Immune Checkpoint Inhibitor-Related Bullous Pemphigoid: Distinct Clinical and Immunological Profiles

Bullous pemphigoid (BP) induced by immune checkpoint inhibitors (ICI-BP) is a rare immune-related adverse event that affects patient prognosis and management; however, comparative data between ICI-BP and non-ICI BP, especially the dynamic changes of antibodies remain scarce. Therefore, we conducted this study to compare clinical presentation, immunological profile, treatment, management, and outcomes of ICI-BP versus non-ICI BP. This was a retrospective, single-centre cohort study of consecutive patients between 2019 and 2025. Patients with ICI-BP (Group A) were compared with Group B (BP with concurrent malignancy but no ICI exposure) and Group C (classic BP). There were 34, 10, and 68 patients enrolled in Groups A, B, and C, respectively (median follow-up 24.5 months, IQR 10.8-50.0). ICI-BP presented at a younger age (median, 59.0 years; IQR, 53.3-69.5; p < 0.001) and showed a marked male predominance (88.2%; p = 0.003). A transient, albeit non-significant, rise in anti-BP180 reactivity was observed during the first 2 months in ICI-BP. Systemic glucocorticoids were required more frequently in ICI-BP, and IL-4 inhibitors demonstrated superior potency in accelerating BP180 antibody decline compared to non-systematic therapy. Tumour response rates were similar between Groups A and B, as was mortality across the three groups. In conclusion, ICI-BP differs from non-ICI BP in clinical and immunological features and more often necessitates systemic glucocorticoid therapy, while IL-4 inhibitors potentially expedite the reduction of anti-BP180 antibodies in ICI-BP patients.