British Society for Skin Care in Immunosuppressed IndividualsOral presentationsBI01 Persistent nonpruritic scabies in a patient on nemolizumab for the treatment of prurigo nodularis

Abstract Nemolizumab is a humanized monoclonal antibody that blocks interleukin (IL)-31 signalling through binding to IL-31 receptor alpha. IL-31 is a key itch cytokine and nemolizumab has proven effective at reducing pruritus and objective skin signs in atopic dermatitis and nodular prurigo. We present the case of a 38-year-old man with severe nodular prurigo who achieved complete skin clearance with no itch on nemolizumab as part of a clinical trial but developed persistent scabies on therapy. The patient was part of the OLYMPIA 1 trial ((NCT04501666) and long-term extension (NCT04204616), with nemolizumab dosed every 4 weeks. At week 132 this patient presented with a nonpruritic widespread erythematous papular rash on his feet, hands and trunk. This was initially treated as a mild eczema with topical steroids for 4 weeks, to minimal benefit. Repeat examination revealed lichenified papules on the instep of both feet and burrows with dermoscopic evidence of mites, confirming a diagnosis of scabies. The patient did not respond to monotherapy with topical permethrin 5% (and standard hot wash measures) and required a combination of oral ivermectin and topical permethrin 5% for complete clearance. He reported no household contacts and no affected family or friends. Despite complete clearance post-treatment, he developed a recurrence of the infestation 32 weeks later at week 164 and was successfully re-treated with the above regimen. The complete absence of associated pruritus (a primary hallmark of the disease) was likely a result of nemolizumab treatment. This potentially delayed presentation and diagnosis and resulted in a high mite burden and the need for repeat treatment. This case supports an important role for IL-31 in scabies-related pruritus and highlights one potential mechanism through which the often intolerable itch may be controlled. IL-31 has previously been shown to be overexpressed in scabies-affected skin as part of a predominant T helper 2 immune response (Hashimoto T, Satoh T, Yokozeki H. Pruritus in ordinary scabies: IL-31 from macrophages induced by overexpression of thymic stromal lymphopoietin and periostin. Allergy 2019; 74: 1727–37). It is important to consider the potential absence of pruritus in patients on nemolizumab when assessing new cutaneous and systemic presentations, particularly in the context of a rising prevalence of scabies in the UK.