Long-Term Safety and Efficacy of Risankizumab Treatment in Patients with Crohn's Disease: Results from the Phase 2 Open-Label Extension Study.

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 Results Sixty-five patients were enrolled, including 4 patients 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 8 patients (12.3%); none were neutralising. 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.