Spesolimab, the first‐in‐class anti‐IL‐36R antibody: From bench to clinic

Abstract Inflammatory diseases that are driven by several pro‐inflammatory cytokines has resulted in in the development of targeted therapies across different disease settings. Interleukin (IL)‐36 cytokines have been implicated in several inflammatory diseases. In this review we describe the scientific evidence surrounding the use of the IL‐36 receptor (IL‐36R)‐targeting antibody, spesolimab, in IL‐36‐mediated skin diseases: generalized pustular psoriasis (GPP), palmoplantar pustulosis (PPP), hidradenitis suppurativa, and Netherton syndrome (NS). Spesolimab, a high affinity, specific, humanized, antagonistic immunoglobulin G1 antibody, targets the IL‐36R at a binding site distinct from its agonists, IL‐36α/β/γ, and at least one endogenous antagonist, IL‐36R antagonist. In vitro and in vivo data for spesolimab show effective inhibition of IL‐36R‐mediated signaling pathways, and six Phase I studies in healthy volunteers presented a favorable safety and pharmacokinetic (PK) profile, leading to the development of a clinical trial program to evaluate spesolimab in the treatment of IL‐36R‐mediated diseases. Six studies (including an expanded access program) have evaluated the efficacy, safety, PKs, and pharmacogenomics of spesolimab in patients with GPP flares. Spesolimab treatment of GPP flares resulted in rapid and sustained improvements in pustular and skin clearance, and clinically significant improvements in patient‐reported symptoms and quality of life. Spesolimab also significantly reduces the risk of GPP flares and flare occurrence, preventing disease worsening and has a favorable safety profile. There have been three trials of spesolimab in PPP; further evaluation is needed to better define those patients who might benefit from the treatment. A trial of spesolimab in NS is ongoing, while other spesolimab trials suggest that IL‐36 may only play a secondary role in the pathogenesis of atopic dermatitis. In conclusion, research into spesolimab has provided much needed insight into the role of IL‐36 in the human immune system and the mechanism behind IL‐36‐mediated inflammatory diseases. Spesolimab provides an efficacious targeted treatment for GPP, a disease with a high unmet medical need.