Phase 2 Study of Neoadjuvant PEMbrolizumab Before Radical PROstatectomy in High-risk Prostate Cancer Patients

This is a phase 2, open-label, non-randomized, single-arm study in patients with high-risk PCa diagnosed with prostate biopsy and undergoing RP and ePLND. Pembrolizumab will be administered at the dose of 200 mg intravenously, every 3 weeks, for a total of 3 cycles prior to RP and ePLND. Local, nodal and systemic staging with prostate mpMRI, abdominal and chest CT, PSMA-PET/CT and bone scans will be performed before the administration of pembrolizumab. Surgery will be planned at the time of study inclusion to be done within 3 weeks of the last dose of study drug (screening: 3 weeks; cycle 1 followed by 3 weeks; cycle 2 followed by 3 weeks; cycle 3 followed by 3 weeks to surgery = 12 weeks from inclusion to surgery). Patients will receive 3 cycles of pembrolizumab at 200mg 3 weekly prior to RP and ePLND. Surgery will take place within 3 weeks after the last dose of the study drug. After surgery, patients with the evidence of aggressive disease features (namely, pathologic grade group 4-5; pT3b-4 and/or LNI) will be managed according to local guidelines (adjuvant radiotherapy with or without ADT will be allowed). Further Anti PD-1 therapy will not be given post-operatively. PD-L1 status will be retrospectively assessed on both tumour cells and immune cells in tissue specimens from for all patients enrolled in the study.