Real‐World Safety Profile of Spesolimab in Generalized Pustular Psoriasis: Insights From Japan as Part of a Multinational Expanded Access Program ( <scp>EAP</scp> )

Generalized pustular psoriasis (GPP) is a heterogeneous, systemic neutrophilic inflammatory disease, characterized by chronic symptoms and recurrent flares, which can be potentially life-threatening. Spesolimab, an interleukin-36 receptor antagonist, has been approved to treat GPP flares in many countries including Japan. An expanded access program (EAP) in Japan provided early access to spesolimab for patients aged 18-75 years unable to participate in a clinical trial with no other treatment options. Patients received a single dose of 900 mg intravenous spesolimab for flare treatment, with an optional second dose after 1 week if symptoms persisted. Safety was monitored for 16 weeks post-treatment. Eleven patients (54.5% female; 51 years mean age; 26.7 kg/m² mean body mass index) received 23 doses of intravenous spesolimab. Nine patients (81.8%) were diagnosed with GPP for > 5 years. Ten patients (90.9%) had ≥ 1 baseline medical condition. All patients used ≥ 1 concomitant medication prior to or during the spesolimab treatment period, most commonly immunosuppressants and non-steroidal anti-inflammatory agents. Seven patients (63.6%) experienced treatment-emergent adverse events, all of mild or moderate intensity, including skin and subcutaneous tissue disorders, general disorders and administration site conditions. No adverse event led to treatment discontinuation or death. A potential hypersensitivity event (face edema) resolved without intervention and was not considered treatment related. Spesolimab was well tolerated in a heterogeneous patient population with GPP, including those with comorbidities and concomitant medication use. The safety profile of spesolimab aligned with the EFFISAYIL 1 clinical trial results.