TENDU Vaccine in Patients With Relapse After Primary Radical Prostatectomy

Inclusion Criteria: 1. Males ≥18 years of age 2. PSA rise \>0.2 ng/mL less than 18 months following radical prostatectomy (RP) and pathological ISUP Grade 4-5 (Gleason score \>7), or persisting PSA \>0.1 ng/mL six weeks after RP and short PSA-DT, eligible for salvage radiotherapy and short term androgen deprivation therapy 3. ECOG performance status 0 or 1 4. Adequate organ function as indicated by the following laboratory values: * White blood cell count ≥ 2,500/μL * Absolute neutrophil count ≥ 1,000/μL * Platelets ≥ 100,000/μL * Haemoglobin ≥ 9 g/dL or ≥ 5.6 mmol/L * Serum creatinine ≤ 1.5 x upper limit of normal (ULN) * Serum total bilirubin ≤ 1.5 x ULN or direct bilirubin ≤ ULN for patients with total bilirubin levels \> 1.5 ULN * AST and ALT ≤ 2.5 x ULN 5. Patients with potential to father children must use an acceptable contraceptive method 6. Written informed consent prior to any study-specific evaluations Exclusion Criteria: 1. History of hematologic or primary solid tumor malignancy other than prostate cancer with remission less than 3 years prior study enrolment. 2. Metastatic disease assessed by PSMA PET/CT 3. Hypersensitivity to the active substance or any of its excipients 4. Current use of androgen deprivation therapy or radiotherapy to the pelvis 5. Known history or any evidence of active, non-infectious pneumonitis 6. History of New York Heart Association class 3-4 congestive heart failure or history of myocardial infarction within 6 months of starting study treatment 7. Active autoimmune disease that has required systemic treatment in past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Patients with vitiligo or resolved childhood asthma/atopy would be an exception to this rule. 8. Active infection requiring systemic therapy 9. Diagnosis of immunodeficiency 10. Any use of immunosuppressive (cytotoxic chemotherapy, systemic steroids) or immunomodulating agents within 8 weeks of study entry. 11. Hepatitis B or Hepatitis C or Human Immunodeficiency Virus positive 12. Expected to require any other form of systemic or localized antineoplastic therapy during the study 13. Received any other investigational therapy within 4 weeks of the first dose of study treatment 14. Any medical, psychological, social or neurological condition that would make it difficult for the patient to participate in the study and comply with the study procedures, restrictions, and requirements