ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 V. Kometova*, I. Kolyadina, L. Mikhaleva, M. Rodionova, M. Dardyk, V. Rodionov *FSBI "V.I.Kulakov NMRC for OGP", Russia Ba ckg round & ob j e c t i ve s : So l u t e c a r r i e r fami ly7 member5(SLC7A5), known as LAT1, is a transporter factor deliv- ering amino acids to cancer cells.SLC7A5 is an important prog- nostic marker of the breast cancer(BC) aggressive behaviour. This study aimed to investigate correlation between SLC7A5 expression and molecular subtypes. Methods: We tested the expression of SLC7A5 in 358 BC speci- mens by immunohistochemistry (PA5-34215, ThermoFisher, USA). Full membranous staining in >10% tumour cells was considered as positive. Moderate/strong SLC7A5-positive expression was detected in 199 cases (55.6%). Loss of SLC7A5 expression was detected only in 56 cases(15.6%). Strong membranous staining in >50% tumour cells was determined in a quarter of cases(26.5%). Results: SLC7A5 expression was increased in BC with HER2/ neu overexpression, regardless of hormonal receptor status. Strong SLC7A5 expression was detected in 14 cases(66.7%) of luminal B HER2-positive subtype and in 12 cases (80%) of non-luminal HER2-positive subtype. There was no SLC7A5-negative BC cases with HER2/neu overexpression. In TN breast cancer and in luminal B subtypes, the transport protein was expressed more than in half cases, with approximately the same frequency in all three subtypes – 65%-66.7%. In luminal A subtype, cases with no SLC7A5 expres- sion were 1.5 times more often (34 cases, 21%) than in luminal B HER2-negative BC (18 cases, 14.5%)(p<0.001). Conclusion: We demonstrated that SLC7A5-expression is associ- ated with molecular BC subtypes (p<0.001). SLC7A5-negative BC positively correlates with luminal-A subtype. The largest number of cases with strong SLC7A5 expression in >50% cancer cells was detected in cases of non-luminal BC subtype with HER2/neu overexpression. These results suggest that SLC7A5 plays a role in the biology of BC. Funding: НИОКТР АААА-А18-118053190016-7 PS-01-013 Comparison of HercepTest™ mAb pharmDx (Dako Omnis) (GE001) with Ventana PATHWAY anti-HER-2/neu (4B5) in breast cancer J. Rüschoff*, M. Friedrich, I. Nagelmeier, M. Kirchner, L. Andresen, K. Salomon, B. Portier, S. Sredni, H.U. Schildhaus, B. Jasani, M. Grzelinski, G. Viale *Targos - A DLS company, Germany Background & objectives: For HER2 assessment in Breast Cancer, immunohistochemistry (IHC) staining is the method of choice. Here, we compare the clinical performance of the new CE-IVD-marked HercepTest™ mAb pharmDx (Dako Omnis) (GE001) with Ventana PATHWAY anti-HER-2/neu (4B5). Methods: In total, 119 pre-selected breast cancer samples cover- ing the entire range of HER2 IHC expression scores were tested by HercepTest (mAb), PATHWAY 4B5, and fluorescent in situ hybridization (FISH). Three pathologists independently evaluated HER2 IHC according to 2018 American Society of Clinical Oncol- ogy/College of American Pathologists guidelines. Sensitivity and specificity of both IHC assays were assessed based on FISH data. Results: There was a high concordance between results from the Her- cepTest (mAb) and PATHWAY 4B5 assays for HER2-negative (IHC 0, 1+, 2+ and FISH negative) and HER2-positive (IHC 3+, 2+ and FISH positive) breast carcinomas (98.2%). Regarding individual IHC scores, complete agreement was achieved in 69.7% (83/119) of cases and all but one of the discordant cases were due to higher HER2-status scoring using the HercepTest (mAb). Thus, more tumours were scored as IHC 2+ by HercepTest (mAb) (27 versus 15) as evidenced by their lower FISH positivity rate (48.1% versus 80%). However, two amplified tumours identified as IHC 2+ by HercepTest (mAb) were missed by PATHWAY 4B5 (IHC 1+). Conclusion: The HercepTest (mAb) detects HER2 expression with higher sensitivity in tumours with gene amplification (ISH group 1) and increased gene counts (ISH group 4) as well as in HER2- low tumours (HER2 IHC 2+ / FISH negative or IHC 1+). These findings could be critical for the identification of patients eligible to new HER2-targeting treatment options. Future studies will dem- onstrate whether this new assay has the capacity to provide better patient stratification, leading to better patient response rates and clinical outcomes. Funding: This study was funded by Agilent Technologies, Inc. PS-01-014 Phosphohistone H3 versus mitotic count in breast cancer grad- ing: a single institution study N. Mansouri*, F. Gargouri, M. Ben Thayer, K. Tlili, R. Aouadi, I. Msakni, B. Laabidi *Department of Pathology, Military Hospital of Tunis, Tunisia Background & objectives: Mitotic index is an important prognosis marker in invasive breast carcinoma (BC). The aim of this study was to evaluate the utility of Phosphohistone H3 in grading of BC in comparison with mitotic count on hematoxylin and eosin- stained slides. Methods: A retrospective study on a series of 40 BCs diagnosed from March 2020 to August 2021 at the Pathology Department of the Mili- tary Hospital of Tunis was performed. We compared grade variability according to the mitotic count on H&E-stained slides and on PHH3 stained slides. Results: Although, mean average count was higher by IHC method, good correlation was observed (R²=0.799). Using PHH3 IHC, three cases of grade I tumours were upgraded in to grade II and six cases of grade II were upgraded in to grade III. None of the tumours were downgraded. Conclusion: In summary, we have performed the first study to explore the utility of PHH3 in breast cancer grading in Tunisia. Similar to some other previous studies, we found PHH3 a robust sensitive and practical marker for mitotic count in breast carcinoma. Especially it is helpful to identify the most proliferating area. PS-01-015 Immune checkpoint genes expression in breast carcinoma: cor- relation with clinicopathological features and patients’ survival Y.G. Montoyo Pujol*, M. García-Escolano, T. Martin-Bayon, S. Delgado-García, H. Ballester, J.J. Ponce, E. Castellón-Molla, J.M. Sempere-Ortells, F.I. Aranda López, G. Peiró *University General Hospital and Alicante Institute for Health and Biomedical Research –ISABIAL-, Spain Background & objectives: Immune checkpoints deregulation can lead to tumour progression and invasion. However, very little data is available on breast carcinoma (BC). Therefore, we analysed CTLA-4, PDCD1, CD274, PDCD1LG2, and CD276 expression in BC and their association with clinicopathological factors and survival. Methods: We included 275 non-consecutive BC. mRNA expression was analysed by qRT-PCR using TaqMan® primers and probes. PUM1 and β-actin were used as reference genes, and healthy breast tissue served as a calibrator. The 2-ΔΔCT calculated relative changes in expression. Results were correlated with clinicopathological factors and prognosis. Significant differences were calculated with χ 2 and log-rank test. S64