Metaplastic breast cancers frequently express immune checkpoint markers FOXP3 and PD-L1

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Metaplastic breast carcinoma is a rare, aggressive cancer subtype with diverse mesenchymal differentiation.
• It is often chemo-resistant and lacks hormone receptor expression, limiting conventional treatment options.
• Emerging immunotherapies targeting PD-L1 and Tregs offer potential therapeutic avenues.

Purpose of the Study:

• To investigate the expression of PD-L1 and FOXP3 in metaplastic breast cancer.
• To assess the prognostic significance of tumor-infiltrating lymphocytes (TILs) and FOXP3 expression.
• To evaluate the potential for immune-based therapies in metaplastic breast cancer.

Main Methods:

• Immunohistochemical analysis of PD-L1 and FOXP3 expression.
• Quantification of tumor-infiltrating lymphocytes (TILs).
• Survival data analysis in a cohort of metaplastic breast cancer patients.

Main Results:

• Metaplastic breast cancers showed significantly higher PD-L1 tumor cell expression compared to triple-negative ductal breast cancers.
• No significant difference in PD-L1 positive TILs was observed.
• FOXP3+ TILs were significantly enriched and associated with an adverse prognostic outcome.
• Multivariate analysis confirmed FOXP3+ TILs as an independent prognostic factor.

Conclusions:

• PD-L1, FOXP3, and TILs hold clinical significance in metaplastic breast cancer.
• FOXP3+ TILs are a valuable independent prognostic marker.
• A subset of metaplastic breast cancer patients may benefit from immune-based therapies targeting PD-1/PD-L1 checkpoints.