Adjuvant Rezvilutamide in Combination With Androgen Deprivation Therapy in Androgen Receptor-positive, High-risk Salivary Duct Carcinoma

Inclusion Criteria: * Provision of signed and dated informed consent form * Stated willingness to comply with all study procedures and availability for the duration of the study * Histologically confirmed salivary duct carcinoma and stage III or IVa or IVb according to AJCC Cancer Staging Manual Eighth Edition * Completed SDC surgery, and adjuvant radiotherapy is planned or ongoing or has completed * Androgen receptor (AR) positive * White blood cell (WBC) ≥ 3.0 x 10\^9/L, Neutrophil count≥ 1.5 x 10\^9/L, Platelet count (PLT) ≥ 75 x 10\^9/L, Haemoglobin (Hb) ≥ 90 g/L * Serum creatinine (Cr) \< 1.5 x upper limit of normal(ULN) or creatinine clearance ≥ 50 ml/min. * Total bilirubin (TBIL) \< 1.5 x ULN, AST\< 2.5 x ULN, and ALT\< 2.5 x ULN * Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2, and ability to take oral medication * For females of reproductive potential: use of highly effective contraception for at least 1 month prior to screening and agreement to use such a method during study participation and for an additional 1 year after the end of study intervention administration * For males of reproductive potential: use of condoms or other methods to ensure effective contraception with partner Exclusion Criteria: * Received prior anti-AR pathway therapy * Treatment with another investigational drug or chemotherapy within 6 months * History of hypothalamus or pituitary dysfunction * History of seizure * Clinically uncontrolled diseases, such as septic shock, uncontrolled hypertension, unstable angina, New York Heart Association (NYHA) class III or IV heart disease, clinically unstable arrhythmia, myocardial infarction (in the past 6 months) * Previous cancer except skin cancer rather than malignant melanoma or any cancer curatively treated \> 5 years prior to study entry * Pregnancy or lactation