Exploiting Heterogeneity in Hormone Therapy Response to Reveal Early Determinants of Drug Resistance in Advanced PCa

The goal of this observational study is to study intra-patient tumor and TME heterogeneity after initiation of hormonal therapy (ADT +- ARSI), while the patient is responding to treatment, to understand the drivers of hormonal therapy resistance and identify potential novel therapeutic targets in metastatic prostate cancer patients. The main question it aims to answer if intra-tumor adaptive mechanisms including expression of immune checkpoint proteins and changes in the tumor immune infiltrate are related to the induction of a senescent phenotype in response to hormonal therapy. Participants will asked to provide an FFPE and/or fresh biopsy sample from the primary tumor or a metastatic site at baseline (before starting hormonal therapy) and during the course of hormonal therapy. Additionally, a maximum of 2 blood tubes (10ml) will be collected each time.