Phase 3 FUZION Data Show Guselkumab Benefit in Perianal Fistulizing Crohn Disease

Guselkumab achieved significantly higher rates of combined fistula remission than placebo at 24 weeks in adults with active perianal fistulizing Crohn disease, according to late-breaking Phase 3 data from the FUZION study presented at Digestive Disease Week 2026.¹ The finding is notable because randomized controlled data in this specific Crohn complication have been limited for years, despite the substantial morbidity associated with persistent drainage, abscesses, pain, and repeat surgical procedures.^2,3

“The pain, swelling and persistent drainage associated with perianal fistulizing Crohn's disease can be profoundly disruptive to patients' daily lives,” study investigator Laurent Peyrin-Biroulet, MD, PhD, said in the company statement.¹ He added that durable fistula closure without repeated surgery remains an important unmet need.

How was the FUZION trial designed?

In the company’s report, FUZION was described as a randomized, placebo-controlled, double-blind, multicenter Phase 3 study enrolling adults with 1 or more active draining perianal fistulas confirmed by blinded central magnetic resonance imaging review and Crohn Disease Activity Index scores below 350.^1,4 Eligible patients had experienced inadequate response to corticosteroids, immunomodulators, or as many as two advanced therapy classes.^1,4 Patients were randomized 2:2:1 to intravenous guselkumab induction at weeks zero, four, and eight followed by either 100 mg subcutaneously every eight weeks or 200 mg subcutaneously every four weeks, or to placebo.^1,4

What were the key efficacy results at 24 weeks?

The primary endpoint—combined fistula remission at week 24—was defined as complete closure of external openings, no drainage, no new fistulas, and no fluid collections on MRI.¹

Remission rates were:

• 28.3% (100 mg every eight weeks)
• 27.0% (200 mg every four weeks)
• 10.3% (placebo)

Both treatment arms showed statistically significant improvements versus placebo.¹

What do we know about safety so far?

According to Johnson & Johnson, adverse events through 24 weeks were consistent with the known safety profile of guselkumab in Crohn disease.¹ In approved inflammatory bowel disease labeling, important risks include serious hypersensitivity reactions, infections including tuberculosis, and liver test abnormalities; commonly reported adverse reactions include upper respiratory tract infection, headache, injection-site reactions, arthralgia, diarrhea, gastroenteritis, abdominal pain, and bronchitis.⁴ The press release did not provide numerical safety event rates for FUZION, limiting direct assessment of risk-benefit balance in this population.

Why is perianal fistulizing disease so challenging to treat?

Perianal fistulizing disease affects nearly one-quarter of patients with Crohn disease and significantly impacts quality of life.¹˒²˒³ Management typically combines surgery and medical therapy, yet durable remission remains difficult.²

What questions remain unanswered?

Despite promising results, key gaps include:

• Lack of long-term durability data
• Limited subgroup and secondary endpoint reporting
• No detailed safety tables
• Unclear correlation between MRI healing and clinical outcomes

How might this impact future treatment strategies?

Guselkumab, a monoclonal antibody, targets the IL-23 pathway and is already approved for multiple inflammatory conditions.⁴ If confirmed in peer-reviewed data, these findings could influence treatment algorithms, especially for patients who fail prior therapies.

References

1. Peyrin-Biroulet L, et al. Guselkumab for perianal fistulizing Crohn's disease: week 24 results from the phase 3, randomized, double-blind, placebo-controlled, multicenter FUZION study. Abstract 1058b. Presented at: Digestive Disease Week; May 2-5, 2026. Accessed May 5, 2026. https://www.prnewswire.com/news-releases/johnson--johnson-study-shows-tremfya-guselkumab-is-the-first-and-only-il-23-inhibitor-to-demonstrate-efficacy-in-perianal-fistulizing-crohns-disease-302760610.html
2. Sulak A, et al. (2023 Oct 6). Where are we and where to next?-the future of perianal Crohn's disease management. J Clin Med. doi:10.3390/jcm12196379
3. Spinelli A, Yanai H, Girardi P, et al. (2023 Jul 25).The impact of Crohn's perianal fistula on quality of life: results of an international patient survey. Crohns Colitis 360. doi:10.1093/crocol/otad036
4. ClinicalTrials.gov. A study of guselkumab in participants with fistulizing, perianal Crohn's disease (FUZION CD). NCT05347095. Accessed March 2026. https://clinicaltrials.gov/study/NCT05347095?tab=researcher