Phase II Dutasteride in Combination With CAB vs CAB in SDC

Inclusion Criteria: * Pathologically/histologically proven diagnosis of (incurable) AR+ R/M salivary duct carcinoma * AR positive diseases (strong expression in at least 1% of nuclei of neoplastic cells based on central IHC review) * Measurable disease per RECIST version 1.1 at baseline. Appendix II. * Age ≥ 18 years * Written informed consent must be given according to national/local regulation * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 (Appendix III). * Adequate bone marrow function: * WBC ≥ 3.5/10\^9 /L * Absolute neutrophil count (ANC) ≥ 1.5x10\^9/L * Hemoglobin ≥ 6.20 mmol/L * Platelet count ≥ 100x10\^9/L * Adequate liver function: * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 times upper limit of normal (ULN) OR ≤ 5.0 times ULN for patients with liver metastases * Bilirubin ≤ 1.5 times ULN. For patients known with Gilbert's Syndrome ≤ 3.0 times ULN is permitted. * Adequate renal function: * Serum creatinine level ≤ 1.5 times ULN or calculated creatinine clearance ≥ 30 mL/min based on CKD-EPI-GFR * Adequate cardiac function Exclusion Criteria: * Patients with history of allergic reactions attributed to compounds of similar chemical or biological composition to goserelin, bicalutamide or dutasteride * Patients with peanut or soy allergy (dutasteride capsules contain lecithin which may contain soy oil) * Patients who do not have adequate swallowing capacity * Patients familiar with Long QT-syndrome (LQTS) * Patients (M/F) with reproductive potential not implementing adequate contraceptive measures * Patients that are pregnant or lactating * Patients with uncontrolled illness including: * Cardiovascular disorders, including symptomatic congestive heart failure, unstable angina pectoris, or serious cardiac arrhythmias * Uncontrolled hypertension (defined as sustained systolic BP \> 160 mm Hg, or diastolic BP \> 100 mm Hg. Unless evidence of white-coat hypertension) * Stroke (including TIA), myocardial infarction, or other ischemic event within 6 months before inclusion * Serious active infections * Patients undergoing concomitant treatments including: * Concomitant (or within 4 weeks before inclusion) administration of any other experimental drug under investigation * Concomitant (or within 6 months before inclusion) administration of any 5-alpha reductase inhibitor, i.e. dutasteride or finasteride * Concurrent treatment with any other anti-cancer therapy within the last 4 weeks before inclusion * Curative radiation therapy within the last 4 weeks before inclusion or palliative radiation therapy 1 week before start of study * Any condition which, in the opinion of the investigator, would preclude participation in this clinical study