P038 Guselkumab for pembrolizumab-induced psoriasis in a patient with metastatic melanoma

Abstract

A 61-year-old woman with long-standing plaque psoriasis, previously complicated by erythroderma, developed a severe flare following pembrolizumab for metastatic melanoma. Her initial melanoma arose on the right wrist (pT2a, cN3c), and treated with wide local excision and axillary clearance in 2022. She subsequently developed metastatic disease with hepatic and osseous involvement. Prior to commencing pembrolizumab, her psoriasis had been under excellent control with topical therapy alone. Following a single cycle of pembrolizumab, she developed an acute and rapidly progressive flare characterized by bright erythematous plaques with pustular features, intertriginous involvement and daily emergence of new psoriatic lesions. Palmoplantar hyperkeratosis and fissuring caused significant pain and impaired mobility (Psoriasis Area and Severity Index score of 12.3). Given the severity of disease, management required close multidisciplinary discussion between dermatology, oncology and hepatology. Systemic corticosteroids provided only transient benefit and were poorly tolerated. Acitretin was considered but was felt unsuitable due to underlying alcoholic liver cirrhosis and its prolonged half-life. Apremilast had previously been discontinued because of ­gastrointestinal intolerance. In view of ongoing morbidity and emerging literature supporting interleukin-23 blockade in psoriasis induced by immune checkpoint inhibitors (ICIs), guselkumab was commenced following a normal prebiologic screen. The patient demonstrated early clinical improvement with reduced inflammation and stabilization following steroid withdrawal, allowing pembrolizumab to be cautiously recommenced. Serial imaging demonstrated progression of metastatic disease, consistent with the natural history of advanced melanoma rather than clear treatment interference. ICI-associated psoriasis represents a challenging management dilemma, particularly in patients with advanced melanoma, where immunosuppression may compromise oncological outcomes. Only a small number of cases describing use of guselkumab in metastatic melanoma have been reported to date. This case adds to the growing evidence that interleukin-23 inhibition may offer effective psoriasis control while permitting continuation of life-prolonging immunotherapy in carefully selected patients.