Immune Checkpoint and EMT-Related Molecules in Circulating Tumor Cells (CTCs) from Triple Negative Breast Cancer Patients and Their Clinical Impact

Vasileios Vardas; Anastasios Tolios; Athina Christopoulou; Vassilis Georgoulias; Anastasia Xagara; Filippos Koinis; Athanasios Kotsakis; Galatea Kallergi

doi:10.3390/cancers15071974

Immune Checkpoint and EMT-Related Molecules in Circulating Tumor Cells (CTCs) from Triple Negative Breast Cancer Patients and Their Clinical Impact

Cancers (Basel). 2023 Mar 25;15(7):1974. doi: 10.3390/cancers15071974.

Authors

Vasileios Vardas¹, Anastasios Tolios¹, Athina Christopoulou², Vassilis Georgoulias³, Anastasia Xagara⁴, Filippos Koinis^{4

5}, Athanasios Kotsakis^{4

5}, Galatea Kallergi¹

Affiliations

¹ Laboratory of Biochemistry/Metastatic Signaling, Section of Genetics, Cell Biology and Development, Department of Biology, University of Patras, GR-26504 Patras, Greece.
² Oncology Unit, ST Andrews General Hospital of Patras, GR-26332 Patras, Greece.
³ Hellenic Oncology Research Group (HORG), GR-11526 Athens, Greece.
⁴ Laboratory of Oncology, Faculty of Medicine, School of Health Sciences, University of Thessaly, GR-41110 Larissa, Greece.
⁵ Department of Medical Oncology, University General Hospital of Larissa, GR-41110 Larissa, Greece.

Abstract

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype. There are few targeted therapies for these patients, leading to an unmet need for new biomarkers. The present study aimed to investigate the expression of PD-L1, CTLA-4, GLU, and VIM in CTCs of TNBC patients. Ninety-five patients were enrolled in this study: sixty-four TNBC and thirty-one luminal. Of these patients, 60 were in the early stage, while 35 had metastatic disease. Protein expression was identified by immunofluorescence staining experiments and VyCAP analysis. All the examined proteins were upregulated in TNBC patients. The expression of the GLU⁺VIM⁺CK⁺ phenotype was higher (50%) in metastatic TNBC compared to early TNBC patients (17%) (p = 0.005). Among all the BC patients, a significant correlation was found between PD-L1⁺CD45^-CK⁺ and CTLA-4⁺CD45^-CK⁺ phenotypes (Spearman test, p = 0.024), implying an important role of dual inhibition in BC. Finally, the phenotypes GLU⁺VIM⁺CK⁺ and PD-L1⁺CD45^-CK⁺ were associated with shorter OS in TNBC patients (OS: log-rank p = 0.048, HR = 2.9, OS: log-rank p < 0.001, HR = 8.7, respectively). Thus, PD-L1, CTLA-4, GLU, and VIM constitute significant biomarkers in TNBC associated with patients' outcome, providing new therapeutic targets for this difficult breast cancer subtype.

Keywords: CTLA-4; PD-L1; breast cancer; circulating tumor cells; detyrosinated α-tubulin (GLU); luminal; triple negative breast cancer; vimentin (VIM).

Grants and funding

This research has been co-financed by the European Regional Development Fund of the European Union and Greek funds through the Operational Program Competitiveness Entrepreneurship and Innovation, under the call RESEARCH–CREATE–INNOVATE (project code: T1EDK-01562). This research was also funded by a grant from the Research Committee of the University of Patras via the “C. CARATHEODORI” program (project code: 81351).