Poor survival of metastatic cancer patients hospitalized due to immune checkpoint inhibitor-related adverse events

Immune-related adverse events (irAEs) are common side effects of immune checkpoint inhibitor (ICI) cancer therapy, affecting approximately half of ICI-treated patients. irAEs may be severe and result in hospitalization. This study examined the risk factors and outcomes of irAE-related hospitalization. We conducted a retrospective study including 202 metastatic cancer patients treated with ICIs at Kuopio University Hospital, Finland, in 2015–2022. IrAEs occurred in 57.4% of the patients. About 26.0% of them required inpatient treatment. Hospitalization was associated with severe (grades III – IV) toxicities and need for systemic corticosteroids. Median overall survival (mOS) for hospitalized patients was 12.9 months and for outpatients with irAEs 26.9 months (<i>p</i> = 0.006). The duration of ICI therapy was 1.8 months in hospitalized patients and 5.0 months in outpatients (<i>p</i> &lt; 0.001). The median maximum glucocorticoid doses were 52 mg and 100 mg, respectively (<i>p</i> &lt; 0.001). IrAE-related hospitalization deteriorated the survival of ICI-treated patients, likely due to decreased biological efficacy of ICIs resulting from short therapy periods and strong immunosuppression by glucocorticoids. Immune-related adverse events (irAEs) are common in cancer patients receiving immune checkpoint inhibitor (ICI) therapy. Some of these side effects can be severe and require hospital treatment. In this study, 26% of patients that developed an irAE were admitted to hospital. Patients who were hospitalized had more severe toxicities and needed high-dose corticosteroids for the treatment of irAEs. Survival was shorter for hospitalized patients, 12.9 months, compared to those with side effects who were not hospitalized, 26.9 months. This is likely attributed to shorter ICI therapy periods and high corticosteroid doses that may suppress the ICI therapy efficacy. Therefore, hospitalization due to an irAE may be a poor prognostic factor for patients treated with ICIs.