This study evaluates the tolerability, safety, pharmacokinetics and efficacy of SHR3680 in patients with metastatic castration-resistant prostate cancer (mCPRC). All participants will receive SHR3680.

Androgenic signaling plays a pivotal role in the development of prostate cancer. Androgen deprivation therapy is the mainstay treatment for this cancer in the metastatic setting, but the disease eventually develops to castration-resistant prostate cancer (CRPC) mainly due to the overexpression of androgen receptors (AR) and continued AR activation.

SHR3680 is a novel strong AR antagonist. By competitively binding to AR, SHR3680 inhibits androgen-mediated translocation of AR to the nucleus, binding of AR to Deoxyribonucleic acid (DNA), and finally the transcription of AR target genes, thus possibly resulting in a specific and strong anti-tumor effect on prostate cancer. Unlike first-generation AR antagonists (e.g. bicalutamide), which undergoes an antagonist-to-agonist switch to stimulate AR in the setting of AR overexpression in CRPC, SHR3680 is a full antagonist of AR and thus it is supposed to be more effective for the treatment of CRPC.

Inclusion Criteria:

• ECOG performance scale 0 - 1.
• Life expectancy of more than 6 months.
• Histologically or cytologic confirmed prostate adenocarcinoma without neuroendocrine differentiation or small cell features
• Ongoing androgen deprivation therapy with a gonadotropin releasing hormone (GnRH) analogue or orchiectomy
• Evidence of prostate cancer progression by radiographic or PSA criteria
• Radiological evidence of distant metastatic lesions
• Serum testosterone level < 1.7 nmol/L (50 ng/dL) at the screening visit
• Adequate hepatic, renal, heart, and hematologic functions (platelets > 80 × 10e9/L, neutrophil > 1.5 × 10e9/L, Hb >90 g/L,total bilirubin and creatinine within upper limit of normal(ULN), and serum transaminase≤1.5×the ULN).
• Signed and dated informed consent.Willingness and ability to comply with scheduled visits, treatment plans, laboratory tests, and other study procedure.

Exclusion Criteria:

• Treatment with androgen receptor antagonists, 5-alpha reductase inhibitors, estrogens, or chemotherapy within 4 weeks of enrollment or plans to initiate treatment with any of these drugs during the study
• Prior treatment with enzalutamide, abiraterone, or ketoconazole for prostate cancer
• History of seizure or any conditions that may predispose to seizure
• Concurrent or planned treatment with corticosteroids, medications known to have seizure potential, or herbal products known to decrease PSA levels
• Planned to initiate any other anti-tumor therapies during the study
• Less than 4 weeks from the last clinical trial
• Evidence of brain metastasis or primary tumors
• Clinically significant cardiovascular diseases
• Abuse of alcohol or drugs
• Severe concurrent disease, infection, or bone metastasis that, in the judgment of the investigator, would make the patient inappropriate for enrollment