Comparing a 6-month vs Long-term Course of Rezvilutamide With ADT Plus Chemotherapy in mHSPC

Inclusion Criteria:

• Inclusion criteria:

1. Age ≥ 18 years, male.
2. Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1.
3. Histologically or cytologically confirmed prostate adenocarcinoma withoutevidence of neuroendocrine or small cell features.
4. High tumor burden, defined as having at least one of the following conditions: 1)Bone scan showing ≥4 bone metastatic lesions (with at least one site outside thepelvis or spine). 2) CT/MRI revealing visceral metastatic lesions (excludinglymph nodes).
5. Planned to receive or maintain androgen deprivation therapy (ADT) during thestudy period, either by continuous LHRHa treatment or previous bilateralorchiectomy (surgical castration), concurrently with 6 cycles of docetaxelchemotherapy.
6. Organ function levels must meet the following requirements:

• Absolute neutrophil count (ANC) ≥ 1.5 × 10^9/L.
• Platelets (PLT) ≥ 100 × 10^9/L.
• Hemoglobin (Hb) ≥ 90 g/L.
• Total bilirubin (TBIL) ≤ 1.5 × upper limit of normal (ULN).
• Alanine aminotransferase (ALT) ≤ 2.5 × ULN.
• Aspartate aminotransferase (AST) ≤ 2.5 × ULN.
• Blood urea nitrogen (BUN) (or urea) and creatinine (Cr) ≤ 1.5 × ULN.
• Left ventricular ejection fraction (LVEF) ≥ 50%.

7. Judged by the investigator to be able to comply with the trial protocol.
8. Voluntarily participate in the clinical trial, understand the study procedures,and have signed the informed consent form.

Exclusion Criteria:

1. Prior treatment with ADT, chemotherapy, surgery, external beam radiation therapy,brachytherapy, radiopharmaceuticals, or investigational local therapies for prostatepain. However, the following cases are allowed for inclusion:

• Up to 3 months of ADT (medical or surgical castration) with or withoutantiandrogen therapy prior to Cycle 1 Day 1 (C1D1) without evidence ofradiographic disease progression (based on RECIST 1.1 criteria) or clinicallysignificant PSA rise (defined as ≥50% increase from the lowest level afterreaching castration levels of serum testosterone) before C1D1.
• Transurethral prostatectomy or up to one course of palliative radiation therapyor surgery for symptomatic treatment of metastatic disease at least 4 weeks priorto C1D1. All adverse events related to these treatments must have improved to atleast Grade 1 (according to NCI-CTCAE v4.03) before starting study treatment.

2. Prior use or planned use of second-generation androgen receptor antagonists (such asenzalutamide, apalutamide, darolutamide), abiraterone acetate, or otherinvestigational drugs inhibiting testosterone synthesis for the treatment of prostatecancer during the study period.
3. Received the following treatments within 4 weeks before C1D1:

• 5-alpha-reductase inhibitors (e.g., finasteride, dutasteride).
• Estrogens, progestins, androgens, systemic corticosteroids (except for temporaryuse for allergic purposes).
• Known herbal medicines with anti-prostate cancer or PSA-lowering effects (e.g.,saw palmetto).
• Participation in other clinical trials involving investigational treatments.

4. Confirmed brain tumor lesions on imaging.
5. Planned to receive any other anticancer treatment during the trial.
6. Known allergy or hypersensitivity to apalutamide, ADT, or chemotherapy components.
7. Presence of conditions that impede swallowing, chronic diarrhea, intestinalobstruction, or other factors affecting drug intake and absorption.
8. History of seizures or occurrence of conditions that can induce seizures within 12months before C1D1 (including transient ischemic attack, stroke, traumatic braininjury with altered consciousness requiring hospitalization).
9. Presence of active cardiac diseases within 6 months before C1D1, includingsevere/unstable angina, myocardial infarction, symptomatic congestive heart failure,and ventricular arrhythmias requiring medication.
10. Diagnosis of any other malignancy within 5 years before C1D1, except for completelyresolved in situ cancer or malignancies with slow progression as determined by theinvestigator.
11. Active HBV or HCV infection (HBV viral load ≥ 10,000 copies/mL, HCV viral load ≥ 1,000copies/mL).
12. History of immunodeficiency (including positive HIV test) or organ transplantation.
13. Unwillingness to use effective contraception during the entire study treatment periodand for 30 days after the last dose.
14. Judged by the investigator to have conditions that pose a serious risk to patientsafety, may confound study results, or may affect the patient's ability to completethe study (such as poorly controlled hypertension, severe diabetes, neurological orpsychiatric diseases, etc.), or any other relevant circumstances.