Paradoxical phenomena of bullous pemphigoid induced and treated by identical biologics.

Objective: This study aimed to investigate the clinical features of biologics-induced bullous pemphigoid (BP) and the therapeutic effects of those agents for BP, exploring the underlying pathophysiological mechanisms. Methods: We searched PubMed, Web of Science, and Elsevier for studies involving pemphigoid patients treated with or induced by identical biologics published in English from January 2009 to April 2022. Results: Seventeen cases of drug-induced BP associated with anti-tumor necrosis factor (aTNF)-α therapies, one with interleukin (IL)-17 inhibitors, and seven with IL-12/IL-23 or IL-23 inhibitors were enrolled. Time to cutaneous toxicity varied among different types of agents, and the characteristics of clinical examinations were similar to idiopathic BP. Discontinuation of the culprit drugs and initiation of topical or systemic corticosteroids were adequate in most cases. Several monoclonal antibodies above have also been reported for the treatment of refractory or recurrent BP, especially concurrent with psoriasis. Conclusion: Biologics for immune-related diseases, including TNF-α, IL-17, and IL-12/IL-23 or IL-23 inhibitors, can both induce and treat BP, which might be associated with a helper T cells Th1/Th2 imbalance, complicated inflammatory networks, and a specific individual microenvironment, suggestive of a new perspective on the therapeutic algorithms of BP. There have been numerous reports about biologics inducing or treating BP. We have taken note of this phenomenon and focused on biologics with both pathogenetic and therapeutic effects on BP. Our review summarized the clinical characteristics of associated cases, trying to figure out the underlying mechanisms of this paradoxical phenomenon and to provide an integrated perspective and new therapeutic alternatives for BP.