‣ All patients must meet the following criteria to be eligible for Phase 1 study participation:

• Males of age 18 years at the time of signing the informed consent form (ICF).

• Able to understand and voluntarily sign an informed consent document prior to any study-related assessments/procedures.

• Patients must have histological, pathological, and/or cytological confirmation of adenocarcinoma of the prostate.

• Patients must have prior orchiectomy and/or ongoing androgen-deprivation therapy and a castrate level of serum testosterone.

• Patients must have progressed on prior line(s) of therapy.

• Patients must have progressive mCRPC defined as having demonstrated PSA progression on the prior regimen. PSA progression may have occurred with or without accompanying radiographic progression.

• Eastern Cooperative Oncology Group (ECOG) performance status 0-1.

• Life expectancy of at least 3 months.

• Adequate hematological, renal, and hepatic function.

⁃ Able to swallow an oral medication.

⁃ Willing and able to adhere to the study visit schedule and other protocol requirements.

⁃ Patients on a stable bisphosphonate or denosumab regimen for 30 days prior to enrollment are eligible.