A phase lb, open-label, multicenter, dose-escalation study of the oral pan-PI3K inhibitor BKM120 in combination with the oral MEK1/2 inhibitor GSK1120212 in patients (pts) with selected advanced solid tumors.

Abstract

3003 Background: MAPK and PI3K/AKT signaling pathways regulate proliferation, differentiation and cell death in human cancers. Known interaction between the 2 pathways provides the rationale for combining both inhibitors in a phase I study. Methods: The objective is to determine the maximum tolerated dose (MTD) and/or recommended phase II dose (RP2D) for oral, daily administered, BKM120 + GSK1120212, mainly in pts with tumors with RAS/RAF mutations (mt). A Bayesian logistic regression model with overdose control guides the dose escalation of the treatment. Secondary objectives include safety, tolerability, PK and efficacy. Results: As of 22.09.11, 49 pts were treated with BKM120 + GSK1120212 as follows: 30mg + 0.5mg, 60mg + 0.5mg, 60mg + 1.0mg, 60mg + 1.5mg, 60mg + 2.0mg, 70mg + 1.5mg, 80mg + 1.0mg, 80mg + 1.5mg. 6 pts had dose-limiting toxicities (DLTs); all were reversible. Grade 3 DLTs were: 3 x stomatitis, 1 x dysphagia, 1 x LVEF decrease, 1 x CK increase, 1 x nausea, 1 x anorexia, 1 x decreased oral intake. MTD and/or RP2D for the combination have not been reached. Most common adverse events (AEs) (>25%), all grades and causality, were dermatitis acneiform, diarrhea (51% each); nausea (41%); vomiting (37%); rash (33%); asthenia (31%); CK increase, decreased appetite, pyrexia or stomatitis (29% each) and hyperglycemia (27%). There were 4 on-treatment deaths unrelated to treatment. AEs led to treatment discontinuation, 17 pts (35%) and interruptions/dose reductions, 25 pts (51%). Apparent steady-states of BKM120 and GSK1120212 were reached by day 28. Plasma concentrations of BKM120 in combination with GSK1120212 were lower than for monotherapy. Exposure to GSK1120212 with BKM120 was similar to that observed in monotherapy studies. 3 confirmed partial responses have been observed in pts with KRAS mt ovarian cancer; 2 lasting >9 months. 2 patients with BRAF mt melanoma, who had previously progressed on BRAF inhibitors, had stable disease, for 1 of whom treatment is still ongoing in cycle 6. Conclusions: BKM120 and GSK1120212 can be safely combined. Signs of clinical activity have been seen in pts with RAS/RAF mt tumors.