Discovery Of Yap-Tead Protein-Protein Interaction (Ppi) Inhibitors For Cancer Therapy

The Hippo pathway is emerging as a critical player in several processes involved in cancer progression, including cell proliferation and EMT. YAP mediates the downstream effects of Hippo signaling, and high nuclear expression of YAP has been documented in many tumors types. YAP translocates to the nucleus, binds to TEAD transcription factor and drives the expression of growth factors, including CTGF, Cyr61 and surviving, suggesting that therapies targeting YAP-TEAD interaction are likely to have clinical impact for the treatment of cancer patients. However, due to the challenging nature of protein-protein interactions, a potent inhibitor that surpasses the affinity of the YAP-TEAD interactions has not been developed. All the critical residues for the YAP-TEAD interaction belong to interface S3. In order to identify interface S3 binders able to disrupt the YAP-TEAD interaction, we started a drug discovery program based on combined FBS/HTS strategy. TEAD protein drugabbility was assessed by fragment screen using NMR and SPR technologies. This approach, supported by assigned HSQC protein NMR information, provided fragment hits which were used as starting points for the identification of more potent binders. We also designed an AlphaLisa assay to validate the ability of our compounds to disrupt the YAP-TEAD interaction. 240,000 compounds of our proprietary library were screened using AlphaLisa assay. Several hits in the μM range were identified and further confirmed using SPR. Successful chemistry optimization generated compounds showing inhibitory activity in the AlphaLisa assay at 50-100 nM for the best compounds. To confirm the validity of our inhibitors, we constructed plasmids encoding TEAD protein fused to Gal4 DNA-binding domain. We transfected HEK293 cells with these plasmids together with Gal4-driven luciferase reporter plasmid in the presence of YAP S127A/S397A. Our compounds showed marked inhibition of cell-based transactivation assay at 3-10 μM. In order to establish a panel of cancer cell lines whose proliferation and target gene expression were either dependent or independent of YAP/TEAD, we selected several cell lines based on their mutational status, YAP nuclear localization, and their proliferative response to a siRNA targeting either YAP or TEAD. Our data show that YAP-TEAD inhibitors block both cell proliferation and target gene expression only in YAP/TEAD-dependent cell lines. In conclusion, we have successfully demonstrated that YAP-TEAD PPI can be inhibited by small molecules, and our compounds show activity in cell-based assays. Medicinal chemistry optimization on various series is ongoing to improve potency and DMPK parameters for further in vivo evaluation in cancer xenograft models. Citation Format: Anne Soude, Martine Barth, Stephanie Bocart, Frederic Thoreau, Philippe Masson, Isabelle Braccini, Christian Montalbetti, Pierre Broqua, Claudia Fromond. Discovery of YAP-TEAD protein-protein interaction (PPI) inhibitors for cancer therapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 894.