PD‐L1 expression patterns in oral cancer as an integrated approach for further prognostic classification

• Published in: Oral diseases 2021-10, Vol.27 (7), p.1699-1710
• Main Authors: Miranda‐Galvis, Marisol, Rumayor Piña, Alicia, Sales de Sá, Raísa, Almeida Leite, Amanda, Agustin Vargas, Pablo, Calsavara, Vinicius Fernando, Lópes Pinto, Clóvis A., Teng, Yong, Kowalski, Luiz Paulo
• Format: Article
• Language: English
• Subjects: Antitumor activity; Apoptosis; B7-H1 Antigen; Biomarkers; Carcinoma, Squamous Cell; Cell death; expression pattern; Head and Neck Neoplasms; Humans; immune microenvironment; Immune response; Immunohistochemistry; Interfaces; Localization; Mouth Neoplasms; Oral cancer; Oral carcinoma; Oral squamous cell carcinoma; PD-L1 protein; Prognosis; programmed cell death ligand 1; Retrospective Studies; Risk factors; score; Squamous cell carcinoma; Tumor cells; Tumor Microenvironment
• ISSN: 1354-523X; 1601-0825
• DOI: 10.1111/odi.13714

Background Despite the well‐known role of programmed cell death ligand 1 (PD‐L1) in promoting immune resistance in oral squamous cell carcinoma (OSCC), its potential utility as a prognostic biomarker is undetermined. We evaluated PD‐L1 expression as predictor of survival in patients with OSCC and explored PD‐L1 expression patterns. Methods We conducted a retrospective cohort study that assessed PD‐L1 expression through immunohistochemistry in 123 surgical specimens of OSCC. A first approach evaluated tumor proportion scores (TPS) and combined proportion scores (CPS). Next, expression patterns were examined by evaluating PD‐L1 localization in tumor nests, as well as the interfaces of tumor cells (TC) and immune cells (IC) in the tumor microenvironment. Results High‐level PD‐L1 expression determined by TPS and CPS using variable cutoffs was not associated with survival. Immunohistochemistry revealed that TC expressed PD‐L1 in either patchy or diffuse patterns. The patchy pattern was an independent risk factor for overall survival. Furthermore, expression patterns in the tumor immune microenvironment showed that most cases expressed PD‐L1 on both TC and IC, while PD‐L1 non‐expressors had the lowest overall survival. Conclusion PD‐L1 expression patterns in the context of localization in tumor nests and TC—IC interactions represent antitumor immune responses better than either TPS or CPS. Our suggested classification system may have important implications for the characterization of OSCC and for the use of PD‐L1 as a prognostic biomarker.