Notch3-dependent β-catenin signaling mediates EGFR TKI drug persistence in EGFR mutant NSCLC

EGFR tyrosine kinase inhibitors cause dramatic responses in EGFR-mutant lung cancer, but resistance universally develops. The involvement of beta-catenin in EGFR TKI resistance has been previously reported, however, the precise mechanism by which beta-catenin activation contributes to EGFR TKI resistance is not clear. Here, we show that EGFR inhibition results in the activation of beta-catenin signaling in a Notch3-dependent manner, which facilitates the survival of a subset of cells that we call "adaptive persisters". We previously reported that EGFR-TKI treatment rapidly activates Notch3, and here we describe the physical association of Notch3 with beta-catenin, leading to increased stability and activation of beta-catenin. We demonstrate that the combination of EGFR-TKI and a beta-catenin inhibitor inhibits the development of these adaptive persisters, decreases tumor burden, improves recurrence free survival, and overall survival in xenograft models. These results supports combined EGFR-TKI and beta-catenin inhibition in patients with EGFR mutant lung cancer.