Combination of a MEK inhibitor, pimasertib (MSC1936369B), and a PI3K/mTOR inhibitor, SAR245409, in patients with advanced solid tumors: Results of a phase Ib dose-escalation trial.

2530 Background: PI3K/mTOR and MAPK signaling pathways are often deregulated in tumors. Simultaneous inhibition of these pathways with the MEK1/2 inhibitor, pimasertib, plus the dual PI3K/mTOR inhibitor, SAR245409, (ClinicalTrials.gov NCT01390818) was investigated. Methods: This was a phase Ib, modified 3+3, dose-escalation trial in patients (pts) with advanced solid tumors. Pts received pimasertib and SAR245409 at the following dose levels (DLs): DL1, 15/30; DL2a, 30/30; DL2b, 15/50; DL3, 30/50; DL4a, 60/50; DL4b, 30/70; DL5, 60/70; DL6a, 90/70; DL6b 60/90 and DL7, 90/90 mg (once-daily, qd). After the qd maximum tolerated dose (MTD) was established, twice-daily (bid) dosing was tested: DL1a, 60/30; DL1b, 45/50 and DL2 60/50 mg bid. A recommended phase II dose (RP2D) was determined. Enrollment continued at the RP2D in four expansion cohorts (18 pts each): dual KRAS/PIK3CA mutated (mt) colorectal cancer (CRC), triple-negative breast cancer, KRAS mt non-small cell lung cancer (NSCLC) and BRAFmt melanoma. Re...