TREMFYA – Use in Adult Patients with Fistulizing Crohn's Disease

SUMMARY  

• The company cannot recommend any practices, procedures, or usage that deviate from the approved labeling.
• A phase 3 randomized clinical trial is ongoing to evaluate the efficacy and safety of TREMFYA in fistulizing, perianal Crohn’s disease (CD). Results up to week 24 are reported below. Additional details are available at clinicaltrials.gov: NCT05347095.^1,2 

clinical data

FUZION Study

Study Design/Methods

• Participants enrolled in this study met the following criteria:²
  • Adults with ≥1 active draining perianal fistula confirmed by blinded central magnetic resonance imaging (MRI) review
  • Crohn’s Disease Activity Index (CDAI) <350
  • Inadequate response to oral corticosteroids, azathioprine, 6-mercaptopurine, methotrexate, or up to 2 advanced-therapy classes
• Patients were randomized (2:2:1) to receive:  
  • TREMFYA 200 mg intravenous (IV) induction at weeks 0, 4 and 8 followed by maintenance therapy of TREMFYA 100 mg subcutaneous (SC) every 8 weeks (q8w) or 200 mg SC every 4 weeks (q4w)
  • PBO
• The primary outcome was the combined fistula remission at week 24.
  • Combined fistula remission was defined as: 1) closure of all treated external openings without development of new fistulas or abscesses and without any drainage by the external openings (occurring spontaneously or after gentle finger compression) and 2) absence of collections >2 cm of the perianal fistulas in at least two of three dimensions, confirmed by a blinded central review of the MRI results.

Results

• Among 286 patients in the full analysis set, 113 received TREMFYA 100 mg SC q8w, 115 received TREMFYA 200 mg SC q4w and 58 received PBO; 91.3% completed 24 weeks of therapy.² 
• The mean age was 36.5 years and the mean Crohn’s Disease Activity Index (CDAI) score was 148.7; 58% had 1 open or draining fistula and 42% had multiple draining fistulas.
• At week 24, significantly greater proportions of patient treated with TREMFYA achieved combined fistula remission vs those treated with PBO (28.3% for TREMFYA 100 mg SC q8w, 27% for TREMFYA 200 mg SC q4w, and 10.3% for PBO)
  • The treatment difference of TREMFYA 100 mg SC q8w vs PBO was 18.0% (95% Cl; 7.0-29.0; P=0.007)
  • The treatment difference of TREMFYA 200 mg SC q4w vs PBO was 16.6% (95% Cl: 5.6-27.6; P=0.013)
• No new safety signals were identified. For adverse events, see Table: Summary of Adverse Events Through Week 24.

Case Report

Croitoru et al (2022)¹ described the case of a 43-year-old male patient with a history of fistulizing CD and who was referred for suspected Hidradenitis Suppurativa (HS).

• The patient was diagnosed with CD due to a 5-year presentation of weight loss and diarrhea, confirmed by endoscopic assessment. His CD progressed to pancolitis involving the rectum with multiple draining fistulas.
• After failing multiple treatments, including antibiotics, mesalamine, azathioprine, and various tumor necrosis factor (TNF) inhibitors, he underwent surgical intervention initially with loop ileostomy, but his perianal disease continued to persist.
• Over the next year, the patient was treated with ustekinumab but developed pancolitis. This led to initiation of methylprednisolone treatment, bridged to a modified total proctocolectomy with end ileostomy. Perianal dissection was foregone, and a small stump was left in place.
• Over the following months, the patient was put on steroid taper and later treated with a TNF inhibitor. Addition of sulfasalazine, methotrexate, hyperbaric oxygen, and concurrent intralesional steroids minimally benefited.
• The arrangement of draining tract and inflammation nodules led to suspicion for concomitant HS and the patient was referred to dermatology clinical for evaluation and management.
  • Upon further examinations, there were deep ulcerated fissures in the bilateral groin with linear sinuses with peripheral erosions and fibrinoid changes at the wound. There were also many tender and deep nodules and subcutaneous abscesses adjacent ulcers, which extended perianally. The patient described ongoing weight loss, without fever, and abdominal pain and minimal change in stoma output.
  • Given the patient's history of fistulizing CD and extensive wounds, it was suspected that he had ongoing occult inflammation intestinal disease and fistulation to skin. MRI of the pelvis showed an intramural abscess in the most superior aspect of the rectal stump and multiple emanating fistulas.
  • Treatment with ertapenem drastically reduced perianal pain and discharge and the patient was subsequently started on TREMFYA 100 mg every 8 weeks.
  • Within 6 months of initiating TREMFYA, the patient experienced near complete resolution of all inflammatory nodules and abscesses with significant weight gain and improvement of the bilateral perineal ulcerative to near resolution. His serum C-reactive protein levels decreased from baseline (60 to 8.3).
  • Repeated MRI of the pelvis and abdomen showed interval resolution and improvement of multiple intestinal fistulas with reduction in size of intramural abscess. The patient underwent multidisciplinary re-evaluation for surgical candidacy to remove the remaining portion of his rectal stump.

Literature Search

A literature search of MEDLINE^®, EMBASE^®, BIOSIS Previews^®, DERWENT^® (and/or other resources, including internal/external databases) was conducted on 13 April 2026.