Cell experiment:

To study the antiproliferative properties of Darolutamide and ORM-15341, the VCaP cell line originally derived from a bone metastasis of a CRPC patient is used. The VCaP cell line is characterized with endogenous AR gene amplification and AR overexpression30, typical for CRPC. VCaP cells are cultured in RPMI-1640 medium and supplemented with 10% fetal bovine serum (FBS), 100 UI/mL penicillin, 100 μ g/mL streptomycin, and 4 mM VCaP[1].

Animal experiment:

To elucidate the in vivo efficacy of Darolutamide in a CRPC mouse model, castrated male nude mice with subcutaneously injected VCaP cells are treated orally with ODM-201 (50 mg/kg) once (qd) or twice daily (bid), or with enzalutamide (20 mg/kg, qd) for 37 days. The dose for enzalutamide is selected based on previously published studies9 and our pharmacokinetic (PK) analyses which reveales that in mice the systemic exposure (AUC0–24) for this dose of enzalutamide is 2.5 times higher than that for Darolutamide (50 mg/kg, bid). Moreover, enzalutamide exhibited a long plasma half-life (18.3 hours) while the half-life of Darolutamide in mice is not optimal (1.6 hours) supporting once daily dosing for enzalutamide and higher dose and more frequent dosing for ODM-201[1].

ODM-201 is a new-generation inhibitor of androgen receptor with Ki value of 11 nM [1].

Androgen receptor is a type of nuclear receptor that is activated by androgen and functions as a DNA-binding transcription factor that regulates gene expression. Activation of androgen receptor (AR) is crucial for prostate cancer growth [1].

ODM-201 is a high-affinity and potent androgen receptor antagonist. In competitive AR binding assays, ODM-201 exhibited Ki value of 11 nM. In AR-HEK293 cells stably expressing full-length human AR (hAR) and an androgen-responsive luciferase reporter gene construct, ODM-201 and its major metabolite ORM-15341 inhibited AR-mediated transactivation with IC50 values of 26 nM and 38 nM. In human U2-OS osteosarcoma cells expressing wtAR or mutant AR(F876L), AR(W741L), or AR(T877A), ODM-201 and ORM-15341 also functioned as full antagonists. in AR overexpressing HS-HEK293 cells, ODM-201 inhibited the androgen-induced nuclear translocation of overexpressed AR. In the VCaP cell line with endogenous AR gene amplification and AR overexpression, ODM-201 inhibited androgen-induced cell proliferation with IC50 value of 230 nM.

In castrated male nude mice with subcutaneously injected VCaP cells, orally treatment with ODM-201 (50 mg/kg) once (qd) or twice daily (bid) for 37 days, ODM-201 showed a significant antitumor activity with both doses. There was no sign of treatment-related toxicities. In orthotopic VCaP tumor-bearing intact nude mice, ODM-201 (50 mg/kg, bid) significantly inhibited tumor growth but did not affect the testosterone levels in serum. ODM-201 couldn’t penetrate the blood-brain barrier [1].

Reference:
[1].Moilanen AM, Riikonen R, Oksala R, et al. Discovery of ODM-201, a new-generation androgen receptor inhibitor targeting resistance mechanisms to androgen signaling-directed prostate cancer therapies. Sci Rep, 2015, 5: 12007.