Abstract 4566: PD-L1 and B7-H3 expression in serous carcinoma of endometrium

Abstract

Abstract Endometrial cancer keeps increasing in Japan explosively. In endometrial cancer, the prognosis of serous carcinoma is very poor, because of early progression to abdominal cavity. Remedy for endometrial cancer is limited, so new therapy has been required for a long time. Immunotherapy is very promising in various cancers recently. PD-L1 (programmed cell death ligand 1) and B7-H3 are factors of immunoresponse between cancer cells and lymphcyte. Purpose: The purpose of this study is to investing the expression of PD-L1 and B7-H3, moreover, relationship with clinicopathological factors in serous carcinoma of endometrium. We immunohistochemically evaluated PD-L1 and B7-H3 expression in 21 serous carcinoma. The result was graded as positive in case stained more than 10% area. Result: 2/21(9.5%) for PD-L1 and 10/21(47.6%) for B7-H3 were positive. There was no correlation with tumor diameter, lymphnode metastasis, advanced stage and recurrence in PD-L1, however, B7-H3 expression had trend node metastasis, 3/10 in positive cases vs 0/11 in negative cases (p=0.05). In 4 recurrent cases treated with taxane and carboplatin as second line therapy, one case with B7-H3 negative got complete remission, however 3 cases with B7-H3 positive got partial improvement once, but finally got progression. Conclusion: PD-L1 expression was limited in serous carcinoma, so immunotherapy targeted for PD-1 and PD-L1 may be limited. The expression of B7-H3 is related to chemotherapy resistance. B7-H3 may be a biomarker for chemotherapy and target of new immunotherapy for serous carcinoma of endometrium. Citation Format: Masato Nishimura, Ayuka Mineda, Akiko Abe, Minoru Irahara. PD-L1 and B7-H3 expression in serous carcinoma of endometrium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4566.