This study is a companion to the SYNERGY-201 clinical trial (NCT06228053), which investigates SX-682 and enzalutamide in individuals with prostate cancer. Individuals must be participating in SYNERGY-201 in order to participate in this study. The purpose of this companion study is to learn more about biomarkers, particularly a biomarker called CXCR2, and investigate if CXCR2 can predict who will receive benefit from the SYNERGY-201 drug combination. This study will also investigate how CXCR2 and other biomarkers change over time when participants receive the SYNERGY-201 drug combination. CXCR2 is of particular interest because the SYNERGY-201 drug, SX-682, inhibits CXCR2. After participants provide consent, blood samples will be collected for research purposes at three SYNERGY-201 visits (Baseline, Cycle 3 Day 1 and End of Study Drug). Up to 20 participants will also receive tumor biopsies at the Baseline and SYNERGY-201 Cycle 3 Day 1 visits. Clinical and study data collected as part of SYNERGY-201 will also be used for this study.