Cooperation between the Hippo and MAPK pathway activation drives acquired resistance to TEAD inhibition IV

TEAD transcription factors (TEAD1-4) serve as the primary effectors of the Hippo signaling pathway in various cancers. There has been significant progress in the development of therapeutic strategies aimed at disrupting the interaction of TEAD with its coactivators YAP/TAZ. However, targeted therapy leads to the emergence of resistance which poses a barrier to achieving complete cures. Currently, the underlying mechanism of resistance to TEAD inhibition in cancers remains unexplored. We uncover that upregulation of the AP-1 transcription factors, along with restored YAP/TEAD activity, drives resistance to GNE-7883, a pan-TEAD and allosteric TEAD inhibitor. Acute GNE-7883 treatment abrogates YAP binding and attenuates FOSL1 activity but compensation by increased MAPK pathway activity remains insufficient for cell survival. In contrast, TEAD inhibitor resistant cells are able to restore YAP and TEAD occupancy and acquire additional FOSL1 binding sites, leading to increased chromatin accessibility at AP-1 motifs. Resistant cells undergo transcriptional reprogramming to acquire a mesenchymal-like cell state and sustained MAPK activity. We uncover a dependence on the MAPK pathway in the TEAD inhibitor resistant cells, further highlighting the key role of MAPK pathway inhibitors, such as Cobimetinib and Belvarafenib to mitigate resistance mechanisms to TEAD inhibition in Hippo pathway dependent cancers. This study describes a clinically relevant interplay between the Hippo and MAPK pathway in cancers and offers a promising avenue to address TEAD inhibitor resistance in the clinic. Overall design: To investigate the mechanism involved in TEAD acquired resistance, we developed TEADi resistant cell lines. We then performed exome-sequencing of the parental (sensitive) cell line and the GNE7883-resistant clone (CL3).