Evolving Role of Immunotherapy in Recurrent Metastatic Head and Neck Cancer.

Immunotherapy has revolutionized cancer treatment in the past 2 decades, mostly with immune checkpoint blockade approaches. In squamous cell carcinoma of the head and neck (SCCHN), the initial efficacy of immunotherapy was observed in patients with recurrent or metastatic (R/M) disease who received other prior systemic treatment. As monotherapy, anti-PD-1 therapies induce responses in 13% to 18% of patients. More recently, immunotherapy in combination with cytotoxic chemotherapy demonstrated greater safety and efficacy as first-line systemic treatment compared with chemotherapy alone. In R/M SCCHN, the most important benefit of immunotherapy is the significantly improved overall survival, especially in patients with PD-L1-positive tumors. As of 2019, immunotherapy can be used as first-line or subsequent treatment of R/M SCCHN. Many ongoing trials are evaluating immunotherapy combinations or novel immunotherapy strategies, aiming to improve response rate and overall survival. As new targets are identified and new approaches are leveraged, the role of immunotherapy in R/M SCCHN continues to evolve.