Psoriasis and inflammatory bowel disease: concomitant IMID or paradoxical therapeutic effect? A scoping review on anti-IL-12/23 and anti-IL-23 antibodies.

Inflammatory bowel diseases (IBD) and psoriasis are chronic inflammatory conditions belonging to the heterogeneous group of immune-mediated inflammatory diseases (IMIDs). A significant bidirectional link between these two entities has been observed, conditioning an increased risk of IBD in patients with psoriasis and vice-versa. Biological therapies used for IBD may lead to the occurrence of psoriasis as a "paradoxical reaction." The objective of this study is to analyze the current evidence on the association between psoriasis and IBD, particularly finding case reports of the appearance or aggravation of psoriasis under therapy with interleukin-12/23 (IL-12/23) and IL-23 inhibitors. We conducted comprehensive research to identify studies examining the association between psoriasis and IBD and to find case presentations that reported the appearance or aggravation of psoriasis under biologic therapy with IL-12/23 and IL-23 inhibitors up to March 2024. Clinical trials for IL-12/23 and IL-23 inhibitors in IBD were analyzed to find cases of paradoxical psoriasis as registered adverse events. The sources of evidence are PubMed and ClinicalTrials.gov. For each included case report, data on patient characteristics concerning their age, sex, and comorbidities were selected. Moreover, information regarding the indication for biologic therapy, time to onset of paradoxical psoriasis after starting treatment, clinical presentation, and management of the paradoxical psoriasis was extracted. We found 10 reported cases of ustekinumab-induced new-onset or worsening psoriasis and one reported case of paradoxical psoriasis induced by risankizumab in the literature. Four cases of paradoxical psoriasis have been also registered in clinical trials involving ustekinumab treatment in IBD. Psoriasis can constitute a rare paradoxical adverse event of ustekinumab treatment, but further studies are needed to better clarify the cytokine imbalance that leads to this phenomenon induced by inhibition of IL-12/23 and IL-23. Still, few real-world data exist to draw any conclusions, but risankizumab may positively treat psoriasis induced by ustekinumab.