Near complete response to a pembrolizumab-based therapeutic strategy in an abdominal metastatic head and neck squamous cell carcinoma case.

Metastasis of head and neck squamous cell carcinoma rarely occurs in hepatic cancer and has a poor prognosis (median survival of 4 months). The efficacy of immunotherapy for these patients remains unknown. Herein, we present a patient with hypopharyngeal carcinoma metastasis to the liver with TERT and TP53 mutations together with a combined positive score of 70. The tumor invaded the abdominal wall, liver, inferior vena cava and retroperitoneal lymph nodes. The patient was treated with pembrolizumab combined with cisplatin and 5-FU for four cycles and has been maintained on pembrolizumab monotherapy until now. The patient achieved a near complete response of hepatic and subcutaneous metastases, and the tumor thrombus disappeared completely. The patient developed grade I rashes on the trunk, which were considered immune-related adverse events; thus, the patient presented a significant tumor response and good tolerance to the therapeutic strategy. On the basis of this observation, pembrolizumab-based therapeutic strategies may be an effective alternative for metastatic hypopharyngeal carcinoma and may prolong overall survival and progression-free survival, which should be confirmed by more patients in the future. Immune-related adverse events also need attention.