began with 300mg BID (n=2). Due to toxicity, this was scaled back to doses of 25mg (n=3), 50mg (n=8), 100mg (n=3), and 200mg (n=6) QD. Part B dose escalation (n=12) included 50mg (n=3), 75mg (n=3), and 100mg (n=6) BID. Seven patients experienced dose-limiting toxicity (DLT). All DLTs were Grade 3 and included vomiting, increased lipase, nausea, hypophosphataemia, fatigue and pancreatitis. ConclusionThe MTD was determined to be 75mg BID or 100mg QD. No responses were observed at these levels. Pharmacokinetic analysis revealed substantial variability in exposure and determined that LY2584702 treatment was not dose proportional with increasing dose.