Abstract B115: Epithelial stromal interaction 1 protein (ESPTI1) expression in breast cancers with known estrogen receptor, progesterone receptor and human epidermal growth receptors-2 immunoreactivity: Any prognostic indication?

Abstract Background: The heterogeneous nature of breast cancers has shifted the focus from pathogenesis, and clinicopathological correlations to prognostication; with increased attention being paid to identifying morphological features and biomarkers of prognostic significance. Objective: This study evaluated the expression pattern of EPSTI1protein biomarker in breast cancers with known Estrogen, Progesterone, and Human epidermal receptors (Her-2-neu) immunoreactivity. Methods: One hundred archived formalin fixed-paraffin embedded (FFPE) diagnosed breast cancer samples involving sixty-two triple-negative breast cancers (TNBC) and thirty-eight other breast cancer groups comprising mono negatives, bi negatives and triple positives were retrieved from the archives of the Department of Histopathology, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria. Real-time polymerase chain reaction (RT-PCR) of EPSTI1 was performed to determine EPSTI1 expression levels while immunohistochemistry was employed to determine ER, PR and Her-2 reactivity. Results: An increasing expression pattern of EPSTI1 in an ascending order ranging from triple-positive to triple-negative breast cancers was revealed. There was a significant increase in EPSTI1 levels in mono-negative cancers compared to mono-negative cancers. Similarly, a strong negative association between triple positive and triple negative cancers and mono positive and mono negative lesions were noted. Conclusion: The study revealed an inverse relationship between EPST1 and hormonal receptor expressions. EPST1 expression characterization of breast cancers may be explored further as a formidable prognostic and therapeutic biomarker for the more aggressive triple-negative breast cancers. Citation Format: Samuel Ifedioranma Ogenyi, Bruno Onochie Ezenwa, June Amara Onu, Amalachukwu Okwukwe Ike, Jude Ogechukwu Okoye, Samuel Ifedioranma Ogenyi. Epithelial stromal interaction 1 protein (ESPTI1) expression in breast cancers with known estrogen receptor, progesterone receptor and human epidermal growth receptors-2 immunoreactivity: Any prognostic indication? [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr B115.