HLA-I and PD-L1-expression in oropharyngeal squamous cell carcinoma – Influence on survival by immune escape?

Introduction:

In the etiology of oropharyngeal squamous cell carcinoma, human papillomavirus (HPV) plays an increasing role. In particular, the balance between a sufficient immune-response and selective blocking of the immune system can contribute to regression or progression of cancer. We investigated the role of aberrant HLA (human leucocyte antigen)-, and PD-L1 (programmed death ligand 1)-expression on cell surface of oropharyngeal squamous cell carcinoma (OPSCC) as a function of HPV-status.

Methods:

FFPE tissue samples of 207 patients with OPSCC were used to generate tissue micro array. Slices were immunohistochemically stained and subsequently evaluated for HLA- and PD-L1-expression. Expression rates were correlated with clinical data and evaluated statistically.

Results:

HLA I-expression was less common in HPV-associated than in HPV-negative OPSCC (47% vs. 73%, p = 0.005). No significant difference was observed analyzing overall survival in dependence of HLA-expression (p = 0.267). PD-L1-expression was associated with improved 5-year overall survival in all patients with OPSCC (62% vs. 33%, p = 0.001). Higher rates of PD-L1 were observed in HPV-associated compared to HPV-negative OPSCC (73% vs. 33%, p < 0.001), whereas this was not associated with improved overall survival in patients with HPV-associated OPSCC.

Conclusion:

Significantly reduced HLA-I- and elevated PD-L1-expression rates were detected in HPV-associated OPSCC. These results point to an immunosuppressive phenotype related to the HPV-association of these tumors.

Publication History

Publication Date:
18 April 2018 (online)