Immunotherapy and Checkpoint Inhibitors in Recurrent and Metastatic Head and Neck Cancer.

Immune surveillance is well recognized as an important mechanism to prevent development or progression of head and neck cancers. Head and neck cancer cells can escape the immune system through multiple mechanisms including development of tolerance in T cells and inhibition of T-cell-related pathways, generally referred to as checkpoint inhibitors. This article highlights advances in immuno-oncology treatment approaches in recurrent and metastatic head and neck squamous cell carcinoma. Clinical trials are discussed in detail, with an emphasis on response dynamics, oncologic efficacy, safety, and tolerability of checkpoint inhibitors. In addition, developing concepts and ongoing studies in this setting are also reviewed.