Abstract PD4-08: Relationship between FDG-uptake and expression level of PD-L1 in primary ER positive/HER2 negative breast cancer

Abstract

Abstract Background: 18F-Fluorodeoxyglucose-positron emission tomography (FDG-PET) is used to evaluate the glucose metabolic rates of cancers. Several studies have reported that high FDG uptake is predictive of poor prognosis and aggressive features in patients with breast cancer (BC). FDG-uptake is influenced by many factors including inflammation. In this study, we investigated the relationship between FDG uptake and immunological factors, including degrees of stromal tumor-infiltrating lymphocytes (TILs), CD8 and programmed cell death ligand 1 (PD-L1) in ER positive/HER2 negative (ER+/HER2-) BC. No published study, to our knowledge, has assessed the association between FDG uptake and PD-L1 in BC cases, even though both represent prognosis. Methods: Invasive carcinoma tissues of 79 ER+/HER2- BC patients who underwent surgery without preoperative therapy were examined. PD-L1, CD8 and TILs expression were evaluated by immunohistochemically (IHC) method. The evaluation of PET was determined by standardized uptake value max (SUVmax). Multivariate linear regression analysis, including expression of PD-L1, CD8 and TILs, was performed to identify independent variable correlation with SUVmax. Results: Among the 79 ER+/HER2- BC (T1-4, N0-2, M0) patients, the analysis revealed that PD-L1 (P=0.005), lymphovascular invasion (P=0.011), large tumor size (p=0.001), lymph node meatstasis (P=0.010), and high nuclear grade (P=0.011) and premenopasal status (P=0.014) were significantly associated with high SUVmax in the primary tumor. To define predictive value for the expression of PD-L1, SUVmax cut offwas determined using receiver operating characteristic (ROC) analysis; low (<3.0) and high (≥3.0). Among the 30 cases with high SUVmax, 10 cases (33.3%) had PD-L1 positive expression in the primary tumor, while only 2 (4.1%) of the 49 cases with low SUVmax had PD-L1 positive expression in the primary tumor. Conclusions: The present study demonstrated that the finding of preoperative FDG uptake is associated with the expression of PD-L1 in ER+/HER2- BC. In light of our results, FDG uptake may be predictive of the expression of PD-L1 and may be reflective of immunological features as well as prognostic features among patients with ER+/HER2- BC. Citation Format: Hirakata T, Fijii T, Kaira K, Kurozumi S, Katayama A, Yajima R, Obayashi S, NaKazawa Y, Tokuda S, Yanai K, Shirabe K. Relationship between FDG-uptake and expression level of PD-L1 in primary ER positive/HER2 negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD4-08.