Clinical, Biological and Histological Characteristics of Bullous Pemphigoid Induced by antiPD-1/PDL-1 Therapy: A National Retrospective Cohort Study

All members of French study Group on Autoimmune Bullous Skin Diseases and French group of Onco-dermatology were asked to report cases of bullous pemphigoid induced by antiPD-1/PDL-1 therapy from 2014 to 2019. In this retrospective, observational cohort study, investigators included patients treated with PD-1 or PD-L1 inhibitor, with a diagnosis of bullous pemphigoid occurring during treatment or up to 12 months after its discontinuation. Diagnosis of BP was made by the dermatologist and was based on the following criteria developed by the French Bullous Study Group : compatible clinical presentation (absence of atrophic scars, absence of mucosal involvement and absence of predominant bullous lesions on the neck and head), compatible histopathology findings (subepidermal blister on skin biopsy; and linear deposits of IgG and C3 along the basement-membrane zone), positive DIF studies, positive enzyme-linked immunosorbent assay BP180/enzyme-linked immunosorbent assay BP230. For each case, collected data were : sex, type of tumor, type of checkpoint inhibitor, age at the onset of the checkpoint inhibitor, time from the onset of BP compared to the onset of the PD-1 inhibitor, clinical presentation of BP, results of complementary exams (skin biopsies, enzyme-linked immunosorbent assay for BP180 and BP230 and indirect immunofluorescence studies if available); treatment of BP used, consequence on antiPD-1/PD-L1 therapy, course of the tumor, other irAEs. Overall tumor response was determined by the treating oncologist and classified using RECIST 1.1 (Response Evaluation Criteria in Solid Tumors).