Expression of programmed cell death ligand 1 (PD-L1) and prevalence of tumor-infiltrating lymphocytes (TILs) in chordoma
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Yong Feng1,2, Jacson Shen1, Yan Gao1, Yunfei Liao1,3, Gregory Cote4, Edwin Choy4, Ivan Chebib5, Henry Mankin1, Francis Hornicek1 and Zhenfeng Duan1
1 Sarcoma Biology Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital and Harvard Medical School, Jackson, Boston, Massachusetts, USA
2 Department of Orthopaedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
3 Department of Endocrine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
4 Division of Hematology and Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
5 Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
Zhenfeng Duan, email:
Keywords: PD-L1, TILs, chordoma, immunotherapy
Received: February 04, 2015 Accepted: February 21, 2015 Published: March 14, 2015
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.
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