The association of PD-L1 expression and CD8-positive T cell infiltration rate with the pathological complete response after neoadjuvant treatment in HER2-positive breast cancer

Sep 21, 2026

Pathological complete response (pCR) after neoadjuvant therapy in HER2-positive breast cancer is a key prognostic marker linked to lower recurrence risk and improved survival. This single-center retrospective study evaluates clinicopathological predictors of response, focusing on tumor-infiltrating lymphocytes (TILs), CD8-positive T lymphocytes, and PD-L1 expression. Data from 85 HER2-positive patients treated between 2017 and 2020 were analyzed using immunohistochemistry on selected paraffin blocks.

LanguageEnglish

CategoryHealthcare

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Pages11

Reading Time28 min

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Introduction

Breast Cancer Research and Treatment (2024) 205:17–27 [https://doi.org/10.1007/s10549-023-07242-1](https://doi.org/10.1007/s10549-023-07242-1) PRECLINICAL STUDY The association of PD-L1 expression and CD8-positive T cell infiltration rate with the pathological complete response after neoadjuvant treatment in HER2-positive breast cancer Kenan Çetin1 · Şermin Kökten2 · Bahar Sarıkamış3 · SedatYıldırım4 · Oruç Numan Gökçe1 · Nagehan Özdemir Barışık2 · Ülkan Kılıç3 Received: 7 September 2023 / Accepted: 26 December 2023 / Published online: 25 January 2024 © The Author(s) 2024 Abstract Purpose Achieving a pathological complete response (pCR) after neoadjuvant therapy in HER2-positive breast cancer patients is the most significant prognostic indicator, suggesting a low risk of recurrence and a survival advantage. This study aims to investigate clinicopathological parameters that can predict the response to neoadjuvant treatment in HER2 +breast cancers and to explore the roles of tumour-infiltrating lymphocytes (TILs), CD8 +T lymphocytes and PD-L1 expression. Methods This single-centre retrospective study was conducted with 85 HER2-positive breast cancer patients who underwent surgery after receiving neoadjuvant therapy between January 2017 and January 2020. Paraffin blocks from these patients were selected for immunohistochemical studies. Results A complete pathological response to neoadjuvant treatment was determined in 39 (45.9%) patients. High Ki-67 index (> 30%), moderate to high TIL infiltration, PD-L1 positivity and high CD8 cell count (≥25) were significantly associated with pCR in univariate analyses (p: 0.023, 0.025, 0.017 and 0.003, respectively) . Multivariate regression analysis identified high Ki-67 index (> 30%) and CD8 cell infiltration as independent predictors for pCR in HER2-positive breast cancer. Conclusions High Ki-67 index, and high CD8 cell count are strong predictors for pCR in HER2-positive breast cancer. Tumours with high Ki-67 index, high TILs and CD8 infiltration may represent a subgroup where standard therapies are adequate. Conversely, those with low TILs and CD8 infiltration may identify a subgroup where use of novel strategies, including those that increase CD8 infiltration could be applied. Keywords HER2 +breast cancer · Neoadjuvant therapy · Response · CD8 · PD-L1 􀀍 Kenan Çetin [drkenancetin@hotmail.com](drkenancetin@hotmail.com)[ ](drkenancetin@hotmail.com)Şermin Kökten[serminkokten@gmail.com](serminkokten@gmail.com)[ ](serminkokten@gmail.com)Bahar Sarıkamış [baharsarikamis@gmail.com](baharsarikamis@gmail.com)[ ](baharsarikamis@gmail.com)Sedat Yıldırım[azrass17@hotmail.com](azrass17@hotmail.com) Oruç Numan Gökçe[orucnumangokce@gmail.com](orucnumangokce@gmail.com)[ ](orucnumangokce@gmail.com)Nagehan Özdemir Barışık[nagehanob@yahoo.com](nagehanob@yahoo.com) Ülkan Kılıç [ulkan.kilic@sbu.edu.tr](ulkan.kilic@sbu.edu.tr) 1 Department of General Surgery, Faculty of Medicine,Çanakkale Onsekiz Mart University, Çanakkale, Turkey 2 Department of Pathology, University of Health Sciences, Kartal Dr. Lutfi Kırdar Training and Research Hospital, Istanbul, Turkey 3 Department of Medical Biology, Faculty of Medicine, University of Health Sciences, Istanbul, Turkey 4 Department of Medical Oncology, University of Health Sciences, Kartal Dr. Lutfi Kırdar Training and Research Hospital, Istanbul, Turkey Introduction Globally, breast cancer is the most diagnosed malignancy, with over two million cases reported each year [1] . It is also a leading cause of cancer-related deaths among women worldwide. It is a heterogeneous disease group consisting of different subtypes that exhibit varying tumour biology and behaviour. Approximately 20–30% of all breast cancers overexpress the human epidermal growth factor receptor 2 (HER2) [2] . Breast cancers that overexpress HER2 can achieve a pathological complete response (pCR) with anti-HER2 agents when given in combination with chemotherapy. Th

FAQs

What is the main purpose of the study?

To investigate clinicopathological parameters that predict pathological complete response after neoadjuvant treatment in HER2-positive breast cancer, with emphasis on TILs, CD8-positive T cells, and PD-L1 expression.

How was the study conducted?

It was a single-centre retrospective study of 85 HER2-positive breast cancer patients who underwent surgery after neoadjuvant therapy between January 2017 and January 2020, using immunohistochemical analysis of selected paraffin blocks.

Which factors were associated with pCR in the results?

High Ki-67 index (>30%), moderate to high TIL infiltration, PD-L1 positivity, and high CD8 cell count (≥25) were significantly associated with pCR in univariate analyses, and multivariate analysis identified Ki-67 and CD8 infiltration as independent predictors.

Sep 21, 2026

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