Abstract P1-22-03: Expression of immune-related genes and breast cancer recurrence in women with ductal carcinoma in situ

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 >1 million, valid reads >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 <-2 or >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=<0,0001), the presence of necrosis (p=0,0210) and HER2 expression (p=<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 <0,0001; FDR p-value <0.0001), IFNB1 (p-value <0,0001; FDR p-value <0.0001), PECAM-1 (p-value <0,0001; FDR p-value <0.0001) and significant lower expression of CCL2 (p-value <0,0001; FDR p-value <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 <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.

Molecular characterization of extrahepatic cholangiocarcinoma: perihilar and distal tumors display divergent genomic and transcriptomic profiles

BACKGROUND

Extrahepatic cholangiocarcinoma (ECC) is classified into two subtypes based on anatomic origin: distal extrahepatic (DECC) and perihilar (PHCC) cholangiocarcinoma. This study aimed to shed light on its genomic and transcriptomic profiles.

RESEARCH DESIGN AND METHODS

The genomic alterations of 99 ECC (47 PHCC and 52 DECC) were investigated by next-generation sequencing of 96 genes. A subgroup of cases, representative of each subtype, was further investigated using transcriptomic analysis. Bioinformatics tools were applied for clustering and pathway analysis and defining the immune composition of the tumor microenvironment.

RESULTS

PHCC had more frequent KRAS mutations (p = 0.0047), whereas TP53 mutations were more common in DECC (p = 0.006). Potentially actionable alterations included high-tumor mutational burden and/or microsatellite instability (7.1%), PI3KCA mutations (8.1%), and MYC (10.1%) and ERBB2 amplification (5.1%). The transcriptomic profiles showed the presence of three distinct clusters, which followed the anatomic origin and differed in immune microenvironment. DECC appeared to contain two distinct tumor subgroups, one enriched for druggable alterations and one lacking actionable opportunities.

CONCLUSIONS

This study provides new insights into the molecular landscape and the actionable alterations of ECC. Our findings represent a step toward improved ECC molecular taxonomy and therapeutic strategies for precision oncology.

Tumor Mutational Burden as a Potential Biomarker for Immunotherapy in Pancreatic Cancer: Systematic Review and Still-Open Questions

Simple Summary

Tumor mutational burden (TMB) represents the number of mutations per megabase (muts/Mb) harbored by tumor cells in a given neoplasm, and can be determined with next-generation sequencing. High values are an indicator of potential response to immunotherapy. With this systematic review, we assessed its role in pancreatic ductal adenocarcinoma (PDAC). Our main findings can be summarized as: (i) high-TMB can be found in about 1% of PDAC; (ii) it is associated with mucinous/colloid and medullary histology; (iii) high-TMB PDAC frequently harbor other actionable alterations, with microsatellite instability as the most common; (iv) immunotherapy has shown promising results in high-TMB PDAC.

Abstract

Tumor mutational burden (TMB) is a numeric index that expresses the number of mutations per megabase (muts/Mb) harbored by tumor cells in a neoplasm. TMB can be determined using different approaches based on next-generation sequencing. In the case of high values, it indicates a potential response to immunotherapy. In this systematic review, we assessed the potential predictive role of high-TMB in pancreatic ductal adenocarcinoma (PDAC), as well as the histo-molecular features of high-TMB PDAC. High-TMB appeared as a rare but not-negligible molecular feature in PDAC, being present in about 1.1% of cases. This genetic condition was closely associated with mucinous/colloid and medullary histology (p < 0.01). PDAC with high-TMB frequently harbored other actionable alterations, with microsatellite instability/defective mismatch repair as the most common. Immunotherapy has shown promising results in high-TMB PDAC, but the sample size of high-TMB PDAC treated so far is quite small. This study highlights interesting peculiarities of PDAC harboring high-TMB and may represent a reliable starting point for the assessment of TMB in the clinical management of patients affected by pancreatic cancer.