Spatial Profiling Reveals Immune Escape Pathways and Therapeutic Vulnerabilities in Prostate Cancer Bone Metastases

Area of Science:

• Immunology
• Oncology
• Cancer Biology

Background:

• Prostate cancer (PCa) commonly metastasizes to bone, leading to incurable disease.
• The bone tumor microenvironment is characterized by immune suppression, contributing to therapeutic resistance.
• Understanding these immunosuppressive mechanisms is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the mechanisms driving the immunosuppressive bone tumor microenvironment in prostate cancer.
• To identify key molecular and cellular features associated with immune evasion in bone metastases.
• To uncover potential therapeutic vulnerabilities in prostate cancer bone metastasis.

Main Methods:

• Spatial single-cell analyses were performed on primary tumors and bone metastatic sites.
• Digital spatial profiling was utilized to analyze matched tumor samples.
• Immunohistochemistry and gene expression analysis were employed to assess immune cell infiltration and molecular markers.

Main Results:

• Bone metastases exhibited suppressed tumor-intrinsic type I interferon (IFN-I) signaling and impaired antigen presentation.
• Reduced IFN-I signaling and antigen presentation correlated with poorer bone metastasis-free survival.
• The bone myeloid compartment showed enrichment of protumor macrophages and reduced dendritic cell (DC) activation.
• High expression of B7-H3, a potential IFN-I inhibitor, was observed in bone metastases and inversely correlated with antigen presentation.

Conclusions:

• Bone metastasis in prostate cancer is characterized by specific immune-suppressive mechanisms, including suppressed IFN-I signaling and antigen presentation.
• These findings highlight B7-H3 as a potential therapeutic target.
• The study identifies critical vulnerabilities in the bone tumor microenvironment that could inform precision therapeutic strategies for advanced prostate cancer.