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Yi-Ting Yen
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MA 16 - Mediastinal, Tracheal and Esophageal Tumor: Multimodality Approaches (ID 675)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Thymic Malignancies/Esophageal Cancer/Other Thoracic Malignancies
- Presentations: 1
- Moderators:K. Shibuya, Francoise Mornex
- Coordinates: 10/17/2017, 15:45 - 17:30, Room 313 + 314
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MA 16.02 - Different Pattern and Prognostic Role of PD-L1, IDO, and Foxp3 Treg Expression in Thymoma and Thymic Carcinoma (ID 8796)
15:50 - 15:55 | Presenting Author(s): Yi-Ting Yen
- Abstract
- Presentation
Background:
The immune checkpoint ligand programmed cell death 1 ligand (PD-L1) is expressed in various tumors, and the expression of indoleamine 2,3-dioxygenase (IDO) and Foxp3 Tregs are associated with tumor-induced tolerance and reported to be responsible for worse survival. Their prognostic role in thymoma and thymic carcinoma, however, has not been investigated.
Method:
A tissue microarray comprised of 100 surgically treated thymomas and 69 surgically treated thymic carcinomas was evaluated. PD-L1, IDO, and Foxp3 Treg staining was scored based on intensity as follows: 0 = none, 1 = equivocal/uninterpretable, 2 = weak, and 3 = intermediate-strong. The PD-L1, IDO, and Foxp3 Treg expression score was calculated using a semiquantitive method by multiplying the intensity [0-3] by the staining area [0-100%]. Those cases with all cores scoring three and 2 in more than 50% in the staining area were categorized as PD-L1, IDO, and Foxp3 Treg high expression and the remaining as low expression. Clinical information was also collected on age, sex, Masaoka staging, tumor histology, surgical radicality, and locoregional invasion. Statistical associations were evaluated using χ[2] test and Fisher’s exact test. Progression-free survival and overall survival curves were established by the Kaplan-Meier method and compared using a log-rank test.
Result:
Figure 1Figure 2Thirty-six (36%) thymoma and 25 (36%) thymic carcinoma cases revealed high expression of PD-L1. PD-L1 expression in thymoma is significantly associated with Masaoka staging (p<0.001), tumor histology (p<0.001). Although there was a trend toward worse progression-free and overall survival in thymoma and thymic carcinoma with high-expression of PD-L1, only the progression-free survival in thymoma was significantly worse (p=0.024). High expression of IDO was detected in 13 (13%) thymoma and 10 (14%) thymic carcinoma cases, whereas Foxp3 Treg was detected in 16 thymoma (16%) and 20 (29%) thymic carcinoma cases. The expressions of IDO and Foxp3 Treg were significantly associated with tumor histology in thymoma (p=0.002 and 0.016, respectively), but not in thymic carcinoma. Thymic carcinoma with high expression of IDO had a trend toward worse progression-free and overall survival trend (p=0.109 and 0.053, respectively). High expression of Foxp3 Treg, however, was significantly associated with better progression-free survival (p=0.006) and overall survival (p=0.007) in thymic carcinoma.
Conclusion:
This is the largest-scale study to evaluate PD-L1 expression in thymic epithelial tumors. Although high expression of PD-L1 might be associated with worse prognosis in thymoma and thymic carcinoma, further investigation into PD-L1, IDO, and Foxp3 Treg should be conducted to benefit anti-PD-L1 immunotherapy for thymic epithelial tumor.
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