Abstract
BACKGROUND AND AIMS: Risankizumab, an interleukin-23 antibody, demonstrated efficacy and acceptable safety in a phase 2 study of patients with moderate-to-severe refractory Crohn's disease. This open-label extension investigated the long-term safety, pharmacokinetics, immunogenicity and efficacy of risankizumab in responders to risankizumab in the parent phase 2 study. METHODS: Enrolled patients had achieved clinical response [decrease in Crohn's Disease Activity Index from baseline ≥100] without clinical remission [Crohn's Disease Activity Index <150] at Week 26, or clinical response and/or remission at Week 52 in the parent phase 2 study and received open-label subcutaneous risankizumab 180 mg every 8 weeks. RESULTS: Sixty-five patients were enrolled, including four who had lost response in the parent study and were first reinduced with risankizumab 600 mg every 4 weeks [three infusions]. Patients received risankizumab for a median of 33 months [total: 167.0 patient-years]. The rate of serious adverse events was 24.6 events/100 patient-years; the majority were gastrointestinal in nature. Rates of serious infections, opportunistic infections and fungal infections were 4.2, 1.8, and 6.6 events/100 patient-years, respectively. No deaths, malignancies, adjudicated major adverse cardiovascular events, latent/active tuberculosis or herpes zoster were reported. Treatment-emergent anti-drug antibodies developed in eight patients [12.3%]; none were neutralizing. Efficacy outcomes were maintained during the study, including the proportions of patients [observed analysis] with clinical remission [>71%] and endoscopic remission [>42%]. CONCLUSIONS: Long-term maintenance treatment with subcutaneous risankizumab 180 mg every 8 weeks was well tolerated by patients with Crohn's disease, with no new safety signals. Clinical trial registration number: NCT02513459.