ODM-201 (also known as BAY-1841788) is a non-steroidal antiandrogen, specifically, a full and high-affinity antagonist of the androgen receptor (AR), that is under development by Orion and Bayer HealthCare for the treatment of advanced, castration-resistant prostate cancer (CRPC). ODM-201 appears to negligibly cross the blood-brain-barrier. This is beneficial due to the reduced risk of seizures and other central side effects from off-target GABAA receptor inhibition that tends to occur in non-steroidal antiandrogens that are structurally similar to enzalutamide. Moreover, in accordance with its lack of central penetration, ODM-201 does not seem to increase testosterone levels in mice or humans, unlike other non-steroidal antiandrogens. Another advantage is that ODM-201 has been found to block the activity of all tested/well-known mutant ARs in prostate cancer, including the recently-identified clinically-relevant F876L mutation. ODM-201 has been studied in phase I and phase II clinical trials and has thus far been found to be effective and well-tolerated, with the most commonly reported side effects including fatigue, nausea, and diarrhea. No seizures have been observed.

ORM-15341 is an active main metabolite of ODM-201, which is structurally distinct from any known antiandrogens including the second-generation antiandrogens enzalutamide. ORM-15341 is a potent and full antagonist for human androgen receptor. It was shown, that in VCaP prostate cancer cells containing endogenous AR gene amplification and overexpressing AR, ORM-15341 inhibited cell proliferation more efficiently than enzalutamide or ARN-509.