2024 Asia Conference on Lung Cancer (ACLC) - Poster & ePosters-PP01.19

PP01.19 - Kei Chubachi

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This study aimed to evaluate PD-L1 expression in thymic epithelial tumors (TETs), specifically thymoma and thymic carcinoma, using two different antibodies, SP142 and SP263, to understand variations in expression patterns. PD-L1 is a protein linked to tumor immune evasion and is of interest due to its relationship with immune checkpoint inhibitors' efficacy.<br /><br />A retrospective analysis was conducted on tumor specimens from 50 patients diagnosed with thymoma or thymic carcinoma at Hirosaki University Hospital from 2000 to 2020. The study used the 2015 WHO classification for histological categorization and focused on PD-L1 expression in tumor cells (TCs) and tumor-infiltrating lymphocytes (TILs).<br /><br />Results indicated high PD-L1 expression on TCs and TILs in many TETs cases, reaffirming prior findings. A significant difference in PD-L1 expression between SP142 and SP263 was observed across different histological types. For example, in thymoma cases, SP263 showed 46% high expression compared to SP142's 27% for the same tumor category. Similarly, in thymic carcinoma, SP263 indicated a 64% high expression, in contrast to 36% with SP142.<br /><br />The study suggests that the variability in PD-L1 expression related to different antibodies should be a consideration when using immune checkpoint inhibitors in treating TETs. Although high PD-L1 expression is associated with certain prognosis markers, the variability based on antibody use highlights the need for careful selection in clinical applications to improve treatment outcomes.<br /><br />The reference list includes pivotal sources on thymic epithelial tumors and immune checkpoint inhibitor therapy, grounding this research in established clinical and pathological contexts. Overall, the study underscores the potential for leveraging PD-L1 expression information in therapeutic decision-making for TETs.

Keywords

PD-L1 expression

thymic epithelial tumors

thymoma

thymic carcinoma

SP142 antibody

SP263 antibody

immune checkpoint inhibitors

tumor immune evasion

histological categorization

treatment outcomes