It was recently announced that the Finnish drugmaker Orion Corporation and Bayer Pharmaceuticals have entered an agreement to jointly develop Orion’s ODM-201, an oral, androgen receptor inhibitor. Bayer and Orion plan to jointly start the clinical Phase III program in 2014 to further evaluate the efficacy and safety of ODM-201 in patients with non-metastatic castration (hormone)-resistant prostate cancer. These patients are at high risk of developing metastatic disease and can be identified due to rapid Prostate Specific Antigen (PSA) increases. Phase II clinical studies of ODM-201 demonstrated it to be efficacious and well-tolerated. Eighty-six percent of patients who had not received earlier chemotherapy or abiraterone (Zytiga) experienced a greater than 50% PSA decrease at week 12 on a dose level of 700 mg twice a day. ODM-201 disrupts a tumor cell’s ability to use testosterone by binding with high affinity to the androgen (testosterone) receptor (AR) protein on cells, thereby inhibiting its cellular function. The AR normally binds to testosterone (which fuels prostate cancer) inside the cell and ushers it into the cell nucleus where it enhances cell growth. ODM-201 has similar activity to the anti-androgen drug enzalutamide.