Expression of programmed cell death ligand 1 (PD-L1) and prevalence of tumor-infiltrating lymphocytes (TILs) in chordoma

• DOI: 10.18632/oncotarget.3576
• Publication Date: 2015-09-15T06:34:56Z
• Authors: Yong Feng; Jacson Shen; Yan Gao; Yunfei Liao; Gregory Cote; Edwin Choy; Ivan Chebib; Henry Mankin; Francis Hornicek; Zhenfeng Duan
• Keywords: PD-L1; Adult; Male; Blotting, Western; 610; B7-H1 Antigen; Immunoenzyme Techniques; 03 medical and health sciences; Lymphocytes, Tumor-Infiltrating; 0302 clinical medicine; 616; Chordoma; Prevalence; Tumor Cells, Cultured; Humans; TILs; chordoma; Aged; Neoplasm Staging; Aged, 80 and over; Middle Aged; Prognosis; 3. Good health; Survival Rate; Tissue Array Analysis; Female; immunotherapy; Neoplasm Recurrence, Local; Follow-Up Studies

Chordomas are primary malignant tumors of the notochord that are resistant to conventional chemotherapy. Expression of programmed cell death ligand 1 (PD-L1), prevalence of tumor-infiltrating lymphocytes (TILs), and their clinical relevance in chordoma remain unknown. We evaluated PD-L1 expression in three chordoma cell lines and nine chordoma tissue samples by western blot. Immunohistochemical staining was performed on a chordoma tissue microarray (TMA) that contained 78 tissue specimens. We also correlated the expression of PD-L1 and TILs with clinical outcomes. PD-L1 protein expression was demonstrated to be induced by IFN-γ in both UCH1 and UCH2 cell lines. Across nine human chordoma tissue samples, PD-L1 protein was differentially expressed. 94.9% of chordoma samples showed positive PD-L1 expression in the TMA. The expression score of PD-L1 for metastatic chordoma tumors was significant higher as compared with non-metastatic chordoma tumors. Expression of PD-L1 protein significantly correlates with the presence of elevated TILs, which correlates with metastasis. In summary, our study showed high levels of PD-L1 are expressed in chordoma, which is correlated with the prevalence of TILs. The current study suggests targeting PD-L1 may be a novel immunotherapeutic strategy for chordoma clinical trials.