Molecular characterization of next generation AR-NTD inhibitors

Background: Inhibition of the androgen receptor (AR) is mainstay treatment for advanced prostate cancer. While initially effective, disease ultimately progresses to metastatic castration-resistant cancer (mCRPC), which lethal. All current AR-targeted therapies directly or indirectly target ligand binding domain (LBD). We have developed EPI and sintokamide (SINT) compounds AR N-terminal (NTD), allowing sustained inhibition in context constitutively active AR-splice variants mutations often drive resistance therapies. Ralaniten acetate (EPI-506, NCT02606123) next generation EPI-7386 (NCT04421222) remain only AR-NTD inhibitors progressed clinical trials. Here we characterize molecular profile several compared against traditional AR-LBD antagonist enzalutamide (ENZA). Methods: LNCaP LN95 cells treated with EPI-002, EPI-7170 ENZA were subjected RNA-seq identify differences mechanisms action each class inhibitor. Data was validated using qPCR both vitro as well xenografts. Protein-protein interactions following drug identified RIME PLA. Cell cycle DNA damage response assayed flow cytometry western blot. Results: RNA-sequencing on AR-V7 driven EPI-7170, EPI-002 revealed ability two classes de-repress repressed genes. A subsequent assay demonstrated that preferentially inhibited AR/TBL1XR1 interaction, latter forming a part NCOR1 transcriptional repression complex. The most significantly deregulated pathways associated GSEA analysis involved cell (G2M pathway; FDR∼0.000, mitotic spindle; FDR = 0.003) FDR∼0.000). induced G2 arrest, while unaffected. Pathway from data also indicated superior their block repair ENZA, sensitized radiation treatment. Conclusions: clear between inhibitor inhibitors; terms AR-regulated gene expression, disruptions response. This work highlights potential combination utilize inhibitors. An ongoing trial currently investigating (NCT05075577). Conflict interest: Ownership: J.K.O., C.A.B., N.R.M., J.W., A.H.T., M.D.S are inventors technology licensed BC Cancer by ESSA Pharma Inc. M.D.S. C.A.B equity