P048 Identification of IL36RN missense mutations in Crohn’s disease patients as a potentially new drug target for treating rare patients with over-activation of the IL36 signaling cascade

Abstract

Abstract Background The interleukin 36 (IL-36) family includes the agonists IL-36α, IL-36β, IL-36γ, which activate the NF-κB pathway and the natural antagonist IL-36RA, which inhibits IL-36 signaling. While missense mutations in the gene encoding IL-36RA (IL36RN) are associated with severe skin inflammation, their role in Crohn’s disease (CD) is currently unknown. Therefore, we here investigated if IL36RN mutations contribute to inflammation in CD and whether IL-36 signaling might represent a potential drug target for personalized therapy. Methods Mutations in IL36RN were identified by whole exome sequencing (WES) followed by targeted Sanger sequencing. Peripheral blood mononuclear cells (PBMCs) of affected patients were analyzed by mass cytometry and serum cytokines were measured by ELISA. Identified IL36RN mutations were characterized by overexpression experiments and functional assays. Clinical and molecular responses of one IL-36RN mutant patient to combined treatment with spesolimab and certolizumab pegol was assessed by fecal calprotectin, endoscopy, RNA sequencing and mass cytometry at week 0 and 12 of treatment. Results In a cohort of 47 ulcerative colitis patients, 177 CD patients and 34 healthy controls, we identified 3 CD patients with heterozygous missense mutations in IL36RN (IL-36RA S113L, IL-36RA P76L and IL-36RA L133I). In the patient carrying the IL-36RA S113L variant, we detected elevated serum levels of IL-18 and IL-23, as well as an increased frequency of TH17 cells in PBMCs, suggesting an overactivation of the IL-36 pathway. Overexpression experiments showed that IL-36RA S113L causes decreased expression of IL-36RA, resulting in increased IL-36 signaling. The patient was therefore treated with 1200 mg of the IL-36R blocking antibody spesolimab every 4 weeks and 200 mg of certolizumab pegol biweekly on the basis of an Out Of Scope request. This approach resulted in reduced intestinal inflammation and a reduction in the frequency of pro-inflammatory myeloid cells in PBMCs. Conclusion In this study, we show that pathogenic IL36RN mutations are present in a subset of CD patients and that blocking IL-36 signaling may represent a personalized therapeutic approach for this rare subset of patients in whom conventional biologic therapies have failed. Disclaimer Boehringer Ingelheim was given the opportunity to review the abstract for medical and scientific accuracy as well as intellectual property considerations in relation to the potential mention of BI substances. Boehringer Ingelheim had no role in the design, analysis or interpretation of the results in this study. Spesolimab was made available on the basis of an out of scope request. Boehringer Ingelheim was given the opportunity to review this abstract as a courtesy.