Clinicopathologic Features of Thymoma With the Expression of Programmed Death Ligand 1

Abstract

Background. Programmed death ligand 1 (PD-L1) is reportedly expressed in various malignancies and is considered a prognostic factor. We attempted to reveal the usefulness of the PD-L1 expression as a prognostic factor in 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% or more of tumor cells was considered "positive." The association between the PD-L1 expression and the clinicopathologic features was investigated.Results. The PD-L1 expression was positive in 22 patients (27%) and negative in 59 patients (73%). The 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 than PD-L1 negative tumors (p [ 0.026). The 5-year disease-free survival rate was 82% in PD-L1 positive patients and 88% in PD-L1 negative patients, showing no significant difference (p [ 0.57). Furthermore, PD-L1 positivity was not an independent prognostic factor for the disease-free survival on a Cox proportional hazards analysis (p [ 0.59).Conclusions. A strong expression of PD-L1 in thymoma was significantly associated with type B2 and B3 and higher pathologic stages. In addition, PD-L1 positivity was associated with an increased maximum standardized uptake value of the tumor. However, patients with PD-L1 positive thymomas did not show a significantly worse prognosis than patients with PD-L1 negative tumors.

Clinicopathologic Significance and Immunogenomic Analysis of Programmed Death-Ligand 1 (PD-L1) and Programmed Death 1 (PD-1) Expression in Thymic Epithelial Tumors

“…High PD-L1 expression was correlated with higher Masaoka-Koga staging in six studies (21, 22, 27, 32, 34, 36) and associated with WHO classification of type B and/or thymic carcinoma in eight publications (22, 23, 27, 31, 32, 34–36). Most studies did not report differences in OS between the high and low PD-L1 expression groups ( n = 11) (16, 22, 24–27, 29, 30, 32, 33, 35), and three studies reported worse OS in the high PD-L1 expression group (21, 36, 37). In contrast, two studies reported better OS in the high PD-L1 expression group (24, 28).…”

Immune biomarkers in thymic epithelial tumors: expression patterns, prognostic value and comparison of diagnostic tests for PD-L1

“…Wei et al found no impact of PD-L1 expression on survival but high PD-L1 was associated with advanced Masaoka staging and high-grade histology in surgically treated thymoma [19] ). In two other studies, PD-L1 expression had no impact of PFS and 5 yr survival [18, 20] . In patients with advanced thymic carcinoma, the median PFS was higher in the low PD-L1 group vs the high PD-L1 group (23.5 vs 13.3 months) [21].…”

Prognostic and clinicopathological roles of programmed death‐ligand 1 (PD‐L1) expression in thymic epithelial tumors: A meta‐analysis

“…The analysis of the association between PD-L1 expression and overall survival (OS) included four studies with 555 TET patients. Hakiri et al 7 and Song et al 1 reported the HR in thymoma, Owen et al 8 in TC, and Wei et al 3 in both. This analysis was performed to include each HR reported in Wei et al 3 The pooled HR was evaluated using a fixed effect model (I 2 = 24.5%, P = 0.258).…”

“…6 Several studies have also shown an association between PD-L1 expression and prognosis of patients diagnosed with TETs. 1,3,4,[7][8][9] However, the association of PD-L1 expression with the prognosis of TETs has not yet been systematically analyzed.…”