Phase Ib Study of Binimetinib with Paclitaxel in Patients with Platinum-Resistant Ovarian Cancer: Final Results, Potential Biomarkers, and Extreme Responders.

Abstract

<b>Purpose:</b> Epithelial ovarian cancer (EOC) is a molecularly diverse disease. MEK inhibition targets tumors harboring MAPK pathway alterations and enhances paclitaxel-induced apoptosis in EOC. This phase Ib study evaluated the MEK inhibitor binimetinib combined with paclitaxel in patients with platinum-resistant EOC.<b>Patients and Methods:</b> Patients received intravenous weekly paclitaxel with oral binimetinib in three different administration schedules. Outcomes were assessed by RECIST and CGIC CA-125 response criteria. Tumor samples were analyzed using next-generation sequencing.<b>Results:</b> Thirty-four patients received ≥1 binimetinib dose. A 30-mg twice-a-day continuous or 45-mg twice-a-day intermittent binimetinib dose was deemed the recommended phase II dose (RP2D) in combination with 80 mg/m² i.v. weekly paclitaxel. Rate of grade 3/4 adverse events was 65%. The best overall response rate was 18%-one complete (CR) and four partial responses (PR)-among 28 patients with RECIST-measurable disease. Eleven patients achieved stable disease (SD), yielding a clinical benefit rate (CR+PR+SD) of 57%. Response rates, per both RECIST and CA-125 criteria, were highest in the 45-mg twice-a-day continuous cohort and lowest in the 45-mg twice-a-day intermittent cohort. All four evaluable patients with MAPK pathway-altered tumors experienced clinical benefit.<b>Conclusions:</b> The combination of binimetinib and intravenous weekly paclitaxel was tolerable in this patient population. The RP2D of binimetinib in combination with paclitaxel was 30 mg twice a day as a continuous or 45 mg twice a day as an intermittent dose. Although response rates were modest, a higher clinical benefit rate was seen in patients harboring alterations affecting the MAPK pathway. <i>Clin Cancer Res; 24(22); 5525-33. ©2018 AACR</i>.