Specific Inhibition of NOTCH2 Signaling in Bladder Cancer

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The prognosis of patients with metastatic bladder cancer (BC) is poor. Individual targeted therapies seem to be a putative strategy in order to extend therapeutic options beyond systemic chemo- and immunotherapy. The group of Dr. Peter Black identified NOTCH2 (N2) as an oncogene in urothelial BC and both tumor growth and metastasis were suppressed using a specific N2-targeting antibody in an orthotopic xenograft mouse model. Furthermore, N2 RNA overexpression was correlated with poor survival in The Cancer Genome Atlas 2017 cohort in BC. Intriguingly, NOTCH1 (N1) signaling was demonstrated to play a tumor-suppressive role in BC. Two druggable sites on the N2 receptor were identified by Dr. Black’s group, which were both significantly dissimilar to the N1 molecular receptor configuration. Therefore, we intend to conduct a project aimed to identify and evaluate novel highly selective N2 inhibitors that do not interfere with other Notch receptors in BC.We will perform a structure-based virtual screening with ~10 million compounds from publicly available databases such as ZINC15 and ChEMBL, utilize computer-aided drug design programs and chemoinformatic techniques to identify the most promising small molecular compounds for selective N2 inhibition. In the next step, we will select compounds by in vitro screening of N2 inhibition using a Notch-specific responsive plasmid in a cell-based luciferase assay. Compound stability and metabolic degradation will be assessed in a microsomal instability assay. Antineoplastic effects of N2 inhibitors will be further analysed in BC cell lines, utilizing cell growth, cell-cycle progression, migration and invasion in vitro assays. Dosing parameters, degradation of compounds and toxicity as well as impact on tumor growth and metastasis will be assessed in an orthotopic BC xenograft mouse model in vivo.Importantly, there are no therapies targeting Notch signaling approved for patient care so far. A small molecule N2 specific inhibitor might bypass not only common side effects seen in unspecific pan-Notch inhibitors, but also disadvantages of monoclonal antibodies like antibody degradation and low tissue penetration. Taken together, our translational approach might lead to a highly specific small molecule N2 inhibitor with the capability to offer novel therapeutic options for patients with metastatic BC.