PSMA-Guided Surgery and Tissue-Resident T-Cell Profiling in Node-Positive Prostate Cancer

This exploratory mechanistic study investigates tissue-resident bystander T cells in node-positive prostate cancer and the feasibility of using their molecular and functional features to inform personalized immunotherapeutic strategies. All participants undergo the same study pathway. On Day 0, gallium-68 PSMA-11 is administered intravenously (approximately 1.8-2.8 MBq/kg; standard activity approximately 160 MBq). PET/CT is performed approximately 60 minutes after tracer administration. Robot-assisted PSMA-radioguided surgery is then performed 4-8 hours after injection using a drop-in gamma probe. A positive intraoperative finding is defined as a count rate at least twice the background reference. PSMA-positive lesions are excised, followed by anatomically defined extended pelvic lymph-node dissection and Retzius-sparing robot-assisted radical prostatectomy. Fresh primary tumor, metastatic lymph-node tissue, FFPE tissue, and matched peripheral blood are collected. The first six participants are used primarily to optimize tissue acquisition and molecular workflows. The subsequent six participants expand the patient-derived tumor fragment platform and ex vivo immunological testing. Molecular analyses include scRNA-seq, scCITE-seq, scTCR-seq, bulk TCR sequencing, functional stimulation with common viral peptide pools, cytokine/chemokine assays, and spatial profiling. Functional bystander tissue-resident T cells are defined using integrated evidence of tissue detection, a resident/non-naive phenotype, ex vivo activation or proliferation after pathogen-derived peptide stimulation, and TCR clonotype identification. Participants are followed at Day 28 and Day 84 for laboratory tests, adverse events, perioperative outcomes, pathology, and postoperative data. The study is hypothesis-generating and is not powered for confirmatory clinical efficacy testing.