Novel Trifluoromethylated Enobosarm Analogues with Potent Antiandrogenic Activity In Vitro and Tissue Selectivity In Vivo

Abstract

Prostate cancer often develops antiandrogen resistance, possibly via androgen receptor (AR) mutations, which change antagonists to agonists. Novel therapies with increased anticancer activity, while overcoming current drug resistance are urgently needed. Enobosarm has anabolic effects on muscle and bone while having no effect on the prostate. Here, we describe the activity of novel chemically modified enobosarm analogues. The rational addition of -trifluoromethyl groups into ring B of enobosarm, profoundly modified their activity, pharmacokinetic and tissue distribution profiles. These chemical structural modifications resulted in an improved AR binding affinity-by increasing the molecular occupational volume near helix 12 of AR., the analogues SK33 and SK51 showed very potent antiandrogenic activity, monitored using LNCaP/AR-Luciferase cells where growth, PSA and luciferase activity were used as AR activity measurements. These compounds were 10-fold more potent than bicalutamide and 100-fold more potent than enobosarm within the LNCaP model. These compounds were also active in LNCaP/BicR cells with acquired bicalutamide resistance. , using the AR-Luc reporter mice, these drugs showed potent AR inhibitory activity in the prostate and other AR-expressing tissues, e.g., testes, seminal vesicles, and brain. These compounds do not inhibit AR activity in the skeletal muscle, and spleen, thus indicating a selective tissue inhibitory profile. These compounds were also active in the - deletion model. SK33 and SK51 have significantly different and enhanced activity profiles compared with enobosarm and are ideal candidates for further development for prostate cancer therapy with potentially fewer side effects. .

Discovery of deshydroxy bicalutamide derivatives as androgen receptor antagonists

“…[10][11][12] Previously, we have found that the introduction of 3,5-bis-trifluoromethyl (3,5-bis-CF3) substituents into ring B of bicalutamide, enobosarm and umbelliferone derivatives, has profoundly modified their anti-proliferative activity, pharmacokinetic and tissue distribution profiles by providing the geometric bulk needed to keep ring B towards Helix 12 while keeping the crucial interactions of the nitrile/nitro group of ring A with Arg 752. [13][14][15] Noting that both flutamide and darolutamide (ODM-201) are lacking the linker OH group, Figure 1, in this work we studied whether the central hydroxyl group of bicalutamide is necessary for maintaining the anti-androgen activity and if the successive increase in the bulk size of ring B substituents (from 4-F  4-CF3  3,5-bis-CF3) would compensate for the smaller size of the deshydroxy linker (lacking the central OH group). We used four different variations of aromatic ring A ( Figure 3); all containing the necessary 4-CN or 4-NO2 for the interaction with Arg 752 in addition to either 2-CF3 or 3-CF3 substituent to understand better the structure activity relationship.…”

AR mRNA stability is increased with AR-antagonist resistance via 3′UTR variants

“…Recently, we generated bicalutamide and enzalutamide-resistant clones of the LNCaP and VCaP cell lines, as tools for screening novel AR-antagonist compounds (10, 11). The VCaP BicR / EnzR -resistant clones showed resistance to both bicalutamide and enzalutamide – showing cytostatic effects at high doses.…”

Enzalutamide, a prostate cancer therapeutic, downregulates TMPRSS2 in lung and reduces cellular entry of SARS-CoV-2

“…Pten loxp/loxp ;Pb-Cre4 mice (The Jackson Laboratory, Bar Harbour, ME, USA), which have prostate-speci c PTEN deletion 62 , were treated with 50 mg/kg Enzalutamide (in 5% DMSO +1% CMC +0.1% P80 oral gavage) or vehicle control every day for three days. All work was carried out in accordance with the provisions of the Animals (Scienti c Procedures) Act 1986 of the United Kingdom.…”