YES1 amplification as a primary driver of lung tumorigenesis and YES1/YAP1 amplifications as mediators of acquired resistance (AR) to ALK and EGFR tyrosine kinase inhibitors (TKIs).

Abstract

e21591 Background: Our previous work identified YES1 amplification as a mechanism of AR to EGFR TKIs. The current study investigates the potential role of YES1 amplification as a primary driver of tumorigenesis and of YES1/YAP1 amplifications as mediators of AR to ALK and EGFR TKIs. Methods: Models of ectopic expression were established and characterized for YES1 and YAP1 in human bronchial epithelial cells (HBECs) and ALK fusion-positive ( ALK+) and EGFR-mutant ( EGFRm) lung adenocarcinoma (LUAD) cell lines. MSK-IMPACT data for all LUAD cases and for ALK and EGFR TKI AR cases were surveyed for YES1 and YAP1 amplification. Results: YES1 was found to be amplified in 0.5% of all LUAD cases currently in the MSK-IMPACT database. To demonstrate its potential as a primary driver of tumorigenesis, YES1 was inducibly expressed in HBECs and shown to promote EGF-independent growth, focus formation, and increases in proliferation rate and sensitivity to Src family kinase (SFK) TKIs. Consistent with these findings, a partial response by RECIST criteria to third-line dasatinib was observed for a patient with stage IV LUAD in which MSK-IMPACT detected YES1 amplification and no established primary driver alteration. In models of AR, overexpression of either YES1 or YAP1 in multiple ALK+ and EGFRm cell lines conferred resistance to ALK and EGFR TKIs. Sensitivity to ALK or EGFR TKIs was partially recovered in YES1-overexpressing cells lines by siRNA-mediated gene knockdown of YAP1, and was restored in YAP1-overexpressing cells lines by knockdown of YES1 or mutation of the YES1-phosphorylation site on YAP1. ALK + or EGFR m cells overexpressing either YES1 or YAP1 were sensitive to dual inhibition of the primary driver and SFKs with single-agent repotrectinib or dasatinib, respectively. In contrast, treatment of YAP1-overexpressing ALK+ H3122 cells with alectinib induced changes in morphology and gene expression consistent with epithelial-to-mesenchymal transition (EMT) and rendered the cells insensitive to repotrectinib. Similar resistance to dual inhibition was seen in other YAP1-overexpressing cell lines after treatment with only ALK or EGFR blockade. To date, one LUAD case each of EGFR and ALK TKI AR has been found through MSK-IMPACT™ to be associated with YAP1 amplification. Conclusions: SFK inhibition can potentially be exploited to therapeutically target YES1 amplification as a primary driver in tumorigenesis and YES1/YAP1 amplifications as mediators of AR to ALK and EGFR TKIs.