Persistent anti-tumor response in cancer patients experiencing pneumonitis related to immune checkpoint blockade

Background: Immunotherapy in the form of immune checkpoint inhibition (ICI) is now well established as acornerstone for treating many advanced malignancies. Nevertheless, as the number of indications for checkpoint inhibitors increases, so does the risk of immune-related adverse events (irAEs). Methods: We report two patient cases who, after being treated by an anti-programmed cell death 1 (PD-1), presented with grade III dyspnea due to pneumonitis. Discussion: Immunotherapy was discontinued and the patients required treatment with systemic corticosteroids. At the time of writing, both patients are still in complete response (CR), more than 1year beyond immunotherapy discontinuation. We discuss our cases with regard to recent literature reports on immune-related pneumonitis and persistence of response beyond discontinuation.