UT-155

UT-155 is a selective and potent androgen receptor (AR) antagonist, with a K_i of 267 nM for UT-155 binding to AR-LBD. IC50 & Target: Ki: 267 nM (AR-LBD)^[1]. In Vitro: UT-155 binds to the AR-LBD at K_i of 267 nM. UT-155 potently inhibits the R1881-induced wildtype AR transactivation with 6-10-fold higher potency than enzalutamide. While UT-155 antagonizes both wildtype and mutant ARs comparably, enzalutamide is weaker by two fold with the W742L mutant AR relative to the wild type AR. Treatment of LNCaP cells with UT-155 inhibits 0.1 nM R1881-induced PSA and FKBP5 gene expression between 10 and 100 nM with 5-10-fold better potency than enzalutamide^[1]. In Vivo: Consistent with the anti-proliferative effects in vitro, UT-155 significantly inhibits the growth of 22RV1 xenograft by 53%, while, as expected, enzalutamide has no effect on the growth of the 22RV1 tumors. Tumor weights and PSA and the expression of AR and AR-SV are significantly lower in UT-155-treated animals^[1].