Lutetium-177-PSMA Radioligand Therapy in Advanced Salivary Gland Cancer Patients

Inclusion Criteria: * Patients must have the ability to provide written informed consent. * Patients must be ≥ 18 years of age. * Patients must have an ECOG performance status of 0 to 2. * Patients must have histological, pathological, and/or cytological confirmation of either adenoid cystic carcinoma or salivary duct carcinoma. * Patients must have incurable, local or regional recurrent or metastatic ACC or SDC. * Patients with ACC can only participate in case of objective growth in the last three months or complaints due to the disease. * Patients must have adequate organ function: * Sufficient bone marrow capacity as defined by: WBC count (white blood cell) ≥2.5x10\^9/L, PLT (platelet) count ≥100x10\^9/L, Hb ≥6 mmol/L, absolute neutrophil count (ANC) ≥1.5x10\^9/L * Adequate liver function as defined by:Total bilirubin ≤1.5 x ULN. For patients known with Gilbert's Syndrome ≤ 3 x ULN is permitted. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3.0 × ULN OR ≤5.0 × ULN for patients with liver metastases. * Adequate kidney function as defined by:serum creatinine ≤1.5 x ULN or creatinine clearance ≥ 50 mL/min * Patients must have measurable disease at baseline. Defined as ≥ 1 lesion ≥ 2 cm (long axis) that is present on baseline CT. * Patients must have a positive 68Ga-PSMA PET/CT scan, defined by at least one lesion ≥ 1.5 cm (long axis) with a ligand uptake above liver level. Exclusion Criteria: * Patients whom are pregnant or breast feeding. * Patients with reproductive potential not implementing adequate contraceptives measures. * Patients with known brain metastases or cranial epidural disease or intracardial metastases. * Patients with concurrent serious (as determined by the Principal Investigator) medical conditions, including, but not limited to, New York Heart Association class III or IV congestive heart failure, history of congenital prolonged QT syndrome, uncontrolled infection, active hepatitis B or C, or other significant co-morbid conditions that in the opinion of the investigator would impair study participation or cooperation. * Patients with urinary tract obstruction or marked hydronephrosis * Less than 4 weeks since last myelosuppressive therapy or other radionuclide therapy. * Concomitant cancer treatments