From ICI to ICU: A systematic review of patients with solid tumors who are treated with immune checkpoint inhibitors (ICI) and admitted to the intensive care unit (ICU).

Purpose: Immune checkpoint inhibitors (ICIs) have improved the survival of patients with different solid tumors and even resulted in cure of metastatic disease. Since the introduction of ICIs, an increasing number of patients is admitted to the ICU for severe and potentially life-threatening immune related adverse events (irAEs). The outcome of patients who are admitted to the ICU because of severe irAEs is still unknown. The aim of this systematic review is to collect evidence on the outcomes of patients with solid tumors who are admitted to the ICU because of irAEs.

Methods: Medline, Embase, Cochrane central register of controlled trials and Google Scholar were searched systematically from 1975 to 24 September 2024. Articles were only included when describing patients with solid tumors who were admitted to the ICU because of irAEs after treatment with ICIs. Two independent reviewers extracted the data and assessed the risk of bias.

Results: A total of 183 articles were included: two prospective ICU population-based studies, four retrospective ICU population-based studies, 25 retrospective studies describing irAEs with incidental ICU admissions, one review of case reports, and 153 articles with a total of 177 case reports. The six ICU population-based studies contained a total of 169 patients who were admitted to the ICU due to irAEs. In these six studies, the most frequently reported irAEs were pneumonitis and neurological irAEs. Of these 169 patients, 26% of the patients died on the ICU and an additional 8% of patients in the three to six months thereafter due to irAEs or disease progression. In all 183 included articles, various irAEs were described and the reported mortality rate varied from 0 to 53%.

Conclusion: The potential favorable outcomes of both the solid tumors and irAEs will probably result in more need for ICU admissions. Prospective clinical trials are needed to optimize the treatment strategy of severe irAEs at the ICU. Based on the favourable outcomes after life-threatening irAEs, ICU admission should definitely be considered for patients with solid tumors who have life-threatening irAEs.