Darolutamide (ODM-201) is a novel androgen receptor (AR) antagonist with a 
chemical structure distinctly different from currently approved AR antagonists 
that targets both wild-type and mutated ligand binding domain variants to 
inhibit AR nuclear translocation. Here, we evaluate the activity of darolutamide 
in enzalutamide-resistant castration resistant prostate cancer (CRPC) as well as 
in AR mutants detected in patients after treatment with enzalutamide, 
abiraterone, or bicalutamide. Darolutamide significantly inhibited cell growth 
and AR transcriptional activity in enzalutamide-resistant MR49F cells in vitro, 
and led to decreased tumor volume and serum prostate-specific antigen levels in 
vivo, prolonging survival in mice bearing enzalutamide-resistant MR49F 
xenografts. Moreover, darolutamide inhibited the transcriptional activity of AR 
mutants identified in the plasma of CRPC patients progressing on traditional 
therapies. In particular, darolutamide significantly inhibited the 
transcriptional activity of the F877L, H875Y/T878A, F877L/T878A, and the 
previously unreported T878G AR mutants, that transform enzalutamide into a 
partial agonist. In silico cheminformatics computer modeling provided atomic 
level insights confirming darolutamide antagonist effect in F877L and T878G AR 
mutants. In conclusion, our results provide a rationale for further clinical 
evaluation of darolutamide in enzalutamide-resistant CRPC, in particular in 
combination with circulating tumor DNA assays that detect AR mutants sensitive 
to darolutamide, in a precision oncology setting.
PATIENT SUMMARY: In this study we evaluated the novel drug darolutamide in 
preclinical models of prostate cancer. We found that darolutamide delays growth 
of enzalutamide-resistant prostate cancer, in particular in cells with mutated 
forms of the androgen receptor after previous treatment. Our data supports 
further evaluation of darolutamide in clinical trials.