J&J's guselkumab shows 94% clinical remission at three years in Crohn's

Johnson & Johnson has presented two sets of late-stage clinical data for its IL-23 inhibitor guselkumab (TREMFYA) at the United European Gastroenterology Week (UEG Week) conference, reinforcing the drug's long-term efficacy profile in Crohn's disease and extending its evidence into perianal fistula, a complication that has historically been difficult to treat.

The headline figures come from a Week 144 analysis of the Phase 3 GALAXI 2 and 3 studies, which enrolled adults with moderately to severely active Crohn's disease. Among patients receiving guselkumab 100 mg every eight weeks, 94% achieved clinical remission at the three-year mark, as defined by a Crohn's Disease Activity Index score below 150. In the same dose group, 52% achieved endoscopic remission as assessed by the Simple Endoscopic Score for Crohn's Disease. Corticosteroid-free clinical remission was reported in 89% of patients in the lower-dose arm. Rates in the 200 mg every four-weeks cohort were broadly comparable, with 91% achieving clinical remission and 61% endoscopic remission.

J&J reported that 74% of the 582 guselkumab-treated patients remained on treatment through the full three years, and that the safety profile was consistent with prior observations. Common adverse events included respiratory tract infections, diarrhoea, and injection site reactions.

As-observed caveats

The GALAXI long-term extension results are as-observed analyses, meaning they capture only those patients still on treatment with data available at Week 144. Patients who discontinued, underwent dose adjustment, or lacked follow-up data were excluded. That methodology, standard in long-term extension studies, tends to favour responders and means the headline remission rates should not be read as outcomes across the full randomised population. The clinical picture for patients who dropped out before Year 3 is not captured in the figures presented at UEG Week.

Speaking at the conference, Professor Silvio Danese of Vita-Salute San Raffaele University in Milan said: "The three-year GALAXI results provide valuable longer-term evidence, showing that high levels of clinical remission were accompanied by sustained endoscopic and corticosteroid-free outcomes across both guselkumab maintenance regimens." Danese is a paid consultant for Johnson & Johnson.

Fistula data and competitive positioning

The second dataset, from the Phase 3 FUZION study, addresses perianal fistula, a complication affecting a subset of Crohn's patients that carries significant morbidity. The 48-week analysis showed combined fistula remission, measured by both clinical assessment and blinded central MRI review, increased from 28% at Week 24 to 35% at Week 48 in the 100 mg every eight-weeks maintenance group. In the higher-dose 200 mg every four-weeks arm, rates were stable at around 26 to 27% across the same period. Overall, 90% of randomised patients completed treatment through Week 48.

J&J is positioning guselkumab as the only IL-23 inhibitor to have demonstrated efficacy in a dedicated, randomised, placebo-controlled trial specifically in patients with Crohn's disease and perianal fistula. That framing is noteworthy in a competitive IL-23 class that includes risankizumab (AbbVie's Skyrizi) and mirikizumab (Eli Lilly's Omvoh), both of which are approved in Crohn's disease. Neither has reported results from a dedicated perianal fistula trial, though the comparative clinical significance of the FUZION endpoint definition, which demands complete fistula closure confirmed by MRI, will be scrutinised by gastroenterologists and payers alike.

Inflammatory bowel disease affects an estimated two million people across Europe, and advanced therapy penetration in Crohn's disease continues to grow as treat-to-target strategies, incorporating endoscopic as well as symptom endpoints, become standard of care. GALAXI is designed to run for a total of five years, meaning further long-term extension data will be forthcoming. Investors and clinicians will be watching for the full five-year dataset, as well as any head-to-head comparative data in the fistula indication.