Abstract 947: Differential expressions of immune check point receptors on tumor infiltrating lymphocytes after neo-adjuvant chemotherapy (NAC) in patients with locally advanced breast cancer (LABC)

Background: Recent advances in tumor biology and immune system have identified check points modulating the anti-tumoral immune response. This study aimed to determine immune check point expressions patients with locally advanced breast cancer to explore any associations between clinical and prognostic factors to show effectiveness of targeted therapies for these molecules. Materials and Methods: This prospective study was carried out between September 2018 and November 2019 in the Department of General Surgery of Istanbul University Istanbul Faculty of Medicine Breast Unit. Twenty-four patients with LABC with a partial response to neoadjuvant chemotherapy (NAC) were included in the study. Tumor infiltrating lymphocytes (TILs) were isolated from the residual tumor burden separated from the surgical material with cell dissociation kit by using MACS tumor separation device. Expressions of immune checkpoints receptors including PD-1, LAG-3, TIM-3, TIGIT and CTLA-4 on CD8 T lymphocytes and Natural Killer (NK) cell subsets obtained from TIL were analyzed by using flow cytometry. Results: TILs of patients Conclusion: Our results suggest that patients with a younger age and advanced tumor burden are more likely to benefit from immunotherapeutical approaches using immune check point inhibitors. Furthermore, combination of systemic chemotherapy with immunotherapy may increase the pathologic response rate in breast cancer patients. Citation Format: Ayxan Abbasov, Esin Cetin, Neslihan Cabioglu, Baran Mollavelioglu, Semen Onder, Selman Emiroglu, Mustafa Tukenmez, Mahmut Muslumanoglu, Abdullah Igci, Gunnur Deniz, Vahit Ozmen. Differential expressions of immune check point receptors on tumor infiltrating lymphocytes after neo-adjuvant chemotherapy (NAC) in patients with locally advanced breast cancer (LABC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 947.