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MINI 24 - Epidemiology, Early Detection, Biology (ID 140)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
MINI24.12 - Assessment of PD-L1, TGF-β Expression and Tumor-Infiltrating CD8+ T Cells in Advanced Thymic Epithelial Tumors (ID 2373)
16:45 - 18:15 | Author(s): H. Chen
“Avoiding immune destruction” is one of the emerging hallmarks of cancer, as proposed by Weinburg and Hanahan. High expressions of immunosuppresive proteins strongly links to prognosis and cancer treatment. This study aimed to exam the expressions of immunosuppressors programmed death receptor ligand-1 (PD-L1) and transforming growth factor –β (TGF-β), and CD8+ tumor-infiltrating lymphocytes (TILs) in pre-treatment specimens from patients with advanced thymic epithelial tumors (TETs) including advanced thymic carcinoma and advanced invasive thymoma. To our knowledge, this is the first report to demonstrate the expression of PD-L1, TGF-β and CD8 and their clinical relevance in advanced TETs in Chinese population.
Retrospective analysis was performed using tumor specimens from 20 patients with stage IV thymic carcinoma and 13 patients with stage III/IV invasive thymoma. Tissue biopsies were obtained before the first-line chemotherapy with (or without radiotherapy). The expression level of PD-L1, TGF-β and the prevalence of CD8+ TILs were assessed using immunohistochemistry (IHC). Their prognostic value for predicting overall survival (OS) and progression-free survival (PFS) were statistically analyzed using the SPSS software.
Higher expression levels of PD-L1 and TGF-β were detected in advanced thymic carcinoma than in advanced invasive thymoma (65.0% vs. 46.2%, 65.0% vs. 15.4%, respectively). Low level of CD8+ TILs was presented in 45.0% cases with advanced thymic carcinoma. In advanced thymic carcinoma, higher TGF-β expression was strongly associated with worse OS, with a p-value almost reaching statistical significance (p = 0.052). Median OS of patients with TGF-β high and low expression was 29.5 ms (95%CI: 18.6-40.4) and 62.9 ms (95%CI: 15.6-110.1), respectively. Higher PD-L1 expressions significantly predicted worse PFS after firs-line chemotherapy with (or without) radiotherapy (p =0.043). Median PFS was not estimable in PD-L1 low expression group. Mean PFS of patients with PD-L1 high and low expression was 13.3ms (95%CI: 8.0-18.6) and 23.5ms (95%CI: 13.9-33.2), respectively. An additional radiation treatment was particularly needed for CD8 low expression patients, in which first-line treatment with “chemotherapy + radiotherapy” significantly prolonged PFS compared to “chemotherapy-alone” (median PFS = 6.8ms, 95%CI: 0.0-2.7 vs. 3.5ms, 95%CI: NE, p = 0.015).
Our results documented the clinical relevance of PD-L1, TGF-β, and CD8 in advanced TETs, with the prognostic value of predicting OS and PFS, as well as a potential association of immune conditions with therapeutic benefits.
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