The biology of combination immunotherapy in recurrent metastatic head and neck cancer

Preclinical data suggest that head and neck cancer is an intrinsically immunosuppressive disease with abnormal inflammatory components in the tumor microenvironment. The development of immune checkpoint inhibitors, which are monoclonal antibodies capable of inhibiting immune suppressive signals to prime anticancer immunity, has revolutionized the therapeutic landscape in recurrent/metastatic head and neck cancer. However, patients with head and neck cancer present primary resistance to immunotherapy. Many ongoing trials include combinations of immunotherapy with different therapeutic interventions, aiming to improve response rates and overall survival. As novel therapy strategies are leveraged, the significance of immunotherapy in recurrent/metastatic head and neck cancer continues to be revealed. This review aims to summarize combinational immunotherapy in head and neck cancer.