PD-L1 expression in head and neck cancer – Variability, prognostic value and therapeutic relevance

Introduction The PD-L1-related immune escape of head and neck tumor cells is known as a mechanism of tumor proliferation, but the increased expression of PD-L1 in the tumor appears to be a prognostic factor dependent on the tumor entity. Accordingly, the relevance of PD-L1 in head and neck squamous cell carcinoma (HNSCC) has not been clearly clarified. In particular, the question of the homogeneity of the marker within the tumor and in the comparison of tumor and metastasis arises.

Methods In a group of 30 patients with metastatic squamous cell carcinoma of the oropharynx, PD-L1 was determined in tumor and metastasis using immunohistochemical staining on Tissue Micro Arrays (TMA). Expression was compared between tumor and corresponding metastasis.

Results PD-L1 expression in the primary tumor and corresponding metastasis was found in 13 out of 30 patients (43%), with a lack of expression in 11 out of 30 patients (37%). In 6 patients there was a discrepancy in expression between primary tumor and metastasis.

Conclusion The approved immunotherapy of HNSCC in the metastatic / recurrent tumor stage by antibody-mediated PD-1 inhibition is essentially based on PD-L1 expression in the tumor in its therapy recommendations. However, this and other studies prove the inhomogeneity of PD-L1 in tumor and metastasis. Furthermore, the dependence of expression on radio- or chemotherapeutic pre-treatment must be critically scrutinized on the basis of current literature. The optimization of a marker constellation with improved prognostic value with regard to the response to PD-1 antibody therapy should therefore be the goal of further investigations.

Publication History

Article published online:
19 April 2024