Abstract P5-23-05: Prognostic value of PD-L1 expression in male breast cancer

• Published in: Cancer research (Chicago, Ill.) Vol. 78; no. 4_Supplement; pp. P5 - P5-23-05
• Main Authors: Abdeljaoued, S, Bettaieb, I, Adouni, O, Goucha, A, Chiba, D, Bouzaiene, H, Ben Hassouna, J, Boussen, H, Rahal, K, Gamoudi, A
• Format: Journal Article
• Language: English
• Published: 15.02.2018
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS17-P5-23-05

Abstract Background Growing evidence have shown promise for targeting programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) signaling in several tumors. In female breast cancer, PD-L1 expression has been correlated with poor clinical outcome. However, whether PD-L1 has any indication for prognosis in male breast cancer (MBC) patients remains unknown. The purpose of this study was to examine the expression levels of PD-L1 in MBC and to identify the relationship between PD-L1 expression and patient survival. Methods We retrospectively identified 110 male breast cancer patients diagnosed between 2000 and 2013 at Salah Azaïz Cancer Institute. PD-L1 expression was evaluated by immunohistochemistry (IHC) using CD274 antibody. Specimens were scored as IHC low or high, when < 5% or ≥ 5% of cells were PD-L1 positive, respectively. The association between expression of PD-L1 and survival was investigated using Kaplan-Meier survival and COX proportional hazard regression analyses. Results Median follow up was 12.5 months [range 1-132 months]. High expression of PD-L1 was observed in 64.5% of MBC samples (71/110). PD-L1 expression was significantly associated with advanced clinical stage (p=0.012), higher histological grade (p=0.014), higher Ki67 expression (p=0.023) and hormone-receptor negative status (p=0.024). Patients with high PD-L1 expression had significantly shorter overall survival (OS) than patients with low expression (p=0.002, hazard ratio (HR) =5 [2.624–10.642]). Multivariate analysis identified PD-L1 as an independent prognostic factor for OS (p<0.001, HR = 0.775 [0.680–0.870]). Conclusion Our results indicate that high PD-L1 expression may be a prognostic indicator for reduced OS. Thus, PD-L1 expression is a promising novel biomarker with prognostic significance in MBC and may suggest a potential therapeutic target of anti-PD-L1 antibody therapy in MBC patients. Citation Format: Abdeljaoued S, Bettaieb I, Adouni O, Goucha A, Chiba D, Bouzaiene H, Ben Hassouna J, Boussen H, Rahal K, Gamoudi A. Prognostic value of PD-L1 expression in male breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-23-05.