Investigation of HEG1, VISTA (VSIR) and PD-L1 expression levels in malignant mesothelioma by immunohistochemical methods and their relationship with histological subtypes

Abstract

Malignant Mesothelioma is a primary malignant tumor of the mesothelium lining the pleura, pericardium, peritoneum and tunica vaginalis of the testis with a poor prognosis. The epithelioid subtype is graded as high and low grade in the 2021 WHO classification of thoracic tumors. Recently, promising results from clinical trials of treatment with immune checkpoint inhibitors are reported. The aim of our study was to shed light on clinical studies on potential immune checkpoint inhibitors by examining VISTA and PD-L1 expression levels as well as HEG1 in malignant mesothelioma subtypes. Our study included 69 cases diagnosed with ‘malignant mesothelioma, well-differentiated papillary mesothelial tumor, atypical mesothelial hyperplasia’ at Dicle University Faculty of Medicine Department of Pathology between 2015 and 2021. Primary antibodies against HEG1, VISTA, and PD-L1 were used in the immunohistochemical study. The results showed a significant relationship between PD-L1 expression and sarcomatoid and high-grade epithelioid malignant mesotheliomas. VISTA was detected at a high rate in epithelioid malignant mesotheliomas and was negative in non-mesothelial tumors. HEG1 was positively monitored in mesothelial-derived tumors and negatively monitored in non-mesothelial tumors. The obtained results suggest that HEG1 could be further explored as a useful marker in determining mesothelial origin and that the expression levels of VISTA and PD-L1 markers may vary in histological subtypes in the selection of drugs for the treatment of malignant mesothelioma.

Keywords:

• Mesothelioma
• HEG1
• VISTA
• pd-l1

Acknowledgments

The study was reported as a presentation at the 35th European Congress of Pathology in 2023. [Dicleli M, Keleş A. E-PS-25-001 HEG1 expression in mesothelial tumours. In: 35th European Congress of Pathology – Abstracts. Virchows Arch. 2023;483 (Suppl 1), https://doi.org/10.1007/s00428-023-03602-w.

Authors’ contributions

All authors contributed significantly to the work and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. MD and UA made substantial contributions to the conception and design of the work. MD, ANK, and UA were involved in project management, literature search, data acquisition, interpretation, drafting, and reviewing of the manuscript. ANK and UA were involved in visualization. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [UA], upon reasonable request.

Additional information

Funding

This study was supported by SBE.21.006 code number, was conducted at the Scientific Research Projects Unit of Dicle University.