Efficacy and safety of mirikizumab in patients with moderately-to-severely active Crohn's disease: a phase 3, multicentre, randomised, double-blind, placebo-controlled and active-controlled, treat-through study

Background: Mirikizumab, a humanised monoclonal antibody that inhibits IL-23p19, is effective in moderate-to-severe ulcerative colitis. We aimed to evaluate the efficacy and safety of mirikizumab in patients with moderately-to-severely active Crohn's disease. Methods: VIVID-1 was a global phase 3, randomised, double-blind, double-dummy, placebo-controlled and active-controlled, treat-through study. The study enrolled adult patients at 324 sites (hospitals or medical centres, clinical practices, and clinical research sites) in 33 countries across Europe, Asia, North America, Central America, South America, and Australia. Adult patients with moderately-to-severely active Crohn's disease and previous inadequate response, loss of response, or intolerance to one or more approved biological therapies or conventional therapies were randomly assigned 6:3:2 to receive mirikizumab 900 mg intravenously at weeks 0, 4, and 8, then 300 mg subcutaneously every 4 weeks from weeks 12 to 52; ustekinumab about 6 mg/kg intravenously at week 0, then 90 mg subcutaneously every 8 weeks from weeks 8 to 52; or placebo. The coprimary endpoints assessing superiority of mirikizumab over placebo were composite endpoints: patient-reported outcome (PRO) clinical response at week 12 and endoscopic response at week 52 (endoscopic response-composite), and PRO clinical response at week 12 and Crohn's Disease Activity Index (CDAI) clinical remission at week 52 (CDAI clinical remission-composite). The adjusted risk differences were calculated, and the comparison was performed by the Cochran–Mantel–Haenszel test. Non-responder imputation was used. VIVID-1 was registered on ClinicalTrials.gov, NCT03926130, and is now complete. Findings: Between July 23, 2019, and Aug 23, 2023, 1150 patients were randomly assigned and received study treatment (safety population); 1065 patients were included in the efficacy population and received mirikizumab (n=579), ustekinumab (n=287), or placebo (n=199). Both coprimary endpoints were met: endoscopic response-composite was reached in 220 (38·0%) of 579 patients on mirikizumab versus 18 (9·0%) of 199 on placebo (99·5% CI 20·6–36·8; p<0·0001); CDAI clinical remission-composite was reached in 263 (45·4%) of 579 patients on mirikizumab versus 39 (19·6%) of 199 patients on placebo (99·5% CI 15·9–35·6; p<0·0001). The incidence rates of overall adverse events and discontinuations in patients treated with mirikizumab were lower compared with placebo. The most common adverse event across the three groups was COVID-19. Serious adverse events were reported in 65 (10·3%) of 630 patients on mirikizumab, 33 (10·7%) of 309 patients on ustekinumab, and 36 (17·1%) of 211 patients on placebo. There were three deaths during VIVID-1, one in the ustekinumab group, and two in the placebo group, including one in a placebo non-responder who switched to mirikizumab after week 12. None of the deaths were considered related to the study drug. The safety of mirikizumab in Crohn's disease was consistent with its known favourable profile. Interpretation: Mirikizumab was safe and effective as induction and maintenance treatment for patients with moderately-to-severely active Crohn's disease who had intolerance, inadequate response, or loss of response to standard therapy. Funding: Eli Lilly and Company.