Evaluation of Programmed Death Ligand 1 Immunohistochemistry in Cytology Specimens of Head and Neck Squamous Cell Carcinoma

摘要

Immune checkpoint inhibitors (ICIs) have emerged as treatment options for patients affected by head and neck squamous cell carcinoma (HNSCC). Currently, the programmed cell death protein 1 (PD-1) inhibitors pembrolizumab (Keytruda) and nivolumab (Opdivo) are approved by the Food and Drug Administration for the management of recurrent and/or metastatic (R/M) HNSCC. Unfortunately, it is estimated that 70% to 90% of patients with R/M HNSCC have no response to ICIs or show disease progression after an initial response. Therefore, the clinical assessment of biomarkers to predict which patient will benefit from ICI therapy is important. In that context, the KEYNOTE-048 study showed that monotherapy with pembrolizumab is an appropriate first-line treatment for programmed death ligand 1 (PD-L1)—positive cases in comparison with cetuximab in combination with chemotherapy. This led to the Food and Drug Administration's approval of pembrolizumab in patients with R/M HNSCC who have not received prior treatment with platinum-based chemotherapy for their R/M disease, and PD-L1 testing by immunohistochemistry using the Dako PD-L1 clone 22C3 pharmDx is now considered the standard of care in this setting.