Clinicopathological Features of Thymoma with the Expression of Programmed Death-Ligand 1

Date 20 October 2018
Event ESMO 2018 Congress
Session Poster display session: Biomarkers, Gynaecological cancers, Haematological malignancies, Immunotherapy of cancer, New diagnostic tools, NSCLC - early stage, locally advanced & metastatic, SCLC, Thoracic malignancies, Translational research
Topics Tumour Immunology
Pathology/Molecular Biology
Thymoma and Thymic Cancer
Presenter Shuhei Hakiri
Citation Annals of Oncology (2018) 29 (suppl_8): viii641-viii644. 10.1093/annonc/mdy301
Authors S. Hakiri1, T. Fukui1, S. Mori1, K. Kawaguchi1, S. Nakamura1, N. Ozeki1, T. Kato1, M. Goto1, Y. Yatabe2, K. Yokoi1
  • 1Thoracic Surgery, Nagoya University, Graduate School of Medicine, 466-8550 - Nagoya/JP
  • 2Pathology And Molecular Diagnostics, Aichi Cancer Center Hospital, 464-8681 - Nagoya/JP

Abstract

Background

Programmed death-ligand 1 (PD-L1) is reportedly expressed in various malignancies and is considered a prognostic factor. We attempted to characterize the association between the PD-L1 expression and the clinicopathological features of patients with thymoma.

Methods

Eighty-one patients with thymoma who underwent surgical resection between 2004 and 2015 were retrospectively reviewed. The PD-L1 expression was evaluated by immunohistochemistry and stratified by the proportion of positive tumor cells. Strong membranous reactivity of the PD-L1 antibody in ≥ 1% of tumor cells was considered ‘positive’. The association between the PD-L1 expression and the clinicopathological features was investigated.

Results

The PD-L1 expression was positive in 22 patients (27%) and negative in 59 patients (73%). PD-L1 positivity was significantly associated with type B2 and B3 thymoma (p < 0.001) and stage III and IV disease (p = 0.048). In addition, PD-L1-positive tumors showed a significantly higher maximum standardized uptake value (SUVmax) than PD-L1-negative tumors (p = 0.026). The 5-year disease-free survival (DFS) rate was 83% in PD-L1-positive patients and 88% in PD-L1-negative patients, showing no significant difference (p = 0.576). Furthermore, PD-L1 positivity was not an independent prognostic factor for the DFS on a Cox proportional hazard analysis (p = 0.590).

Conclusions

A strong expression of PD-L1 in thymoma was significantly associated with type B2 and B3 and higher pathological stages. In addition, PD-L1 positivity was associated with an increased SUVmax of the tumor. However, patients with PD-L1-positive thymomas did not show a significantly worse prognosis than those with PD-L1-negative tumors.

Clinical trial identification

Legal entity responsible for the study

Department of Thoracic Surgery, Nagoya University Graduate School of Medicine.

Funding

Has not received any funding.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.