The ANB033 clinical trial offers an early hint that blocking one shared immune-signalling receptor could shield the small intestine from gluten. On 12 October 2026, First Tracks Biotherapeutics announced top-line results from the gluten-challenge cohort of a Phase 1b study of ANB033 in celiac disease. In 32 evaluable patients, the antibody limited the usual fall in the villus-to-crypt ratio, held back the rise in gut-lining immune cells and kept symptom scores from climbing, all relative to placebo, according to the company.
This report looks at the biology the drug targets, how the study was built, the numbers, and the questions a Phase 1b result cannot answer.
ANB033 clinical trial: key takeaways
- ANB033 is a subcutaneous antibody that blocks CD122, the common beta subunit of the IL-15 and IL-2 receptors.
- The randomised, placebo-controlled cohort had 32 evaluable patients: 17 on ANB033 and 15 on placebo.
- A 14-day challenge of 6 grams of gluten a day was used, with the main analysis at week 6.
- Placebo-adjusted differences were statistically significant on all three tissue measures, per the company.
- Dose, long-term safety and real-world benefit remain unknown.
The biology behind the ANB033 clinical trial: why target CD122
In celiac disease, gluten triggers an immune attack on the lining of the small intestine. As the NIDDK explains, the standard treatment is a gluten-free diet. IL-15 and IL-2 are signalling proteins that help certain immune cells survive and become active. Both use CD122 as part of their receptors, so a drug that blocks CD122 can dampen both pathways at once.
According to the company, ANB033 inhibits IL-15 and IL-2 signalling and reduces subsets of CD8+ and CD4+ T cells, natural killer cells and ILC2s. The idea is to cut back the cytolytic CD8 T cells, including the intraepithelial lymphocytes that gather in the gut lining, along with inflammatory cytokine release. On the investor call, management said an earlier healthy-volunteer study showed a single dose cut CD122-positive CD8 T cells by 74% and CD122-positive NK cells by 98% versus almost no change on placebo. These are company-reported figures.
How the ANB033 clinical trial was designed
Cohort 1 was a randomised, placebo-controlled gluten challenge. Participants received subcutaneous loading doses at weeks 0, 2 and 4, then ate 6 grams of gluten daily for 14 days, given as two cookies. On the call, management said patients were required to have a baseline Vh:Cd ratio above 2, and that the average baseline was 2.75 in both groups. Thirty-four people were in the safety set; 32 were evaluable. The dose has not been disclosed.
Results: the ANB033 clinical trial tissue data
The villus height to crypt depth ratio (Vh:Cd) is a standard way of grading flattening of the intestinal folds. It changed by -0.66 on placebo and -0.17 on ANB033, a placebo-adjusted difference of +0.49 (p=0.009). Intraepithelial lymphocyte density rose by 18.83 on placebo and moved by -1.20 on ANB033 (difference -20.03, p below 0.001). A composite score, VCIEL, changed by -3.59 versus -0.25 (difference +3.33, p=0.002).
Put plainly, the placebo group showed the damage that two weeks of gluten normally causes in people with celiac disease, and the ANB033 group showed much less of it. That is what a protective drug would be expected to look like, but it is also exactly the question a larger trial must answer again.
Symptoms and safety in the ANB033 clinical trial
Participants scored abdominal pain, bloating, nausea, diarrhoea and tiredness each day. Symptom scores were significantly lower on ANB033 from day 1 to day 7, and moderate-to-severe symptoms from day 1 to day 12. Symptom-relief medicine was used by 47% of placebo patients and 6% of ANB033 patients.
There were no serious adverse events. Any adverse event occurred in 88.9% on ANB033 and 100% on placebo; moderate events in 16.7% and 75.0%. Injection-site redness was more frequent with ANB033, at 27.8% versus 12.5%. No ANB033 patient discontinued because of an adverse event. The company describes the profile as favourable with no safety signals to date.
What the company said about the ANB033 clinical trial
Daniel Faga, president and chief executive, said ANB033 achieved a statistically significant and clinically meaningful protective effect. Dr Benjamin Lebwohl of Columbia University Irving Medical Center, quoted in the release, called it remarkable to see both symptom prevention and a Vh:Cd benefit in the same study. Chief medical officer Paul Lizzul said the consistency of tissue and symptom findings strengthens confidence in the underlying biology. On the call, management also called this a small study and said cross-trial comparisons are limited.
Risks and caveats for the ANB033 clinical trial
- Cohort size: 32 evaluable patients cannot rule out chance findings or rare side effects.
- Short exposure: a 14-day challenge is not the same as years of occasional exposure.
- Translational data, such as IL-2 kinetics, were not yet available according to management.
- Dampening immune pathways may carry infection or other risks that only longer studies can measure.
- Results come from the company and await peer review. Standard forward-looking warnings are in its filings on the SEC’s EDGAR database.
In our assessment, the most useful reading is that the biology is behaving as hoped. The step from “protects the gut for two weeks in a supervised setting” to “improves life with celiac disease” is large, and later cohorts will have to make it.
What to watch next after the ANB033 clinical trial
- The full presentation at ICDS in Melbourne in November 2026.
- Cohort 2, which tests mucosal healing over 12 weeks without a gluten challenge; top-line data are expected in the first quarter of 2027.
- Regulatory talks ahead of a late-stage celiac trial anticipated in 2027. ANB033 already has the FDA’s Fast Track designation.
- A separate Phase 1b cohort in eosinophilic esophagitis, with 50 patients and data expected in the third quarter of 2027.
For another example of the FDA’s expedited tools, see our report on a Fast Track designation for SAB-142, and browse pharmaceutical coverage.
Frequently asked questions
What did the ANB033 clinical trial test?
Whether ANB033 could protect the small intestine and prevent symptoms during a 14-day gluten challenge in people with celiac disease.
What is CD122?
A receptor subunit shared by the IL-15 and IL-2 receptors. ANB033 is designed to block it.
Is ANB033 approved anywhere?
No. It is investigational. It has received the FDA’s Fast Track designation, which is not an approval.
When will bigger trial data arrive?
Cohort 2 data are expected in the first quarter of 2027, with a late-stage celiac trial anticipated to start in 2027.
How we reported this: we relied on First Tracks Biotherapeutics’ announcement of 12 October 2026 and its investor call, plus the NIDDK for background. Figures attributed to the call are management’s. Last updated: 15 October 2026. This article is news reporting and not medical advice.
