Durable response to nivolumab in combination with regional hyperthermia in a patient with PD-L1-negative metastatic head and neck squamous cell carcinoma.

We report a long-lasting response to the immune checkpoint inhibitor nivolumab in combination with regional hyperthermia (RHT) in a patient with recurrent metastatic Head and Neck Squamous Cell Carcinoma (HNSCC) and negative programmed death ligand 1 (PD-L1) expression. Treatment was well tolerated with no local side effects. Tumor-related symptoms in the orbital and masticator area gradually decreased under treatment with nivolumab and RHT. Over the course of treatment, magnetic resonance imaging (MRI) showed a local tumor control in the heated tumor areas, while metastatic lesions developed in areas outside of the RHT field. This is the first case report demonstrating the feasibility and clinical potential of the addition of RHT in this patient collective with poor outcomes and low response rates to immune checkpoint inhibitors. RHT might be an additional tool to activate an immunogenic milieu responsive to immune checkpoint inhibitors.