New-Onset, Treatment-Resistant Inflammatory Bowel Disease after Administration of Secukinumab for Plaque Psoriasis: A Case Report and Review of the Existing Literature

Introduction: Aberrant activation of the IL-23/IL-17 axis leads to inflammatory phenotypes with overlapping clinical characteristics.Inhibition of IL-17 has mostly an anti-inflammatory effect, but sporadic cases of new-onset IBD have been reported.Case description: We present the case of a 65-year-old male patient with new-onset Crohn's-like disease after treatment with secukinumab for skin psoriasis.Discontinuation of the IL-17 inhibitor and high-dose corticosteroid treatment were efficient initially, but a relapse was noted during corticosteroid tapering.Administration of certolizumab pegol did partially relieve the patient, but disease remission was only achieved with subcutaneous risankizumab therapy.Discussion: Clinical trials and real-world data indicate sporadic cases of new-onset IBD in patients receiving IL-17 inhibitors.Interestingly, our case is a "treatment-resistant" one since treatment with a biologic disease-modifying drug (bDMARD) usually leads to disease remission.As such, it is crucial to investigate the special characteristics of this clinical entity.