PD-L1 testing and immunotherapy selection – early laboratory experience and its potential role in head and neck cancer management

Anti-programmed cell death protein-1 (PD-1) therapy has been relatively recently approved in a defined context by NICE in adults in the management of recurrent and metastatic head and neck squamous cell carcinomas (HNSCC). In this context, companion diagnostic programmed cell death ligand-1 (PD-L1) testing, previously established at our center for lung and bladder tumors, was undertaken in a few head and neck cancer cases. The scope of this study was to audit the relevant PD-L1 data and integrate the findings in our current clinical practice, with a view to promote improved routine laboratory biomarkers in HNSCC.  Histopathology reports documenting tumor type, PD-L1 result and type of clone/assay were included in this study. Over a 5-year period, PD-L1 testing was undertaken in 199 cancer cases, including 3 with head and neck squamous carcinoma with low focal positive staining. Immunotherapy treatment in HNSCC demonstrates a discreet but still significant improvement in the overall survival of PD-L1 positive subjects.