The sponsor's R&D strategy is adjusted.

The aim of this trial is to evaluate SHR3680 combined with SHR3162 and SHR3680 single drug to improve Metastatic Castration Resistant Prostate Cancer Patients whether the patient's overall survival (OS) is superior to placebo.

This is a multicenter, randomized , double-blind Phase II trial and the aim of this trial is to evaluate SHR3680 combined with SHR3162 and SHR3680 single drug to improve Metastatic Castration Resistant Prostate Cancer Patients Previously Treated With Abiraterone and Docetaxel whether the patient's overall survival (OS) is superior to placebo. The Stage I part is a dose-escalation and -expansion study. Approximately 18~24 patients in Stage I will receive fixed-dose of orally SHR3680 and only one of two dose levels of orally SHR3162. The Primary endpoints of the Stage I are incidence of adverse events(AE) and recommended phase 2 dose(RP2D). The Stage II part is a randomized , double-blind study. Approximately 90~120 patients in Stage II will receive SHR3162 combined with SHR3680, in which one fixed-dose levels of SHR3162 will be selected based on the result of the Stage I.The Primary endpoint of the Stage II is overall survival(OS).

Inclusion Criteria:

1. Histologically or cytologically confirmed prostate cancer; does not suggest neuroendocrine or small cell characteristics
2. Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) of 0 or 1;
3. Radiographic evidence of metastasis;
4. Sustained therapy of luteinizing hormone-releasing hormone analogue(LHRHA)or received bilateral orchiectomy; patients who did not receive bilateral orchiectomy are willing to receive sustained therapy of LHRHA;
5. Evidence of prostate cancer progression under the sustained therapy of LHRHA or bilateral orchiectomy;
6. Adequate hepatic, renal, heart, and hematological functions;
7. Patients have given voluntary written informed consent before performance of any study-related procedure not part of normal medical care,with the understanding that consent may be withdrawn by the patient at any time without prejudice to future medical care.
8. Patient has been treated with Abiraterone and treatment failed（Treatment failure is defined as the progression of disease during treatment）
9. Patient has been treated with Docetaxel and treatment failed or can not tolerate docetaxel chemotherapy or patients who are not suitable for docetaxel treatment at the time of screening.

Exclusion Criteria:

1. Have received any anti-tumor therapy in the past 4 weeks,including radiotherapy, chemotherapy, operation, targeted therapy, immuntherapy, and endocrinotherapy;
2. Planned to initiate any other anti-tumor therapies during the study;
3. Unable to swallow, chronic diarrhea and intestinal obstruction, or the presence of a variety of other factors that affect drug use and absorption;
4. Clinically significant cardiovascular diseases;
5. History of seizure or certain conditions that may predispose to seizure;
6. Severe concurrent disease and infection that, in the judgment of the investigator, would make the patient inappropriate for enrollment.