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CompletedNCT03760003Updated Nov 28, 2025Results posted

Dose-Ranging Phase 2b Study of ABX464 in Moderate to Severe Ulcerative Colitis

A Phase 2 interventional study of ABX464 100 mg and ABX464 50 mg in Ulcerative Colitis, sponsored by Abivax S.A.. Completed at 130 sites in 17 countries. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2025-11-28.

Sponsored by Abivax S.A. · Phase 2, Interventional, and Treatment

Phase
Phase 2
Study type
Interventional
Enrollment
355
Allocation
Randomized
Ages
18 Years to 75 Years
Sex
All
01

Study summary

Phase 2b study to evaluate the efficacy and the safety of 3 dose-levels of ABX464, administered daily in patients with moderate to severe Ulcerative Colitis.

Read the detailed description

This phase 2b study will evaluate the efficacy and the safety of 3 dose-levels of ABX464, administered daily in improving Modified Mayo Score (MMS) in patients with moderate to severe Ulcerative Colitis who have inadequate response, loss of response, or intolerance with at least one of the following agents: immunosuppressant treatment (i.e. azathioprine, 6-mercaptopurine, methotrexate), tumor necrosis factor alpha [TNF-α] inhibitors, vedolizumab, JAK inhibitors and/or corticosteroid treatment .

Eligible patients will be randomized into 4 parallel intervention/treatment groups: 100mg q.d of ABX464, 50mg q.d of ABX464, 25mg q.d of ABX464, or matching placebo and will be treated for 16 weeks.

02

Conditions studied

  • Ulcerative Colitis

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Keywords

  • ABX464
  • Refractory patients
  • Phase 2b
  • Dose Ranging
03

In context

Colitis, Ulcerative

1,492 studies on the registry are indexed under Colitis, Ulcerative; 399 are open to participants now.

This study's enrollment of 355 is above the median of 71 across 1,042 interventional studies indexed under Colitis, Ulcerative.

Browse Colitis, Ulcerative studies →

Lead sponsor

Abivax S.A. is the lead sponsor of 22 studies on the registry; 2 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 75 Years
Sexes eligible
All
Accepts healthy volunteers
No

Inclusion criteria

  • Men or women age 18 - 75 years;
  • Diagnosis of moderate to severe active UC (including ulcerative proctitis if proximal extension of disease occurs beyond 10 cm) confirmed by endoscopy and histology at least 12 Weeks prior to screening visit. Moderate to severe active UC defined by Modified Mayo Score (MMS) of 5 to 9 inclusive (on a scale of 0-9). Moderate to severe active UC should be confirmed at screening visit with a centrally read endoscopy sub-score of at least 2 (on a scale of 0-3);

  • Patients having either a documented inadequate response, no response, a loss of response, or an intolerance (defined as the occurrence of at least one Adverse Reaction leading to treatment discontinuation) to either immunosuppressant treatment (i.e., azathioprine, 6-mercaptopurine, methotrexate), tumor necrosis factor [TNF] inhibitors, vedolizumab, JAK inhibitors and/or corticosteroid treatment. Inadequate response, no response, loss of response is defined as:

    i. Active disease or relapse in spite of thiopurines or methotrexate given at an appropriate dose for at least 3 months (i.e. azathioprine 2-2.5 mg/kg/day or mercaptopurine 1-1.5 mg/kg/day in the absence of leukopenia), and/or ii. Active disease despite corticosteroids treatment (prednisolone up to 0.75 mg/kg/day) over a period of 4 Weeks, and/or iii. Active disease or relapse in spite of adequate treatment (as defined in the SmPC) with tumor necrosis factor [TNF] inhibitors or vedolizumab, and/or iv. Active disease or relapse in spite of adequate treatment with JAK inhibitors over a period of at least 6 Weeks.

  • Patients receiving oral corticosteroids must have been on a stable dose of prednisone or prednisone equivalent (≤20 mg/day) or on beclomethasone diproprionate (≤5mg/day) or on budesonide MMX (≤9 mg/day) for at least 2 Weeks prior to the screening visit;
  • Topical corticosteroids and topical 5-aminosalicylic acid preparations must have been withdrawn at least 2 Weeks prior to the screening visit;
  • Patients who are on oral 5-aminosalicylic acid must have been on a stable dose for at least 4 Weeks prior to the screening visit;
  • Patients who are receiving immunosuppressants in the form of azathioprine, 6-mercaptopurine, or methotrexate needed to be on a stable dose for at least 4 Weeks prior to screening visit. Patients taking methotrexate also are advised to take folic acid 1 mg/day (or equivalent) supplementation if there is no contraindication;
  • Patients on probiotics (e.g., Culturelle® [Lactobacillus GG, i-Health, Inc.], Saccharomyces boulardii) must be on stable doses for at least 2 Weeks prior to the screening visit;
  • Patients on antidiarrheals (e.g., loperamide, diphenoxylate with atropine) must be on stable doses for at least 2 Weeks prior to the screening visit;
  • Patients who have received tumor necrosis factor [TNF] inhibitors, vedolizumab or other biologics must have discontinued therapy at least 8 Weeks prior to the screening visit due to lack or insufficient efficacy or intolerance;
  • Patients previously treated with cyclosporine, tacrolimus or JAK inhibitors must have discontinued therapy at least 4 Weeks prior to the screening visit due to lack or insufficient efficacy or intolerance;
  • Patients previously treated with tube feeding, defined formula diets, or parenteral alimentation/nutrition must have discontinued treatment 3 Weeks before the screening visit and must be able to take, orally, appropriate amount of food (calories) and liquids to maintain body weight;
  • Patients with surveillance colonoscopy defined as per ECCO guidelines;

  • Patients with the following hematological and biochemical laboratory parameters obtained at screening:

    i. Hemoglobin > 9.0 g dL-1; ii. Absolute neutrophil count ≥ 750 mm-3; iii. Platelets ≥ 100,000 mm-3; iv. Total serum creatinine ≤ 1.3 x ULN (upper limit of normal); v. Creatinine clearance > 90 mL min-1 by the Cockcroft-Gault equation within 60 days prior to baseline; vi. Total serum bilirubin \< 1.5 x ULN; vii. Alkaline phosphatase, AST (SGOT) and ALT (SGPT) \< 2 x ULN;

  • Patients are able and willing to comply with study visits and procedures as per protocol;
  • Patients should understand, sign and date the written voluntary informed consent form at the screening visit prior to any protocol-specific procedures are performed;
  • Patients should be affiliated to a social security regimen (for French sites only);
  • Females and males receiving the study treatment (potentially in combination with immunosuppressant) and their partners must agree to use a highly effective contraceptive method during the study and for 6 months after end of study or early termination. Contraception should be in place at least 2 Weeks prior to study participation. Women must be surgically sterile or if of childbearing potential must use a highly effective contraceptive method. Women of childbearing potential (WOCBP) will enter the study after confirmed menstrual period and a negative pregnancy test. Highly effective methods of contraception include true abstinence, intrauterine device (IUD) or hormonal contraception aiming at inhibition of ovulation, intrauterine hormone releasing system, bilateral tubal ligation, vasectomized partner. True abstinence is defined when this is in line with the preferred and usual lifestyle of the patient. In each case of delayed menstrual period (over one month between menstruations) confirmation of absence of pregnancy is required. This recommendation also applies to WOCBP with an infrequent or irregular menstrual cycle. Female and male patients must not be planning pregnancy during the trial and for 6 months post completion of their participation in the trial. In addition, male participants should use condoms and not donate sperm as long as contraception is required.

Exclusion criteria

Exclusion Criteria:

  • Patients with Crohn's Disease (CD) or presence or history of fistula, indeterminate colitis (IC), infectious/ischemic colitis or microscopic colitis (lymphocytic and collagenous colitis);
  • History of toxic megacolon, abdominal abscess, symptomatic colonic stricture or stoma; history or imminent colectomy, colonic malignancy;
  • History or current evidence of colonic dysplasia or adenomatous colonic polyps. Patient with severe gastrointestinal complications; e.g., short bowel syndromes, recent or planned bowel surgery, Ileostomy and/or colostomy, recent bowel perforation;
  • History of more than one episode of herpes zoster or a history (single episode) of disseminated zoster;
  • Patients with active infections at screening such as infected abdominal abscess, Clostridium difficile (stool antigen and toxin required), CMV (positive IgM), TB and recent infectious hospitalization;
  • Patients previously treated with ABX464;
  • Acute, chronic or history of clinically relevant pulmonary, cardiovascular, hepatic, pancreatic or renal functional abnormality, encephalopathy, neuropathy or unstable CNS pathology such as seizure disorder, angina or cardiac arrhythmias, active malignancy or any other clinically significant medical problems as determined by physical examination and/or laboratory screening tests and/or medical history;
  • Acute, chronic or history of immunodeficiency or autoimmune disease;
  • History of malignancy excluding patients considered cured (5 years disease free survivors);
  • Serious illness requiring systemic treatment and/or hospitalization within 3 Weeks prior to baseline;
  • Pregnant or breast-feeding women;
  • Illicit drug or alcohol abuse or dependence;
  • Patients who received live vaccine 30 days or fewer before first dose of study treatment and/or who's planning to receive such a vaccine during the study duration;
  • Use of any investigational or non-registered product within 3 months or within 5 half-lives preceding baseline, whichever is longer and during the study;
  • Any condition, which in the opinion of the investigator, could compromise the patient's safety or adherence to the study protocol.
05

Study design

Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Quadruple (Participant, Care provider, Investigator, Outcomes assessor)
Enrollment
355 participants (actual)

Study arms

  • Experimental
    ABX464 100 mg

    ABX464 100 mg was administered orally (capsules) once daily for 16 weeks

    Drug: ABX464 100 mg

  • Experimental
    ABX464 50 mg

    ABX464 50 mg was administered orally (capsules) once daily for 16 weeks

    Drug: ABX464 50 mg

  • Experimental
    ABX464 25 mg

    ABX464 25 mg was administered orally (capsules) once daily for 16 weeks

    Drug: ABX464 25 mg

  • Placebo comparator
    Matching Placebo

    Matching placebo was administered orally (capsules) once daily for 16 weeks

    Drug: Placebo

Interventions

  • DrugABX464 100 mg

    ABX464 100 mg (two capsules of ABX464 50 mg) once daily for 16 weeks

    Also known as: Obefazimod 100 mg

  • DrugABX464 50 mg

    ABX464 50 mg (one capsule of ABX464 50 mg + one capsule of placebo) once daily for 16 weeks

    Also known as: Obefazimod 50 mg

  • DrugABX464 25 mg

    ABX464 25 mg (one capsule of ABX464 25 mg + one capsule of placebo) once daily for 16 weeks

    Also known as: Obefazimod 25 mg

  • DrugPlacebo

    Two capsules of placebo once daily for 16 weeks

    Also known as: Obefazimod placebo control

06

What researchers measure

Primary outcomes

  1. Reduction From Baseline in Modified Mayo Score (MMS) at Week 8

    Reduction from baseline in Modified Mayo Score (MMS) MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease.

    Time frame: Week 8

Secondary outcomes

  1. Reduction From Baseline in MMS at Week 16

    Reduction from baseline in Modified Mayo Score (MMS) MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease.

    Time frame: Week 16

  2. Number of Participants in Clinical Remission Per MMS at Week 8

    Number of participants who achieved clinical remission per Modified Mayo Score at Week 8 MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease. Clinical remission is defined as SFS ≤ 1, RBS of 0, and endoscopic subscore ≤ 1 (modified to exclude friability)

    Time frame: Week 8

  3. Number of Participants in Clinical Remission Per MMS at Week 16

    Number of participants who achieved clinical remission per Modified Mayo Score at Week 16 MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease. Clinical remission is defined as SFS ≤ 1, RBS of 0, and endoscopic subscore ≤ 1 (modified to exclude friability)

    Time frame: Week 16

  4. Number of Participants With Clinical Response at Week 8

    Clinical response is defined as a reduction in MMS of at least 2 points and greater than or equal to 30 percent from baseline with an accompanying decrease in rectal bleeding sub-score of greater than or equal to 1 point or absolute rectal bleeding sub-score of less than or equal to 1 point.

    Time frame: Week 8

  5. Number of Participants With Clinical Response at Week 16

    Clinical response is defined as a reduction in MMS of at least 2 points and greater than or equal to 30 percent from baseline with an accompanying decrease in rectal bleeding sub-score of greater than or equal to 1 point or absolute rectal bleeding sub-score of less than or equal to 1 point.

    Time frame: Week 16

  6. Number of Participants With Endoscopic Improvement at Week 8

    Endoscopic improvement is defined as an endoscopic subscore of 0 or 1 (excluding friability) Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher endoscopic score indicates more severe disease.

    Time frame: Week 8

  7. Number of Participants With Endoscopic Improvement at Week 16

    Endoscopic improvement is defined as an endoscopic subscore of 0 or 1 (excluding friability) Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher endoscopic score indicates more severe disease.

    Time frame: Week 16

  8. Number of Participants With Mucosal Healing at Week 8

    Mucosal healing is defined as endoscopic remission (overall mucosal appearance at endoscopy subscore=0) and histological remission (Geboes score \<2.0 based on rectal biopsy). The endoscopic subscore ranges from 0 (normal or inactive disease) to 3 (severe disease with spontaneous bleeding, ulceration). The Geboes histologic index includes seven histological features (architectural change, chronic inflammatory infiltrate, lamina propria neutrophils and eosinophils, neutrophils in epithelium, crypt destruction and erosion or ulcers). The Geboes score has 6 grades, each with 3-5 subgrades: Grade 0, structural change only; Grade 1, chronic inflammation; Grade 2, lamina propria neutrophils and eosinophils; Grade 3, neutrophils in epithelium; Grade 4, crypt destruction; and Grade 5, erosions or ulceration. A higher score is associated with higher disease activity.

    Time frame: Week 8

  9. Number of Participants With Mucosal Healing at Week 16

    Mucosal healing is defined as endoscopic remission (overall mucosal appearance at endoscopy subscore=0) and histological remission (Geboes score \<2.0 based on rectal biopsy). The endoscopic subscore ranges from 0 (normal or inactive disease) to 3 (severe disease with spontaneous bleeding, ulceration). The Geboes histologic index includes seven histological features (architectural change, chronic inflammatory infiltrate, lamina propria neutrophils and eosinophils, neutrophils in epithelium, crypt destruction and erosion or ulcers). The Geboes score has 6 grades, each with 3-5 subgrades: Grade 0, structural change only; Grade 1, chronic inflammation; Grade 2, lamina propria neutrophils and eosinophils; Grade 3, neutrophils in epithelium; Grade 4, crypt destruction; and Grade 5, erosions or ulceration. A higher score is associated with higher disease activity.

    Time frame: Week 16

  10. Number of Participants With Reduction of Stool Frequency Relative to Baseline (Day 1)

    Participants recorded stool frequency using an electronic subject diary on a daily basis. The stool frequency subscore (SFS) ranges from 0 to 3 according to the following scale: Score 0: Normal number of stools Score 1: 1 to 2 stools per day more than normal Score 2: 3 to 4 stools per day more than normal Score 3: 5 or more stools per day more than normal Decreasing score indicates improvement.

    Time frame: Day 8, Day 29, Day 57, Day 85, Day 113, and Day 120 (End of Study)

  11. Number of Participants With Reduction of Rectal Bleeding Frequency Relative to Baseline

    Participants recorded rectal bleeding in an electronic subject diary on a daily basis. Rectal bleeding score (RBS) is taken as the worst subscore of the three most recent scores within 7 days prior to the visit. The rectal bleeding subscore ranges from 0 to 3 according to the following scale: Score 0: No blood seen Score 1: Streaks of blood with stool less than half the time Score 2: Obvious blood with stool most of the time Score 3: Blood alone passed A lower score represents an improvement in rectal bleeding.

    Time frame: Day 8, Day 29, Day 57, Day 85, Day 113, and Day 120 (End of Study)

  12. Partial Modified Mayo Score Change From Baseline

    Partial Modified Mayo Score (pMMS) Change from baseline The pMMS is a composite score of UC disease activity based on the following 2 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools per day) to 3 (5 or more stools per day more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). The overall pMMS score ranges from 0 to 6 with higher scores representing more severe disease.

    Time frame: Day 8, Day 29, Day 57, Day 85, Day 113, and Day 120 (End of Study)

  13. Number of Participants With Reduction Relative to Baseline in Fecal Calprotectin at Weeks 8 and 16

    Fecal Calprotectin (FC) is a non-invasive surrogate marker of inflammation in the small intestine and levels below 250 ug/g is associated with mucosal healing. FC levels were measured using enzyme-linked immunosorbent assay (ELISA) and/or a validated quantitative rapid test. Outcome will be measured based on a reduction in FC relative to baseline values.

    Time frame: Week 8 and Week 16

  14. Number of Participants With Reduction Relative to Baseline in C Reactive Protein at Weeks 8 and 16

    CRP is an acute-phase protein which provides an objective criterion of inflammatory activity. CRP has a short half-life (19 hours) and therefore rises early after the onset of inflammation and rapidly decreases after resolution of the inflammation. It is induced by interleukin-6, TNF-alpha and other pro-inflammatory cytokines that are produced within the intestinal lamina propria. Outcome will be measured based on a reduction in CRP relative to baseline values.

    Time frame: Week 8 and Week 16

  15. miRNA-124 Expression (Copy Number) in Whole Blood at Week 8 and Week 16

    Absolute quantification (QuantaSoft Pro) of the miR-124 copy number was performed at Week 8 and Week 16 using droplet digital PCR technology (ddPCR) on whole blood samples. "0" in the placebo column means "no signal", so BLQ (Below the level of quantification).

    Time frame: Week 8 and Week 16

  16. IL-6 Serum Concentrations

    Serum samples from participants who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL6 was measured using the 8-plex assay on the ELLA Platform (Biotechne). All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-6 values - Day 1 IL-6 values/Day 1 IL-6 values)\*100

    Time frame: Day 1

  17. Number of Participants With Endoscopic Remission at Week 8

    Endoscopic remission is defined as an endoscopic subscore of 0. Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher score represents more severe disease.

    Time frame: Week 8

  18. Number of Participants With Endoscopic Remission at Week 16

    Endoscopic remission is defined as an endoscopic subscore of 0. Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher score represents more severe disease.

    Time frame: Week 16

  19. IL-10 Serum Concentrations

    Serum samples from patients who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL10 was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-10 values - Day 1 IL-10 values/Day 1 IL-10 values)\*100

    Time frame: Day 1

  20. IL-1B Serum Concentrations

    Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113). IL1beta was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-1B values - Day 1 IL-1B values/Day 1 IL-1B values)\*100

    Time frame: Day 1

  21. TNFα Serum Concentrations

    Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113 TNF-alpha was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline TNFα values - Day 1 TNFα values/Day 1 TNFα values)\*100

    Time frame: Day 1

  22. Change From Baseline in Infiltrate/Histopathology Using Robarts Histopathology Index (RHI) at Week 8 and Week 16

    Infiltrate/Histopathology (Rectal/Sigmoidal Biopsies) using the Robarts Histopathology Index (RHI) Week 8 and Week 16 biopsies will be compared to biopsies at baseline to assess the disease evolution at a tissue level, based on the Robarts Histological Index. The score ranges from 0 (no disease activity) to 33 (severe disease activity) is based on evaluation of 4 parameters: chronic inflammatory infiltrate, lamina propria neutrophils and eosinophils, neutrophils in the epithelium and erosion and ulceration. A higher score indicates more severe disease.

    Time frame: Week 8 and Week 16

  23. Change From Baseline in Infiltrate/Histopathology - Geboes Score at Week 8 and Week 16

    The Geboes score is composed of 6 major grades that assess different aspects of the biopsy findings, with each grade having its own score range: 1. Structural Changes (Grade 0): Range: 0 (No changes) to 3 (Severe changes) 2. Chronic Inflammation (Grade 1): Range: 0 (No inflammation) to 3 (Severe inflammation) 3. Lamina Propria Neutrophils (Grade 2): Range: 0 (None) to 3 (Severe infiltration of neutrophils) 4. Neutrophils in the Epithelium (Grade 3): Range: 0 (None) to 3 (Severe neutrophil infiltration) 5. Crypt Destruction (Grade 4): Range: 0 (No destruction) to 3 (Severe crypt destruction) 6. Erosion and Ulcers (Grade 5): Range: 0 (None) to 3 (Severe erosion/ulceration) Subscales are summed across all 6 grades, final total score between 0 and 18 : * 0-5: Minimal or no inflammation * 6-10: Mild inflammation * 11-15: Moderate inflammation * 16-18: Severe inflammation or damage A higher score indicates more severe disease

    Time frame: Week 8 and Week 16

  24. IL-6 Serum Concentrations

    Serum samples from participants who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL6 was measured using the 8-plex assay on the ELLA Platform (Biotechne). All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-6 values - Day 1 IL-6 values/Day 1 IL-6 values)\*100

    Time frame: Day 8, Day 29, Day 57, and Day 113

  25. IL-10 Serum Concentrations

    Serum samples from patients who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL10 was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-10 values - Day 1 IL-10 values/Day 1 IL-10 values)\*100

    Time frame: Day 8, Day 29, Week 8 and Week 16

  26. IL-1B Serum Concentrations

    Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113). IL1beta was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-1B values - Day 1 IL-1B values/Day 1 IL-1B values)\*100

    Time frame: Day 8, Day 29, Day 57 and Day 113

  27. TNFα Serum Concentrations

    Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113 TNF-alpha was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline TNFα values - Day 1 TNFα values/Day 1 TNFα values)\*100

    Time frame: Day 8, Day 29, Day 57 and Day 113

07

Results

Posted Nov 28, 2025

Participant flow

A total of 355 patients consented to participate, 254 patients were randomized. A total of 253 patients were treated, 222 patients completed study treatment. 32 patients discontinued and 1 patient was randomized but did not receive study drug. One further patient was excluded from the Full Analysis Set (FAS) due to noncompliance with inclusion/exclusion criteria. A total of 252 patients were included in the FAS (64: ABX464 100mg q.d, 63: ABX464 50mg q.d, 61: ABX464 25mg q.d and 64: placebo).

Participant flow — Overall Study
MilestoneABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Started64636364
Treated64636264
Full analysis set64636164
Completed54535857
Not completed101057

Outcome measures

PrimaryReduction From Baseline in Modified Mayo Score (MMS) at Week 8

Reduction from baseline in Modified Mayo Score (MMS) MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease.

Time frame:
Week 8
Reported as:
Least squares mean · Score
Reduction From Baseline in Modified Mayo Score (MMS) at Week 8
ScoreABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Reduction From Baseline in Modified Mayo Score (MMS) at Week 8-2.9 (-3.4 to -2.5)-3.2 (-3.7 to -2.7)-3.1 (-3.6 to -2.6)-1.9 (-2.4 to -1.5)
SecondaryReduction From Baseline in MMS at Week 16

Reduction from baseline in Modified Mayo Score (MMS) MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease.

Time frame:
Week 16
Reported as:
Least squares mean · Score
Reduction From Baseline in MMS at Week 16
ScoreABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Overall-3.6 (-4.3 to -2.9)-3.2 (-3.9 to -2.5)-3.3 (-3.9 to -2.7)-2.4 (-2.9 to -1.8)
With Previous Biologics or JAK Inhibitors Exposure-3.3 (-4.1 to -2.6)-3.0 (-3.9 to -2.1)-2.9 (-3.7 to -2.1)-1.3 (-2.0 to -0.5)
Without Previous Biologics or JAK Inhibitors Exposure-3.6 (-4.8 to -2.3)-3.4 (-4.4 to -2.5)-3.7 (-4.6 to -2.8)-3.4 (-4.2 to -2.6)
SecondaryNumber of Participants in Clinical Remission Per MMS at Week 8

Number of participants who achieved clinical remission per Modified Mayo Score at Week 8 MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease. Clinical remission is defined as SFS ≤ 1, RBS of 0, and endoscopic subscore ≤ 1 (modified to exclude friability)

Time frame:
Week 8
Reported as:
Count of participants · Participants
Number of Participants in Clinical Remission Per MMS at Week 8
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants in Clinical Remission Per MMS at Week 81611168
SecondaryNumber of Participants in Clinical Remission Per MMS at Week 16

Number of participants who achieved clinical remission per Modified Mayo Score at Week 16 MMS is a composite score of UC disease activity based on the following 3 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools) to 3 (5 or more stools more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). 3. Endoscopic subscore, scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration). The overall MMS ranges from 0 to 9 where higher scores represent more severe disease. Clinical remission is defined as SFS ≤ 1, RBS of 0, and endoscopic subscore ≤ 1 (modified to exclude friability)

Time frame:
Week 16
Reported as:
Count of participants · Participants
Number of Participants in Clinical Remission Per MMS at Week 16
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants in Clinical Remission Per MMS at Week 167696
SecondaryNumber of Participants With Clinical Response at Week 8

Clinical response is defined as a reduction in MMS of at least 2 points and greater than or equal to 30 percent from baseline with an accompanying decrease in rectal bleeding sub-score of greater than or equal to 1 point or absolute rectal bleeding sub-score of less than or equal to 1 point.

Time frame:
Week 8
Reported as:
Count of participants · Participants
Number of Participants With Clinical Response at Week 8
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Clinical Response at Week 832373822
SecondaryNumber of Participants With Clinical Response at Week 16

Clinical response is defined as a reduction in MMS of at least 2 points and greater than or equal to 30 percent from baseline with an accompanying decrease in rectal bleeding sub-score of greater than or equal to 1 point or absolute rectal bleeding sub-score of less than or equal to 1 point.

Time frame:
Week 16
Reported as:
Count of participants · Participants
Number of Participants With Clinical Response at Week 16
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Clinical Response at Week 1619202520
SecondaryNumber of Participants With Endoscopic Improvement at Week 8

Endoscopic improvement is defined as an endoscopic subscore of 0 or 1 (excluding friability) Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher endoscopic score indicates more severe disease.

Time frame:
Week 8
Reported as:
Count of participants · Participants
Number of Participants With Endoscopic Improvement at Week 8
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Endoscopic Improvement at Week 82421208
SecondaryNumber of Participants With Endoscopic Improvement at Week 16

Endoscopic improvement is defined as an endoscopic subscore of 0 or 1 (excluding friability) Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher endoscopic score indicates more severe disease.

Time frame:
Week 16
Reported as:
Count of participants · Participants
Number of Participants With Endoscopic Improvement at Week 16
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Endoscopic Improvement at Week 161112119
SecondaryNumber of Participants With Mucosal Healing at Week 8

Mucosal healing is defined as endoscopic remission (overall mucosal appearance at endoscopy subscore=0) and histological remission (Geboes score \<2.0 based on rectal biopsy). The endoscopic subscore ranges from 0 (normal or inactive disease) to 3 (severe disease with spontaneous bleeding, ulceration). The Geboes histologic index includes seven histological features (architectural change, chronic inflammatory infiltrate, lamina propria neutrophils and eosinophils, neutrophils in epithelium, crypt destruction and erosion or ulcers). The Geboes score has 6 grades, each with 3-5 subgrades: Grade 0, structural change only; Grade 1, chronic inflammation; Grade 2, lamina propria neutrophils and eosinophils; Grade 3, neutrophils in epithelium; Grade 4, crypt destruction; and Grade 5, erosions or ulceration. A higher score is associated with higher disease activity.

Time frame:
Week 8
Reported as:
Count of participants · Participants
Number of Participants With Mucosal Healing at Week 8
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Mucosal Healing at Week 80102
SecondaryNumber of Participants With Mucosal Healing at Week 16

Mucosal healing is defined as endoscopic remission (overall mucosal appearance at endoscopy subscore=0) and histological remission (Geboes score \<2.0 based on rectal biopsy). The endoscopic subscore ranges from 0 (normal or inactive disease) to 3 (severe disease with spontaneous bleeding, ulceration). The Geboes histologic index includes seven histological features (architectural change, chronic inflammatory infiltrate, lamina propria neutrophils and eosinophils, neutrophils in epithelium, crypt destruction and erosion or ulcers). The Geboes score has 6 grades, each with 3-5 subgrades: Grade 0, structural change only; Grade 1, chronic inflammation; Grade 2, lamina propria neutrophils and eosinophils; Grade 3, neutrophils in epithelium; Grade 4, crypt destruction; and Grade 5, erosions or ulceration. A higher score is associated with higher disease activity.

Time frame:
Week 16
Reported as:
Count of participants · Participants
Number of Participants With Mucosal Healing at Week 16
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Mucosal Healing at Week 161000
SecondaryNumber of Participants With Reduction of Stool Frequency Relative to Baseline (Day 1)

Participants recorded stool frequency using an electronic subject diary on a daily basis. The stool frequency subscore (SFS) ranges from 0 to 3 according to the following scale: Score 0: Normal number of stools Score 1: 1 to 2 stools per day more than normal Score 2: 3 to 4 stools per day more than normal Score 3: 5 or more stools per day more than normal Decreasing score indicates improvement.

Time frame:
Day 8, Day 29, Day 57, Day 85, Day 113, and Day 120 (End of Study)
Reported as:
Count of participants · Participants
Number of Participants With Reduction of Stool Frequency Relative to Baseline (Day 1)
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Day 818221412
Day 2934363526
Week 8 (Day 57)39373937
Day 8541393730
Week 16 (Day 113)44394238
End of study (Day 120)3411
SecondaryNumber of Participants With Reduction of Rectal Bleeding Frequency Relative to Baseline

Participants recorded rectal bleeding in an electronic subject diary on a daily basis. Rectal bleeding score (RBS) is taken as the worst subscore of the three most recent scores within 7 days prior to the visit. The rectal bleeding subscore ranges from 0 to 3 according to the following scale: Score 0: No blood seen Score 1: Streaks of blood with stool less than half the time Score 2: Obvious blood with stool most of the time Score 3: Blood alone passed A lower score represents an improvement in rectal bleeding.

Time frame:
Day 8, Day 29, Day 57, Day 85, Day 113, and Day 120 (End of Study)
Reported as:
Count of participants · Participants
Number of Participants With Reduction of Rectal Bleeding Frequency Relative to Baseline
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Day 825232416
Day 2944383924
Week 8 (Day 57)48444633
Day 8547394435
Week 16 (Day 113)50454637
End of study (Day 120)3411
SecondaryPartial Modified Mayo Score Change From Baseline

Partial Modified Mayo Score (pMMS) Change from baseline The pMMS is a composite score of UC disease activity based on the following 2 subscores: 1. Stool frequency subscore (SFS), scored from 0 (normal number of stools per day) to 3 (5 or more stools per day more than normal). 2. Rectal bleeding subscore (RBS), scored from 0 (no blood seen) to 3 (blood alone passed). The overall pMMS score ranges from 0 to 6 with higher scores representing more severe disease.

Time frame:
Day 8, Day 29, Day 57, Day 85, Day 113, and Day 120 (End of Study)
Reported as:
Least squares mean · Score
Partial Modified Mayo Score Change From Baseline
ScoreABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Day 8-0.7 (-1.0 to -0.3)-0.8 (-1.1 to -0.4)-0.7 (-1.0 to -0.4)-0.4 (-0.7 to -0.1)
Day 29-1.8 (-2.1 to -1.5)-1.8 (-2.2 to -1.5)-1.8 (-2.1 to -1.4)-0.9 (-1.3 to -0.6)
Week 8 (Day 57)-2.2 (-2.6 to -1.9)-2.2 (-2.5 to -1.9)-2.3 (-2.6 to -2.0)-1.6 (-1.9 to -1.3)
Day 85-2.4 (-2.8 to -2.1)-2.3 (-2.6 to -2.0)-2.3 (-2.7 to -2.0)-1.6 (-1.9 to -1.3)
Week 16 (Day 113)-2.8 (-3.1 to -2.4)-2.4 (-2.8 to -2.1)-2.6 (-3.0 to -2.3)-2.0 (-2.3 to -1.7)
End of Study (Day 120)-1.1 (-2.1 to -0.2)-1.9 (-2.9 to -1.0)-3.3 (-5.7 to -0.9)-1.2 (-2.9 to 0.5)
SecondaryNumber of Participants With Reduction Relative to Baseline in Fecal Calprotectin at Weeks 8 and 16

Fecal Calprotectin (FC) is a non-invasive surrogate marker of inflammation in the small intestine and levels below 250 ug/g is associated with mucosal healing. FC levels were measured using enzyme-linked immunosorbent assay (ELISA) and/or a validated quantitative rapid test. Outcome will be measured based on a reduction in FC relative to baseline values.

Time frame:
Week 8 and Week 16
Reported as:
Count of participants · Participants
Number of Participants With Reduction Relative to Baseline in Fecal Calprotectin at Weeks 8 and 16
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Week 833353326
Week 1637353722
SecondaryNumber of Participants With Reduction Relative to Baseline in C Reactive Protein at Weeks 8 and 16

CRP is an acute-phase protein which provides an objective criterion of inflammatory activity. CRP has a short half-life (19 hours) and therefore rises early after the onset of inflammation and rapidly decreases after resolution of the inflammation. It is induced by interleukin-6, TNF-alpha and other pro-inflammatory cytokines that are produced within the intestinal lamina propria. Outcome will be measured based on a reduction in CRP relative to baseline values.

Time frame:
Week 8 and Week 16
Reported as:
Count of participants · Participants
Number of Participants With Reduction Relative to Baseline in C Reactive Protein at Weeks 8 and 16
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Week 8 (Day 57)31283929
Week 16 (Day 113)31293729
SecondarymiRNA-124 Expression (Copy Number) in Whole Blood at Week 8 and Week 16

Absolute quantification (QuantaSoft Pro) of the miR-124 copy number was performed at Week 8 and Week 16 using droplet digital PCR technology (ddPCR) on whole blood samples. "0" in the placebo column means "no signal", so BLQ (Below the level of quantification).

Time frame:
Week 8 and Week 16
Reported as:
Mean · copies number/cell
miRNA-124 Expression (Copy Number) in Whole Blood at Week 8 and Week 16
copies number/cellABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Week 813753 ± 121428517 ± 62524598 ± 1134828.93 ± 146.4
Week 1613268 ± 111347723 ± 74774154 ± 527323.79 ± 94.69
SecondaryIL-6 Serum Concentrations

Serum samples from participants who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL6 was measured using the 8-plex assay on the ELLA Platform (Biotechne). All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-6 values - Day 1 IL-6 values/Day 1 IL-6 values)\*100

Time frame:
Day 1
Reported as:
Mean · Percentage of IL-6
IL-6 Serum Concentrations
Percentage of IL-6ABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
IL-6 Serum Concentrations100 ± 10.77100 ± 13.36100 ± 19.37100 ± 28.77
SecondaryNumber of Participants With Endoscopic Remission at Week 8

Endoscopic remission is defined as an endoscopic subscore of 0. Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher score represents more severe disease.

Time frame:
Week 8
Reported as:
Count of participants · Participants
Number of Participants With Endoscopic Remission at Week 8
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Endoscopic Remission at Week 82545
SecondaryNumber of Participants With Endoscopic Remission at Week 16

Endoscopic remission is defined as an endoscopic subscore of 0. Endoscopies were assessed by a blinded central reader and scored according to the following scale: 0 = Normal or inactive disease; 1. = Mild disease (erythema, decreased vascular pattern); 2. = Moderate disease (marked erythema, lack of vascular pattern, any friability, erosions); 3. = Severe disease (spontaneous bleeding, ulceration). A higher score represents more severe disease.

Time frame:
Week 16
Reported as:
Count of participants · Participants
Number of Participants With Endoscopic Remission at Week 16
ParticipantsABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Number of Participants With Endoscopic Remission at Week 161123
SecondaryIL-10 Serum Concentrations

Serum samples from patients who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL10 was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-10 values - Day 1 IL-10 values/Day 1 IL-10 values)\*100

Time frame:
Day 1
Reported as:
Mean · Percentage of IL-10
IL-10 Serum Concentrations
Percentage of IL-10ABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
IL-10 Serum Concentrations100 ± 8.982100 ± 6.989100 ± 18.98100 ± 17.54
SecondaryIL-1B Serum Concentrations

Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113). IL1beta was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-1B values - Day 1 IL-1B values/Day 1 IL-1B values)\*100

Time frame:
Day 1
Reported as:
Mean · Percentage of IL-1B
IL-1B Serum Concentrations
Percentage of IL-1BABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
IL-1B Serum Concentrations100 ± 6.514100 ± 8.988100 ± 7.043100 ± 4.87
SecondaryTNFα Serum Concentrations

Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113 TNF-alpha was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline TNFα values - Day 1 TNFα values/Day 1 TNFα values)\*100

Time frame:
Day 1
Reported as:
Mean · Percentage of TNFα
TNFα Serum Concentrations
Percentage of TNFαABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
TNFα Serum Concentrations100 ± 18.79100 ± 9.313100 ± 19100 ± 5.473
SecondaryChange From Baseline in Infiltrate/Histopathology Using Robarts Histopathology Index (RHI) at Week 8 and Week 16

Infiltrate/Histopathology (Rectal/Sigmoidal Biopsies) using the Robarts Histopathology Index (RHI) Week 8 and Week 16 biopsies will be compared to biopsies at baseline to assess the disease evolution at a tissue level, based on the Robarts Histological Index. The score ranges from 0 (no disease activity) to 33 (severe disease activity) is based on evaluation of 4 parameters: chronic inflammatory infiltrate, lamina propria neutrophils and eosinophils, neutrophils in the epithelium and erosion and ulceration. A higher score indicates more severe disease.

Time frame:
Week 8 and Week 16
Reported as:
Least squares mean · score on a scale
Change From Baseline in Infiltrate/Histopathology Using Robarts Histopathology Index (RHI) at Week 8 and Week 16
score on a scaleABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Week 8-7.3 (-9.9 to -4.8)-5.9 (-8.5 to -3.3)-7.3 (-9.7 to -4.9)-3.4 (-5.8 to -1.0)
Week 16-7.6 (-11.2 to -4.0)-5.8 (-10.0 to -1.6)-8.0 (-11.2 to -4.7)-2.8 (-5.9 to 0.3)
SecondaryChange From Baseline in Infiltrate/Histopathology - Geboes Score at Week 8 and Week 16

The Geboes score is composed of 6 major grades that assess different aspects of the biopsy findings, with each grade having its own score range: 1. Structural Changes (Grade 0): Range: 0 (No changes) to 3 (Severe changes) 2. Chronic Inflammation (Grade 1): Range: 0 (No inflammation) to 3 (Severe inflammation) 3. Lamina Propria Neutrophils (Grade 2): Range: 0 (None) to 3 (Severe infiltration of neutrophils) 4. Neutrophils in the Epithelium (Grade 3): Range: 0 (None) to 3 (Severe neutrophil infiltration) 5. Crypt Destruction (Grade 4): Range: 0 (No destruction) to 3 (Severe crypt destruction) 6. Erosion and Ulcers (Grade 5): Range: 0 (None) to 3 (Severe erosion/ulceration) Subscales are summed across all 6 grades, final total score between 0 and 18 : * 0-5: Minimal or no inflammation * 6-10: Mild inflammation * 11-15: Moderate inflammation * 16-18: Severe inflammation or damage A higher score indicates more severe disease

Time frame:
Week 8 and Week 16
Reported as:
Least squares mean · Score change from baseline
Change From Baseline in Infiltrate/Histopathology - Geboes Score at Week 8 and Week 16
Score change from baselineABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Week 8-4.8 (-6.3 to -3.3)-3.3 (-4.9 to -1.8)-4.1 (-5.6 to -2.7)-1.9 (-3.4 to -0.5)
Week 16-4.4 (-6.5 to -2.3)-3.9 (-6.3 to -1.5)-4.7 (-6.6 to -2.8)-1.3 (-3.1 to 0.5)
SecondaryIL-6 Serum Concentrations

Serum samples from participants who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL6 was measured using the 8-plex assay on the ELLA Platform (Biotechne). All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-6 values - Day 1 IL-6 values/Day 1 IL-6 values)\*100

Time frame:
Day 8, Day 29, Day 57, and Day 113
Reported as:
Mean · Percent Change
IL-6 Serum Concentrations
Percent ChangeABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Day 8166.4 ± 20.9896.45 ± 9.034103.6 ± 8.641132.7 ± 15.18
Day 29117 ± 10.9293.36 ± 12.1989.31 ± 8.608128.2 ± 10.85
Week 8 (Day 57)118.9 ± 11.3150.6 ± 47.0689.75 ± 8.662125.7 ± 17.11
Week 16 (Day 113)108.3 ± 14.23170.1 ± 56.498.29 ± 12.03131.8 ± 16.97
SecondaryIL-10 Serum Concentrations

Serum samples from patients who received ABX464 (25, 50 or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57, and Day 113). IL10 was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-10 values - Day 1 IL-10 values/Day 1 IL-10 values)\*100

Time frame:
Day 8, Day 29, Week 8 and Week 16
Reported as:
Mean · Percent Change
IL-10 Serum Concentrations
Percent ChangeABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Day 8100.3 ± 4.596102.3 ± 5.827101 ± 4.288100.1 ± 3.918
Day 2998.71 ± 6.62687.22 ± 3.63891.40 ± 4.519102.5 ± 4.728
Week 8 (Day 57)96.00 ± 5.59099.30 ± 7.43189.30 ± 4.28994.18 ± 4.886
Week 16 (Day 113)103.9 ± 7.43592.50 ± 4.87991.24 ± 4.91191.85 ± 5.943
SecondaryIL-1B Serum Concentrations

Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113). IL1beta was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline IL-1B values - Day 1 IL-1B values/Day 1 IL-1B values)\*100

Time frame:
Day 8, Day 29, Day 57 and Day 113
Reported as:
Mean · Percent Change
IL-1B Serum Concentrations
Percent ChangeABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Day 8102.8 ± 7.453118.2 ± 10.44103.7 ± 5.562111 ± 5.203
Day 29115 ± 9.424101.3 ± 5.435138 ± 41.41112.6 ± 7.052
Week 8 (Day 57)105.3 ± 5.735100.3 ± 6.4999 ± 6.605124.1 ± 12.24
Week 16 (Day 113)102.4 ± 6.513137.5 ± 26.11124.1 ± 12.24109 ± 7.042
SecondaryTNFα Serum Concentrations

Serum samples from patients who received ABX464 (25, 50, or 100 mg) or placebo were collected during 5 visits (Day 1, Day 8, Day 29, Day 57 and Day 113 TNF-alpha was measured using the 8-plex assay on the ELLA Platform. All samples were tested in duplicate at the minimum required dilution. Baseline (Day 1) values are calculated as below: x1/arithmetic mean of baseline values x 100, where the arithmetic mean is defined by (x1 + x2+...+xn)/n (summing all baseline values and dividing by the total number of values n) The post baseline values are calculated as follow: post-baseline TNFα values - Day 1 TNFα values/Day 1 TNFα values)\*100

Time frame:
Day 8, Day 29, Day 57 and Day 113
Reported as:
Mean · Percent Change
TNFα Serum Concentrations
Percent ChangeABX464 100 mgABX464 50 mgABX464 25 mgMatching Placebo
Day 898.8 ± 3.42396.77 ± 5.84496.42 ± 4.55299.7 ± 2.739
Day 2999.62 ± 5.37491.30 ± 4.67692.64 ± 4.629110.2 ± 10.12
Week 8 (Day 57)105.5 ± 9.67595.55 ± 4.50397.51 ± 4.874102.6 ± 4.873
Week 16 (Day 113)103.7 ± 7.610108.6 ± 10.61100.1 ± 7.194111.4 ± 7.725

Adverse events

Collected over TEAEs and SAEs were collected from enrollment to end of study: up to 24 weeks in total, including 4 weeks screening (prior the first dose of study drug), 16 weeks of treatment, and 4 weeks safety follow-up (28 days after last dose of study drug). All-cause mortality was reported from enrollment to end of study: up to 24 weeks in total, including 4 weeks screening (prior the first dose of study drug), 16 weeks of treatment, and 4 weeks safety follow-up (28 days after last dose of study drug).. Non-serious events are listed at a 1% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
ABX464, 100mg0/64 (0%)4/64 (6.3%)45/64 (70.3%)
ABX464, 50 mg0/63 (0%)4/63 (6.3%)38/63 (60.3%)
ABX464, 25mg0/62 (0%)1/62 (1.6%)33/62 (53.2%)
Matching Placebo0/64 (0%)4/64 (6.3%)30/64 (46.9%)
Most frequent serious events
Most frequent serious events
EventABX464, 100mgABX464, 50 mgABX464, 25mgMatching Placebo
Colitis ulcerativeGastrointestinal disorders1/641/630/623/64
AnaemiaBlood and lymphatic system disorders0/640/631/620/64
Abdominal painGastrointestinal disorders0/641/630/620/64
AppendicitisInfections and infestations0/641/630/620/64
DehydratationMetabolism and nutrition disorders0/641/630/620/64
RashSkin and subcutaneous tissue disorders0/641/630/620/64
PancreatitisGastrointestinal disorders1/640/630/620/64
Angina pectorisCardiac disorders1/640/630/621/64
Myocardial infarctionCardiac disorders1/640/630/620/64
Back painMusculoskeletal and connective tissue disorders1/640/630/620/64
Most frequent other events
Showing 10 of 136
Most frequent other events
EventABX464, 100mgABX464, 50 mgABX464, 25mgMatching Placebo
HeadacheNervous system disorders27/6419/6313/625/64
NauseaGastrointestinal disorders9/644/635/624/64
VomitingGastrointestinal disorders5/642/631/621/64
ArthralgiaMusculoskeletal and connective tissue disorders5/641/631/623/64
MyalgiaMusculoskeletal and connective tissue disorders5/640/630/620/64
Abdominal pain upperGastrointestinal disorders4/643/633/620/64
Colitis ulcerativeGastrointestinal disorders0/643/630/621/64
NasopharyngitisInfections and infestations1/643/631/620/64
ConstipationGastrointestinal disorders0/640/632/620/64
DispepsiaGastrointestinal disorders0/640/632/620/64

Baseline characteristics

Age, Categorical
Age, Categorical(Participants)ABX464 100 mgABX464 50 mgABX464 25mgMatching PlaceboTotal
<=18 years00000
Between 18 and 65 years61605660237
>=65 years335415
Age, Continuous
Age, Continuous(Years)ABX464 100 mgABX464 50 mgABX464 25mgMatching PlaceboTotal
Mean42.2 ± 12.3440.2 ± 13.9441.5 ± 14.1641.1 ± 14.4341.2 ± 13.67
Sex: Female, Male
Sex: Female, Male(Participants)ABX464 100 mgABX464 50 mgABX464 25mgMatching PlaceboTotal
Female23362124104
Male41274040148
Race and Ethnicity Not Collected
Race and Ethnicity Not Collected(Participants)ABX464 100 mgABX464 50 mgABX464 25mgMatching PlaceboTotal
Count of participants————0
Region of Enrollment
Region of Enrollment(participants)ABX464 100 mgABX464 50 mgABX464 25mgMatching PlaceboTotal
Hungary555722
Czechia264214
United States01012
Ukraine1276732
Spain10001
Canada11215
Austria11136
Belgium42028
Poland1616182070
Italy526720
Slovakia375318
Slovenia11103
France887730
Serbia03205
Germany534416
Baseline Modified Mayo Score (MMS)
Baseline Modified Mayo Score (MMS)(Participants)ABX464 100 mgABX464 50 mgABX464 25mgMatching PlaceboTotal
Baseline MMS: 400011
Baseline MMS: 5 to 61716172171
Baseline MMS: 7 to 947474442180
08

Study locations

130 sites
  • UCSD Health System
    San Diego, California 92103, United States
  • Atlanta Center for Gastroenterology, P.C
    Decatur, Georgia 30033, United States
  • Central Texas Clinical Research, LLC
    Austin, Texas 78705, United States
  • Southern Star Research Institute, LLC
    San Antonio, Texas 78212, United States
  • Medizinische Universität Innsbruck
    Innsbruck, Austria
  • Klinikum Klagenfurt am Wörthersee
    Klagenfurt, Austria
  • Ordensklinikum Linz GmbH - Barmherzige Schwestern
    Linz, Austria
  • AKH - Medizinische Universität Wien
    Vienna, Austria
  • Gomel Regional Clinical Hospital
    Homyel, Belarus
  • Minsk city diagnostic center
    Minsk, Belarus
  • Regional Clinical Hospital
    Minsk, Belarus
  • Vitebsk Regional Clinical Hospital
    Vitebsk, Belarus
  • Vitebsk regoinal clinical specialized center
    Vitebsk, Belarus
  • AZ Sint-Lucas
    Bruges, Belgium
  • C. H. U. St-Pierre
    Brussels, Belgium
  • UZA
    Edegem, Belgium
  • Universitair Ziekenhuis Gent
    Ghent, Belgium
  • UZ Leuven
    Leuven, Belgium
  • Brandon Medical Arts Clinic
    Brandon, Canada
  • South Edmonton Gastroenterology
    Edmonton, Canada
  • LHSC - Victoria Hospital
    London, Canada
  • The Ottawa Hospital - General Campus
    Ottawa, Canada
  • Allen Whey Khye Lim Professional Corporation
    Saskatoon, Canada
  • Mount Sinai Hospital
    Toronto, Canada
  • Fakultni nemocnice u sv. Anny v Brne
    Brno, Czechia
  • Hepato-Gastroenterologie HK s.r.o.
    Hradec Králové, Czechia
  • MUDr. GREGAR s.r.o.
    Olomouc, Czechia
  • Fakultni nemocnice Ostrava
    Ostrava-Kunčice, Czechia
  • Nemocnice Na Bulovce
    Prague, Czechia
  • Thomayerova nemocnice
    Prague, Czechia
  • Nemocnice Slany
    Slaný, Czechia
  • CHU Amiens - Hopital Sud
    Amiens, France
  • CHU Besançon - Hôpital Jean Minjoz
    Besançon, France
  • CHU Clermont Ferrand - Hôpital d'Estaing
    Clermont-Ferrand, France
  • Hôpital Beaujon
    Clichy, France
  • CHU de Grenoble - Hôpital Nord
    Grenoble, France
  • Centre Hospitalier Départemental Les Oudairies
    La Roche-sur-Yon, France
  • CHU Lille - Hôpital Claude Huriez
    Lille, France
  • Hôpital Nord - CHU Marseille
    Marseille, France
  • Hopital Saint Eloi
    Montpellier, France
  • CHU Nantes - Hôtel Dieu
    Nantes, France
  • CHU Nice - Hôpital de l'Archet 2
    Nice, France
  • CHU Reims - Hôpital Robert Debré
    Reims, France
  • CHU Rennes - Hôpital Pontchaillou
    Rennes, France
  • CHU de Rouen - Hôpital Charles Nicolle
    Rouen, France
  • CHU Saint Etienne - Hôpital Nord
    Saint-Etienne, France
  • CHU Strasbourg - Hôpital Hautepierre
    Strasbourg, France
  • Hopital Rangueil
    Toulouse, France
  • Hôpital de Brabois Adultes
    Vandœuvre-lès-Nancy, France
  • Charite Universitaetsmedizin Berlin - Campus Benjamin Franklin
    Berlin, Germany
  • Florence-Nightingale-Krankenhaus-Diakonie Kaiserswerth
    Düsseldorf, Germany
  • Klinikum der Johann Wolfgang Goethe-Universitaet
    Frankfurt, Germany
  • Studiengesellschaft BSF Unternehmergesellschaft haftungsbeschraenkt
    Halle, Germany
  • Universitaetsklinikum Halle (Saale)
    Halle, Germany
  • Medizinische Hochschule Hannover
    Hanover, Germany
  • Johanna-Etienne-Krankenhaus
    Neuss, Germany
  • Tumorzentrum Nordthueringen MVZ GmbH
    Nordhausen, Germany
  • Dr. Tasso Bieler
    Riesa, Germany
  • Universitaetsklinikum Ulm
    Ulm, Germany
  • DRC Gyogyszervizsgalo Kozpont Kft.
    Balatonfüred, Hungary
  • Obudai Egeszsegugyi Centrum Kft.
    Budapest, Hungary
  • Pannonia Maganorvosi Centrum
    Budapest, Hungary
  • Semmelweis Egyetem
    Budapest, Hungary
  • Debreceni Egyetem
    Debrecen, Hungary
  • Vasutegeszsegugyi Kft. - Debreceni Egeszsegugyi Kozpont
    Debrecen, Hungary
  • Petz Aladar Megyei Oktato Korhaz
    Győr, Hungary
  • Azienda Ospedaliera Universitaria Policlinico Sant'Orsola Malpighi
    Bologna, Italy
  • Fondazione Poliambulanza Istituto Ospedaliero
    Brescia, Italy
  • Azienda Ospedaliero Universitaria Mater Domini
    Catanzaro, Italy
  • I.R.C.C.S Policlinico San Donato
    Milan, Italy
  • Ospedale Sacro Cuore Don Calabria
    Negrar, Italy
  • Azienda Ospedaliera di Padova
    Padova, Italy
  • Azienda Ospedaliero Universitaria Policlinico Paolo Giaccone
    Palermo, Italy
  • Azienda Ospedaliero Universitaria Pisana (Presidio di Cisanello)
    Pisa, Italy
  • Fondazione Policlinico Universitario Agostino Gemelli IRCCS
    Roma, Italy
  • Istituto Clinico Humanitas
    Rozzano, Italy
  • Szpital Uniwersytecki nr 2 im.dr J. Biziela
    Bydgoszcz, Poland
  • Uniwersyteckie Centrum Kliniczne
    Gdansk, Poland
  • Centrum Medyczne Plejady
    Krakow, Poland
  • Santa Familia Centrum Badan, Profilaktyki i Leczenia
    Lodz, Poland
  • Wojskowy Szpital Kliniczny w Lublinie
    Lublin, Poland
  • Trialmed CRS
    Piotrkow Trybunalski, Poland
  • Centrum Medyczne Grunwald
    Poznan, Poland
  • KO-MED Centra Kliniczne Pulawy
    Puławy, Poland
  • Gabinet Lekarski Bartosz Korczowski
    Rzeszów, Poland
  • Centrum Zdrowia MDM
    Warsaw, Poland
  • Nzoz Vivamed
    Warsaw, Poland
  • Centrum Zdrowia Tuchow Sp. z o.o.
    Wierzchosławice, Poland
  • Centrum Badan Klinicznych Piotr Napora Lekarze Spolka Partnerska
    Wroclaw, Poland
  • Centrum Medyczne Oporow
    Wroclaw, Poland
  • LexMedica
    Wroclaw, Poland
  • Clinical Center " Dr Dragisa Misovic Dedinje"
    Belgrade, Serbia
  • Clinical Center Bezanijska Kosa
    Belgrade, Serbia
  • Clinical Center Zvezdara
    Belgrade, Serbia
  • General Hospital Uzice
    Užice, Serbia
  • General Hospital "Djordje Joanovic"
    Zrenjanin, Serbia
  • Alian s.r.o.
    Bardejov, Slovakia
  • Cliniq s.r.o.
    Bratislava, Slovakia
  • Gastromedic, s.r.o.
    Nové Zámky, Slovakia
  • Gastro I, s.r.o.
    Prešov, Slovakia

Showing the first 100 of 130 sites across 17 countries.

09

References and documents

Study documents

  • Study protocol · Jun 1, 2020
  • Statistical analysis plan · May 10, 2021

Documents are hosted by the registry — open the source record to download them.

Individual participant data

Plan to share: No

10

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Nov 28, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT03760003
Lead sponsor
Abivax S.A.
Responsible party
Sponsor
First posted
Nov 30, 2018
Start date
Aug 13, 2019
Primary completion
Apr 1, 2021
Completion
Apr 16, 2021
Results posted
Nov 28, 2025
Last update
Nov 28, 2025

Study contacts

Séverine VERMEIRE, MD
principal investigator · Universitaire Ziekenhuizen KU Leuven

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Nov 2025. You cannot join it, but the record below documents what was studied.

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