Abstract
BACKGROUND: Breast cancer remains a predominant malignancy and a leading cause of oncologic mortality among women globally. The discovery of novel biomarkers is crucial for improving therapeutic outcomes. METHODS: We conducted a comprehensive analysis of the immunological and prognostic significance of hepatitis A virus cellular receptor 1 (HAVCR1) in breast cancer using publicly available datasets. RESULTS: HAVCR1 expression was markedly downregulated in breast cancer tissues. Significantly, lower expression levels of HAVCR1 in pre-treatment tumor samples were associated with poorer prognosis among pan-cancer patients undergoing immunotherapy, and a higher incidence of metastasis was observed in the breast cancer subgroup. Subtype-specific DEG analyses further indicated that distinct patterns of immune infiltration may underlie this association. Moreover, gene set enrichment analysis (GSEA) highlighted the immunological relevance of HAVCR1, particularly its involvement in T cell activation within the TNBC subtype. Clinically, elevated levels of HAVCR1 expression in pre-treatment T cells were indicative of a more favorable response to PD-1 blockade therapy compared to those with diminished expression. CONCLUSION: The expression of HAVCR1 exhibits a strong correlation with immune infiltration and holds potential as a prognostic biomarker for breast cancer, offering predictive insight into the efficacy of immunotherapeutic interventions.