Immune checkpoint inhibitor-associated capillary leak syndrome: A systematic review and a worldwide pharmacovigilance study

Background: Although a few case reports have shown that immune checkpoint inhibitors (ICIs) are potential inducers of capillary leak syndrome (CLS), an incidental finding cannot be ruled out. The aim of this study was to describe the clinical characteristics of ICI-induced CLS through a systematic review and to assess a potential safety signal.

Methods: Medline/PubMed, Embase, and Reactions Weekly were screened, and a global disproportionality study was performed using the World Health Organization pharmacovigilance database through January 15, 2023. A signal of disproportionate reporting was defined as a Bayesian information component (IC) with a 95% credibility interval (CrI) lower boundary that exceeds 0.

Results: A total of 47 cases of ICI-associated CLS were included, 14 from the systematic review (of 61 screened articles) and 33 from VigiBase (of 34,058,481 reports of adverse drug reactions). The median time to CLS onset from the start of ICI was 12 weeks (interquartile range 8-49, n = 24). A total of 57% (8/14) of patients experienced an immune-related adverse event (irAE) before CLS. A fatal outcome was reported in 23% (7/31) of patients. A significant overreporting of CLS was found with ICIs compared with all other drugs (IC 2.4, 95% CrI from 1.8 to 2.8).

Conclusion: This study showed a significant signal of disproportionality reporting for ICI-induced CLS, characterized by a long time to onset, and compared with the idiopathic form of the disease with a less abrupt onset and a less consistent hemoconcentration pattern.