To assess the feasibility and safety of Maximal cytoreductive therapies in patients with de novo mCSPC who achieve ≤10 oligopersistent metastases on PSMA PET CT after initial 3-month systemic treatment with apalutamide plus ADT. Maximal cytoreductive therapies consist of 1.cytoreductive radical prostatectomy with/without PLND guided by post-treatment PET 2.metastasis-directed therapy with radiation guided by post-treatment oligopersistent metastases. All patients receive continuous systemic treatment with apalutamide plus ADT.

Inclusion Criteria:

1. Able to understand and willing to sign the informed consent;
2. Aged ≥18 years;
3. Histologically or cytologically confirmed prostate adenocarcinoma (primary small cell carcinoma or signet-ring cell carcinoma of the prostate are not allowed, however adenocarcinoma with neuroendocrine differentiation accounting ≤10% is allowed);
4. Newly diagnosed prostate cancer (within 3 months prior to enrollment);
5. M1a/b disease with the presence of 1-10 visible metastases at diagnosis by conventional imagine including bone scan (ECT) and CT or MRI of the chest, abdomen, and pelvis;
6. With initial systemic treatment of apalutamide plus ADT and willing and expected to comply with treatment and follow up schedule [No more than 2-month systemic treatment before enrollment (including ADT and ADT combined with short-term first-generation anti-androgen therapy (flutamide or bicalutamide); To maximize enrollment, patients who had started apalutamide plus ADT before enrollment are allowed into the study provided that they are otherwise eligible and therapy was initiated no longer than 2 months before enrollment];
7. Fit to undergo cytoreductive radical prostatectomy and radiotherapy to the visible sites of metastases;
8. ECOG PS score is 0-1;
9. Adequate organ function;
10. Life expectancy ≥ 12 months.

Exclusion Criteria:

1. History of allergies, hypersensitivity, or intolerance to any drug used in the study;

2. Had the contraindications or is intolerant to cRP or RT;

3. Had any visceral metastases (brain, liver, lung etc.) on screening conventional imaging (bone scans, CT or MRI);

4. Prior Received any of the following treatments for primary and metastatic prostate cancer;

   1. >2-month ADT or first-generation antiandrogens (bicalutamide, flutamide etc.);
   2. Any other novel hormonal therapies (enzalutamide, darolutamide, abiraterone etc.) except ≤ 2-month apalutamide plus ADT listed in inclusion criteria;
   3. Any chemotherapy;
   4. local treatment or metastatic treatment for primary prostate cancer or metastases;
   5. Any immunotherapy (PD-L1 etc.), target therapy (PARPi etc), etc;

5. History of seizure or known condition that may predispose to seizure;

6. History of major surgery 4 weeks before enrollment;

7. Had major cardiovascular and cerebrovascular diseases within 6 months prior to the start of the study;

8. Any condition that could interfere with drug absorption(e.g. unable to swallow, chronic diarrhea etc. );

9. Conditions of active infection;

10. History of previous or current malignant disease, except for curatively treated tumors cured for more than 3 years;

11. Patients who is currently undergoing other trials;

12. Unwilling or difficult to cooperate with treatment and follow-up visit;

13. Other sever conditions which could interfere with trial safety or results judged by the investigator.