Phase I Safety and Pharmacokinetic Study of the PI3K/mTOR Inhibitor SAR245409 ( XL765) in Combination with Erlotinib in Patients with Advanced Solid Tumors

Introduction: The primary objectives of this phase I study were to evaluate the safety and maximum tolerated dose (MTD) of SAR245409, a pan-class I phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin inhibitor, combined with erlotinib in patients with advanced solid tumors. Methods: Forty-six patients with advanced solid tumors were enrolled. Patients with lung cancer (n = 37) had received an epidermal growth factor receptor (EGFR) inhibitor before study entry. SAR245409 30, 50, 70, or 90 mg once daily (QD) or 20 or 30 mg twice daily (BID) was administered, in combination with erlotinib 100 mg QD, in 28-day cycles. Dose escalation of SAR245409 followed a standard 3 + 3 design. Patients were evaluated for adverse events (AEs). Additional evaluations included pharmacokinetics, pharmacodynamic effects on PI3K and EGFR/mitogen-activated protein kinase signaling pathways in tumor and skin samples, and tumor response. Results: The MTDs of SAR245409, in combination with erlotinib 100 mg QD, were 70 mg QD and 20 mg BID. The most frequently reported treatment-related AEs (any grade) were diarrhea (35%), rash (35%), and nausea (28%). No treatment-related AE occurred at grade 3/4 in more than one patient (2.2%). No major pharmacokinetic interaction between SAR245409 and erlotinib was noted. Suppression of PI3K and EGFR/mitogen-activated protein kinase signaling pathway biomarkers was observed in skin and tumor samples. Stable disease was the best overall response reported, occurring in 12 of 32 (37.5%) evaluable patients. Conclusion: MTDs of SAR245409 and erlotinib were below the single-agent doses of either agent, despite the lack of major pharmacokinetic interaction.