Supplementary Material for: Fast itch relief during dupilumab predicts clinical efficacy in bullous pemphigoid, a retrospective cohort study

Introduction: Dupilumab has emerged as a promising treatment option for bullous pemphigoid (BP). Rapid identification of responders could avoid the need of additional immunosuppressive treatments that are associated with increased morbidity and mortality. Methods: To investigate the course of itch as an early indicator of treatment response, data of 12 BP patients treated with dupilumab at the University Hospital of Zurich were retrospectively evaluated. Disease severity was assessed by bullous pemphigoid disease area index (BPDAI) and pruritus by a numeric rating scale (NRS, 0-10) at baseline, day 1, 3, 14, month 1, 2 and last follow-up. Results: 8/12 patients (67%) had complete, and 4/12 patients (33%) had partial response during dupilumab treatment. Notably, a highly significant reduction of pruritus (p < 0.0001) was observed already on day 1 with further improvement at later time points. Moreover, fast relief of itch could predict treatment response with a significant correlation to clinical response on day 14 (Spearman correlation R 0.70, p-value 0.025), with a positive but non-significant trend on day 3 (R 0.63, p-value 0.091). Additionally, 92% (11/12 patients) were on dupilumab monotherapy at last follow-up without any concomitant systemic or topical treatment for BP. Conclusions: The rapid and significant decline in BP-associated pruritus observed with dupilumab correlated significantly with disease remission. Early evaluation of pruritus response could change how bullous pemphigoid is treated in the future and avoid additional immunosuppressive treatment in BP.