Association of immune checkpoint inhibitor-induced bullous pemphigoid with underlying cancer type: A lack of association with cancer tissue COL17A1 mutations and dysregulation

Bullous pemphigoid (BP) is an autoimmune blistering disease caused by autoantibodies to collagen type 17 (<i>COL17A1</i>) and is a recognized immune-related adverse event in patients receiving immune checkpoint inhibitors (ICIs). We investigated whether cancer type influences the risk of developing ICI-induced BP and whether <i>COL17A1</i> mutations or dysregulation in tumor tissue contributes to disease-specific variation. Using TriNetX, systematic review, and bioinformatics datasets, we comprehensively assessed the associations of ICI-induced BP with different malignancy types as well as <i>COL17A1</i> gene expression, mutation frequency, and immune correlations across cancers. Lung cancer was the most common underlying malignancy in ICI-induced BP, but nonmelanoma skin cancer and renal cell carcinoma had the highest relative risk, whereas lung cancer had the lowest. ICI-induced BP was associated with improved survival across several cancers. Urothelial cancer showed the shortest time to onset, whereas renal cell carcinoma showed the longest. Cutaneous squamous cell carcinoma and melanoma exhibited the highest <i>COL17A1</i> mutation burden, whereas renal cell carcinoma had a low burden. <i>COL17A1</i> was overexpressed in several cancers but underexpressed in melanoma, without strong correlation to tumor-infiltrating immune cells. Although the incidence of ICI-induced BP significantly differed on the basis of cancer type, <i>COL17A1</i> mutations or dysregulation do not appear to drive this phenomenon, suggesting alternative immune mechanisms.