Abstract P1-22-03: Expression of immune-related genes and breast cancer recurrence in women with ductal carcinoma in situ
Authors: Rocco Elena Guerini , Fumagalli Caterina , Concardi Alberto , Taormina Sergio V. , Guerrieri-Gonzaga Aliana , Corso Federica , Gandini Sara , Bonanni Bernardo , Viale Giuseppe , Barberis Massimo , Fusco Nicola , Matteo Lazzeroni 
Published: March 2022

Abstract
Background. Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive breast cancer (IBC). High variability in clinical outcomes and propensity for invasion among DCIS is reported, but identifying high-risk DCIS remains a major clinical challenge. Therefore, biomarkers to differentiate patients with indolent DCIS from those who would benefit from therapy are warranted. There are recent data on the role of the tumor immune microenvironment in the progression from DCIS to IBC and the risk of recurrences. However, no comprehensive information on the clinical actionability of DCIS immune-biology is available. We hypothesize that immune escape mechanisms might play a critical role in the transition from DCIS to IBC. Here, we sought to establish whether immune-related gene expression signatures of DCIS might identify women at high risk of disease recurrence and/or progression. Methods. We performed a retrospective nested case-control study including women with pure DCIS, diagnosed between 2009 and 2015 at European Institute Oncology (median follow-up 39,5 months) treated with conserving surgery +/- adjuvant therapy (endocrine therapy or radiotherapy). The study group (cases) was composed of women with DCIS and subsequent ipsilateral breast events (IBE, in situ or invasive). Controls were selected in a 1.1 ratio among DCIS without IBE, matched for age, tumor size, treatment, and hormone receptors (HR), and HER2 status. Stromal tumor-infiltrating lymphocytes (sTILs) were assessed according to the International Immuno-Oncology Biomarker Working Group on Breast Cancer guidelines. RNA extracted from formalin-fixed paraffin-embedded blocks was subjected to gene expression analysis using a next-generation sequencing assay (Oncomine™ Immune Response Research Assay) targeting 395 immune-related genes. Samples that achieve run quality parameters (mapped reads &gt;1 million, valid reads &gt;800.000) were further processed with the Affymetrix Transcriptome Analysis Console software to compare the gene expression between cases and controls (ANOVA, gene-level fold change &lt;-2 or &gt;2).Results. A total of 116 patients were included, 58 cases and 58 controls. High sTILs count was significantly associated with high-grade DCIS (p=&lt;0,0001), the presence of necrosis (p=0,0210) and HER2 expression (p=&lt;0,0001) in both groups. No significant association between sTILs count and the probability of relapse was observed. Gene expression data were available for 56 cases and 56 controls that achieved sequencing quality parameters. Overall, five genes were differentially expressed between cases and controls. In particular, cases showed upregulation of IFNA17 (p-value &lt;0,0001; FDR p-value &lt;0.0001), IFNB1 (p-value &lt;0,0001; FDR p-value &lt;0.0001), PECAM-1 (p-value &lt;0,0001; FDR p-value &lt;0.0001) and significant lower expression of CCL2 (p-value &lt;0,0001; FDR p-value &lt;0.0001) as compared to control group. Other genes that were upregulated in DCIS with IBE included FCGR2B, CD3D, CD40LG, while TCF7, CDKN3, ADORA2A were found to be downregulated (p-value &lt;0.05).Conclusion. Quantitative TILs density assessment remains of modest significance in DCIS prognostication in terms of risk of IBE. We showed that pure DCIS displayed significant differences in the expression of immune-related genes between women with and without subsequent breast cancer recurrence regardless of HR and HER2 status. The activation of immune-related pathways might play a part in the development of IBE in patients with a diagnosis of DCIS. The evaluation of immune-related gene expression profiles might improve risk stratification in patients with DCIS.
Citation Format: Elena Guerini Rocco, Caterina Fumagalli, Alberto Concardi, Sergio V. Taormina, Aliana Guerrieri-Gonzaga, Federica Corso, Sara Gandini, Bernardo Bonanni, Giuseppe Viale, Massimo Barberis, Nicola Fusco, Lazzeroni Matteo. Expression of immune-related genes and breast cancer recurrence in women with ductal carcinoma in situ [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-22-03.