Discovery of a Highly Potent, N-terminal Domain-targeting degrader of AR-FL/AR-V7 for the treatment of Prostate Cancer

The clinical development of PROTACs targeting the androgen receptor (AR) for degradation has made significant progress. However, effective treatments for metastatic prostate cancers containing the androgen receptor splice variant 7 (AR-V7), a constitutively active mutant without the ligand-binding domain (LBD), are still lacking. Here, we reported the identification of a highly potent, noncovalent PROTAC targeting the N-terminal domain (NTD) of AR, NP18, which is developed from the covalent AR-NTD antagonist EPI-002, and effectively degrades both AR-FL and AR-V7 in 22Rv1 cells (DC₅₀: 18 and 26 nM respectively). Mechanistically, NP18 interacts with the N-terminal domain (NTD) of both full-length AR (AR-FL) and splice variant 7 (AR-V7), leading to their selective and proteasomal degradation. Importantly, NP18 exhibited remarkably superior antitumor activity in both 22Rv1 xenograft and patient-derived xenograft (PDX) models than EPI-002. Taken together, these findings highlight NP18 as a promising candidate to counteract AR splice variant-driven resistance.