This study is to evaluate safety, tolerability pharmacokinetics and efficacy of MDV3100 after oral administration to patients with castration-resistant prostate cancer.

This is a Phase1/2, open-label, uncontrolled study, involving Dose-Escalation Cohorts, where dose will be escalated to next dose with the safety, tolerability, and PK being evaluated in metastatic castration-resistant prostate cancer (mCRPC) patients and an Expansion Cohort, where the efficacy, safety, and PK of MDV3100 in post-chemo mCRPC patients will be evaluated. After evaluation of the safety and tolerability in Dose-Escalation Cohorts, additional patients are included in Expansion Cohort.

Inclusion Criteria:

• Histologically or cytologically confirmed adenocarcinoma of the prostate
• Ongoing androgen deprivation therapy with a GnRH analogue or a bilateral orchiectomy
• Progressive disease after prior androgen deprivation therapy (medical or surgical castration)
• For Expansion Cohort, the patient has no more than two prior chemotherapy regimens with at least one regimen containing docetaxel
• For Expansion Cohort, the patient must have measurable lesions by RECIST

Exclusion Criteria:

• Metastases in the brain
• History of another malignancy except for adenocarcinoma of the prostate within the previous 5 years
• Use of bicalutamide within 6 weeks prior to study
• Radiation therapy within 12 weeks prior to study
• Evidence of serious drug hypersensitivity

Access to anonymized individual participant level data will not be provided for this trial. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.