# Assessment of Immune Cell Populations in the Peripheral Blood of Patients With Metastatic Prostate Cancer

## TL;DR

This study compares immune cell populations in the blood of prostate cancer patients with different levels of metastasis to identify potential biomarkers and treatment targets.

## Contribution

The study identifies γδ2+ T cells as a potential immune biomarker in metastatic prostate cancer.

## Key findings

- OMPC patients had significantly more γδ2+ T cells than PMPC patients.
- PMPC patients showed a trend toward higher IFN-γ expression in γδ2+ T cells.
- No significant differences were found in other immune cell subsets between the groups.

## Abstract

Background

Prostate cancer (PCa) encompasses a heterogeneous spectrum, ranging from indolent to highly aggressive forms, with approximately 10-20% of patients with initially localized disease later becoming metastatic. Oligometastatic PCa (OMPC) represents an intermediate state between locally advanced and high-volume metastatic disease. Understanding the immune landscape of OMPC and plurimetastatic PCa (PMPC) can provide valuable insights into disease biology, with potential implications for treatment strategies and prognosis.

Aim and objective

This study aimed to evaluate alterations in circulating immune cell subsets between OMPC and PMPC to identify potential immune biomarkers and therapeutic targets.

Methods

We conducted a retrospective cohort study of 43 mPC patients. Patients were stratified into two groups based on metastatic spread: OMPC (≤5 metastatic lesions in bone or lymph nodes) and PMPC (>5 lesions and/or visceral involvement). Peripheral blood mononuclear cells (PBMCs) were isolated and analyzed via flow cytometry for key immune subsets, including γδ T cells, αβ T cells, and regulatory T cells, with functional assessments performed using cytokine stimulation. Statistical analysis used the Mann-Whitney-Wilcoxon test, with p ≤ 0.05 considered significant.

Results

OMPC patients exhibited significantly increased γδ2+ T cells compared to PMPC, suggesting enhanced immune surveillance in low metastatic burden. A trend toward elevated γδ2+ T cells expressing interferon-gamma (IFN-γ) was observed in PMPC. No significant differences were observed in other immune subsets.

Conclusions

γδ2+ T cells represent a distinct immune subset in PCa, potentially influencing disease progression. Despite the small sample size, these findings highlight γδ2+ T cells as promising biomarkers and therapeutic targets. Prospective studies with a larger sample size are warranted to confirm the significance of these findings and explore the mechanistic roles of these cells and possible clinical applications in metastatic PCa (mPC).