Sun Kyung Baek

Highlights • Pembrolizumab can cause rare but serious oral mucositis. • Combination therapy such as radiotherapy might enhance the degree of toxicity. • It should always be watched closely for unexpected and unknown side effects. Abstract Background Immune checkpoint inhibitors, such as pembrolizumab, a humanized monoclonal antibody against programmed death-1, elicit antitumor activity in various types of cancers, including lung cancer.