Synergy of WEE1 and mTOR Inhibition in Mutant KRAS -Driven Lung Cancers.

Purpose: KRAS -activating mutations are the most common oncogenic driver in non-small cell lung cancer (NSCLC), but efforts to directly target mutant KRAS have proved a formidable challenge. Therefore, multitargeted therapy may offer a plausible strategy to effectively treat KRAS -driven NSCLCs. Here, we evaluate the efficacy and mechanistic rationale for combining mTOR and WEE1 inhibition as a potential therapy for lung cancers harboring KRAS mutations. Experimental Design: We investigated the synergistic effect of combining mTOR and WEE1 inhibitors on cell viability, apoptosis, and DNA damage repair response using a panel of human KRAS- mutant and wild type NSCLC cell lines and patient-derived xenograft cell lines. Murine autochthonous and human transplant models were used to test the therapeutic efficacy and pharmacodynamic effects of dual treatment. Results: We demonstrate that combined inhibition of mTOR and WEE1 induced potent synergistic cytotoxic effects selectively in KRAS -mutant NSCLC cell lines, delayed human tumor xenograft growth and caused tumor regression in a murine lung adenocarcinoma model. Mechanistically, we show that inhibition of mTOR potentiates WEE1 inhibition by abrogating compensatory activation of DNA repair, exacerbating DNA damage in KRAS -mutant NSCLC, and that this effect is due in part to reduction in cyclin D1. Conclusions: These findings demonstrate that compromised DNA repair underlies the observed potent synergy of WEE1 and mTOR inhibition and support clinical evaluation of this dual therapy for patients with KRAS -mutant lung cancers. Clin Cancer Res; 23(22); 6993-7005. ©2017 AACR .