Oligometastatic Prostate Cancer (OMPC)

The purpose of this study is to evaluate the efficacy and safety of lutetium (177Lu) vipivotide tetraxetan (AAA617) in participants with oligometastatic prostate cancer (OMPC) progressing after definitive therapy to their primary tumor. The data generated from this study will provide evidence for the treatment of AAA617 in early-stage prostate cancer patients to control recurrent tumor from progressing to fatal metastatic disease while preserving quality of life by delaying treatment with androgen deprivation therapy (ADT).

The investigators propose redefining this concept by focusing on volume rather than the number of metastases. To achieve this, the investigators aim to determine the Maximum Tolerated Volume (MTV) of metastatic lesions treatable with SRT (Stereotaxic radiotherapy) in a phase 1 study. In this study, the investigators will recruit patients with high-volume metastatic disease in bones or lymph nodes and progressively irradiate a volume-escalated subset of the total lesions. The selection will prioritize lesions at higher risk of causing pain or complications, such as fractures, spinal compression, or vascular compression. The investigators hypothesis is that SRT targeting multiple metastases (with a total volume ≤ MTV) will extend the duration without refractory pain and/or tumor-related complications in patients with castration-resistant and chemo-refractory prostate cancer.

The goal of this clinical trial is to learn whether an experimental vaccine called pTVG-HP ("vaccine" or "DNA vaccine"), combined with a drug called nivolumab can increase the cancer-fighting ability of a person's immune cells. The main question it aims to answer is whether the combination of medicines can get rid of metastatic tumors in participants with non-castrate, recurrent, oligometastatic prostate cancer. Participants will undergo: * Treatment with pTVG-HP * Treatment with Nivolumab * Radiation Therapy