Abstract PO5-16-02: Investigating survivin as a novel target for immunotherapy in diverse breast cancer patients
Authors: Hamilton Alina , Wang Qichen , Soppe Sarah , Troester Melissa , Abdou Yara 
Published: May 2024

Abstract
Background: The BIRC5 gene encodes survivin, a tumor-specific antigen associated with aggressive tumor features, Black race and poor prognosis in breast cancer (BC). Recent studies have shown that anti-survivin vaccines stimulate a strong anti-tumor immune response in multiple tumor types. However, the relationship between BIRC5/survivin and immune response in BC is poorly understood, particularly among diverse patients. In this analysis, we sought to investigate the relationship between BIRC5/survivin and the BC immune microenvironment across clinical tumor features and RNA-based risk scores for genomic instability. Methods: We leveraged the Carolina Breast Cancer Study (CBCS), a large population-based study that oversampled young (≤50 years) and Black women with invasive BC. NanoString mRNA expression profiling was used to evaluate breast tumor expression for 10 major immune cell types, adaptive and innate immune response, TP53 and homologous recombination deficiency (HRD) pathways, and BIRC5/survivin from 1952 BC patients, including 1,030 (53%) Black and 922 (47%) non-Black women from the CBCS, with additional comparison in The Cancer genome Atlas (TCGA) (n=1,095 breast tumors). BIRC5 was evaluated both as a continuous and categorical variable, using the third expression quartile as a cut point for BIRC5-high, with the lower three quartiles categorized as BIRC5-low. We used generalized linear models to estimate beta values and adjusted p-values as the measure of association between BIRC5 status and immune-related expression in strata defined by estrogen receptor (ER) status, tumor stage, TP53 and HRD status. All analyses were adjusted for multiple comparisons with the Benjamini-Hochberg procedure. Results: In an analysis of continuous BIRC5 expression and global classes of immune response, BIRC5 mRNA expression was highest among tumors with an adaptive-enriched immune class (p&lt; 0.001) in both CBCS and TCGA. However, when investigating immune gene expression according to BIRC5 status (i.e., BIRC5-high relative to BIRC5-low), multivariate differential expression analysis revealed significantly decreased immune cell-related expression scores among BIRC5-high tumors relative to BIRC5-low, and this relationship persisted in analysis stratified on stage (I/II vs III/IV), ER status, TP53 and HRD status. Across all strata, the strongest relationship between BIRC5-high and the immune microenvironment was observed for adaptive immune response (Beta: -0.14; p=0.005), with decreased immune gene expression related to B cells (Beta: -0.16; p=0.01), T cells (Beta: -0.14; p=0.007), Cytotoxic cells (Beta: -0.14; p=0.005), and PD-L1 (Beta: -0.15; p=0.005), relative to BIRC5-low. Conclusion: High BIRC5/survivin expression is associated with decreased immune-related gene expression in both ER-positive and ER-negative disease, and across all tumor stages. Anti-survivin therapies may be beneficial for boosting immune response in breast tumors with low immunogenicity, offering promise for BC subtypes previously ineligible for immunotherapy.
Citation Format: Alina Hamilton, Qichen Wang, Sarah Soppe, Melissa Troester, Yara Abdou. Investigating survivin as a novel target for immunotherapy in diverse breast cancer patients [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-16-02.