Guselkumab in patients with moderately to severely active ulcerative colitis (QUASAR): phase 3 double-blind, randomised, placebo-controlled induction and maintenance studies

Interleukin-23 inhibition is effective in treating ulcerative colitis. Guselkumab is a dual-acting, human IgG1, interleukin-23p19 subunit inhibitor that potently neutralises interleukin-23 and can bind to CD64. We aimed to evaluate the efficacy and safety of guselkumab as induction and maintenance therapy in patients with ulcerative colitis. The primary populations of these two phase 3, randomised, double-blind, placebo-controlled studies (QUASAR phase 3 induction and maintenance) included randomised and treated adults with moderately to severely active ulcerative colitis (induction baseline modified Mayo score from 5 to 9) with inadequate response or intolerance to conventional or advanced ulcerative colitis therapy. Patients were randomly assigned (3:2) to receive guselkumab 200 mg given intravenously or placebo at weeks 0, 4, and 8 (phase 3 induction study). All patients were randomly assigned using web-based interactive response technology. Patients in clinical response 12 weeks after guselkumab induction given intravenously (from QUASAR phase 2b and phase 3 induction studies) were randomly assigned (1:1:1) at maintenance week 0 to guselkumab 200 mg given subcutaneously every 4 weeks or 100 mg every 8 weeks or placebo for 44 weeks (maintenance). Primary endpoints were clinical remission at induction week 12 and maintenance week 44. This study is registered with ClinicalTrials.gov, NCT04033445. The induction study primary population included 701 patients (guselkumab 200 mg given intravenously 60% [421 patients]; placebo 40% [280 patients]). The maintenance study primary population included 568 guselkumab induction responders randomly assigned to receive guselkumab 200 mg given subcutaneously every 4 weeks (190 [33%] patients) or 100 mg every 8 weeks (188 [33%] patients) or placebo (guselkumab withdrawal 190 [33%] patients). A significantly greater proportion of patients treated with guselkumab given intravenously had clinical remission at induction week 12 (23% [95 of 421 patients]) than did placebo-treated patients (8% [22 of 280 patients]; adjusted treatment difference 15%, 95% CI 10–20; p