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

• Published in: Breast cancer research and treatment Vol. 205; no. 1; pp. 17 - 27
• Main Authors: Çetin, Kenan, Kökten, Şermin, Sarıkamış, Bahar, Yıldırım, Sedat, Gökçe, Oruç Numan, Barışık, Nagehan Özdemir, Kılıç, Ülkan
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2024; Springer Nature B.V
• Subjects: Adult; Aged; B7-H1 Antigen - metabolism; Biomarkers, Tumor - metabolism; Breast cancer; Breast Neoplasms - drug therapy; Breast Neoplasms - immunology; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Breast Neoplasms - therapy; Cancer therapies; CD8 antigen; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - metabolism; ErbB-2 protein; Female; Humans; Infiltration; Lymphocytes T; Lymphocytes, Tumor-Infiltrating - immunology; Lymphocytes, Tumor-Infiltrating - metabolism; Medicine; Medicine & Public Health; Metastases; Middle Aged; Neoadjuvant Therapy - methods; Oncology; Patients; PD-L1 protein; Preclinical Study; Prognosis; Receptor, ErbB-2 - metabolism; Retrospective Studies; Treatment Outcome; Response; PD-L1; Neoadjuvant therapy; HER2 + breast cancer; CD8
• ISSN: 0167-6806; 1573-7217
• DOI: 10.1007/s10549-023-07242-1

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.