Intravenous ustekinumab maintenance treatment in patients with loss of response to subcutaneous dosing.

Background: Ustekinumab (UST) is indicated for the treatment of Crohn's disease (CD) and Ulcerative Colitis (UC). Despite having shown clinical effectiveness in the real world, some patients may lose response over time or need a higher dose to achieve it. In this context, UST intravenous (IV) maintenance has been proposed. Objectives: The primary endpoint of our study was to evaluate the efficacy and safety of maintenance IV UST treatment in Inflammatory Bowel Disease (IBD) patients who present with partial response or loss of response to subcutaneous (SC) UST. Design: We performed a monocentric observational retrospective study including patients with active IBD on maintenance treatment with IV UST. Methods: The clinical response and remission was analyzed at week 12, defined as either Harvey-Bradshaw Index ⩽ 4 for CD or partial Mayo Score ⩽ 2 for UC. The reduction of objective markers of disease activity, fecal calprotectin, and C-reactive protein was evaluated. Moreover, UST trough levels were measured pre- and post-UST IV maintenance and any adverse events were assessed. Results: We included 23 patients. Clinical remission at week 12 was achieved by 43.5% of the patients. The proportion of patients in clinical response after 12 weeks on UST IV maintenance was 82.6%. After a median follow-up of 9.3 months all patients remained on IV UST maintenance. No adverse events were recorded in any patient for the duration of the study. Conclusions: IV UST maintenance treatment was able to recapture response in most of the patients who had lost response to SC maintenance.