Immune checkpoint inhibitor-associated eosinophilic fasciitis: A FAERS pharmacovigilance analysis of a rare rheumatic immune-related adverse event.

Authors

Ze Wang, Hui Guo

Published in

Seminars in arthritis and rheumatism. Volume 80. Pages 153042. Jul 07, 2026. Epub Jul 07, 2026.

Abstract

Eosinophilic fasciitis (EF) is an uncommon rheumatic and connective tissue immune-related adverse event associated with immune checkpoint inhibitors (ICIs). Current evidence is limited to case reports and small case series. We investigated the association between ICIs and EF using the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS).
This retrospective pharmacovigilance study analyzed FAERS reports submitted from Q1 2011 to August 2025. In the primary analysis, EF was defined using the Preferred Term "Eosinophilic fasciitis." Sensitivity analysis used an expanded fibrosing/scleroderma-spectrum preferred term set including "Eosinophilic fasciitis" and "Scleroderma-like reaction." Eligible reports were restricted to cases in which the target ICI was coded as a primary or secondary suspect drug. Disproportionality was assessed using the reporting odds ratio (ROR), proportional reporting ratio (PRR), information component (IC), and empirical Bayesian geometric mean (EBGM). Demographic and clinical characteristics and time to onset were also evaluated.
A total of 69 reports of ICI-associated EF were identified in the primary analysis. Nivolumab accounted for the largest number of reports, followed by pembrolizumab and ipilimumab. The overall median age was 61 years, and the median time to onset was 319 days. ICIs as a class showed a strong positive signal for EF across all four algorithms (ROR 46.89, 95% CI 34.70-63.35). Anti-PD-1 agents showed a markedly stronger signal than anti-PD-L1 agents, and nivolumab and pembrolizumab showed the most robust signals among the more frequently reported agents. In sensitivity analysis, the number of reports increased to 83, while the overall direction of the findings remained stable, particularly for PD-1 inhibitors.
ICI-associated EF appears to be an uncommon but potentially serious delayed rheumatic immune-related adverse event. This FAERS analysis identified a strong pharmacovigilance signal linking ICIs to EF, with the most robust signals observed for PD-1 inhibitors, particularly nivolumab and pembrolizumab. Greater clinical awareness may facilitate earlier recognition of this fibroinflammatory toxicity and improve diagnostic and therapeutic management.

PMID:
42447599
Bibliographic data and abstract were imported from PubMed on 15 Jul 2026.

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