Targeting the IL-36 Pathway: Spesolimab as a Therapeutic for Acute Flares of Pustular Psoriasis.

Generalized pustular psoriasis (GPP) is a rare and severe subtype of psoriasis characterized by widespread sterile pustules, erythema, and systemic inflammation. The condition is mediated by dysregulation of the IL-36 signaling pathway, which promotes excessive cytokine release and neutrophilic infiltration. Traditional therapies, including corticosteroids and immunosuppressive agents such as cyclosporine or methotrexate, often fail to achieve rapid or sustained disease control. Spesolimab, a monoclonal antibody that inhibits the IL-36 receptor, represents a novel targeted therapy approved for the treatment of acute GPP flares in adults. We describe a 56-year-old woman with no significant past medical history who presented with diffuse erythematous and scaly plaques involving the trunk, face, groin, and extremities. Initial biopsy findings were consistent with an eczematous dermatitis, and her eruption temporarily resolved with topical corticosteroids and a prednisone taper. Five months later, she developed diffuse pustules covering 80% of her body surface area (BSA), accompanied by fever, chills, and joint pain. A repeat biopsy demonstrated subcorneal neutrophilic pustules consistent with pustular psoriasis. She was treated with cyclosporine, resulting in partial improvement to 30% body surface area involvement. The patient subsequently received a 900 mg intravenous dose of spesolimab, which produced marked improvement within two weeks, leaving less than 5% body surface area involvement. Ongoing therapy with cyclosporine and planned monthly spesolimab infusions maintained disease remission. This case highlights the rapid efficacy and sustained control achieved with spesolimab in an acute flare of GPP refractory to conventional therapy. The results underscore the importance of IL-36 inhibition in targeting the underlying inflammatory pathway and suggest that early initiation of spesolimab may improve outcomes in patients with moderate-to-severe disease.