Duvakitug Anti-TL1A Antibody Shows 47% Endoscopic Remission in Crohn's Disease Phase 2b RELIEVE Trial

What Is Duvakitug and What Is the TL1A Pathway?

Duvakitug (TEV-48574/SAR447189) is a humanized IgG4 monoclonal antibody that selectively binds and neutralizes TL1A (also known as TNFSF15), a cytokine belonging to the tumor necrosis factor superfamily. Developed by Teva Pharmaceuticals and Sanofi, it is one of several anti-TL1A antibodies in clinical development for inflammatory bowel disease. TL1A signals through its receptor DR3 (death receptor 3, also known as TNFRSF25), which is expressed on T cells, innate lymphoid cells (ILCs), macrophages, and fibroblasts within the intestinal mucosa. Activation of the TL1A/DR3 axis drives multiple pathological processes in Crohn's disease: it promotes Th1 and Th17 differentiation, stimulates ILC2-mediated type 2 immune responses, enhances production of pro-inflammatory cytokines including IFN-gamma and IL-17, and directly activates intestinal fibroblasts to produce collagen and extracellular matrix components contributing to stricture formation.

Genetic studies have provided compelling evidence for TL1A's central role in inflammatory bowel disease. Genome-wide association studies (GWAS) have identified multiple single nucleotide polymorphisms (SNPs) in the TNFSF15 gene locus (encoding TL1A) that confer increased susceptibility to both Crohn's disease and ulcerative colitis across diverse ethnic populations. The TNFSF15 risk haplotype is associated with increased TL1A expression, and patients carrying these variants exhibit more aggressive disease phenotypes with higher rates of stricturing and penetrating complications. By targeting this genetically validated pathway, duvakitug addresses a fundamental upstream driver of intestinal inflammation and fibrosis that is not directly modulated by existing biologic therapies.

How Effective Was Duvakitug in the RELIEVE UCCD Phase 2b Trial?

The RELIEVE UCCD trial was a randomized, double-blind, placebo-controlled, dose-ranging Phase 2b study that included a cohort of adults with moderate-to-severe Crohn's disease (CDAI 220-450, with active endoscopic disease confirmed by SES-CD). Patients were randomized to multiple dose levels of duvakitug administered subcutaneously every 4 weeks, or placebo. The trial enrolled patients across several clinical sites, with a substantial proportion having experienced prior biologic failure (TNF inhibitors, vedolizumab, or ustekinumab), representing a treatment-refractory population.

The trial met its primary efficacy endpoints with statistical significance. At the highest evaluated dose, endoscopic response (defined as SES-CD reduction of 50% or greater from baseline) was achieved in approximately 48% of patients compared to approximately 13% on placebo. Clinical remission (defined as CDAI < 150) was also significantly higher in the duvakitug groups compared to placebo. Among biologic-experienced patients, duvakitug continued to demonstrate robust efficacy, suggesting meaningful clinical benefit even in difficult-to-treat patients who had failed prior therapies.

A clear dose-response relationship was observed across all endpoints, with higher doses producing greater rates of clinical remission and endoscopic response. These results were presented at the American College of Gastroenterology (ACG) 2025 annual meeting and at the European Crohn's and Colitis Organisation (ECCO) 2025 congress. The magnitude of the endoscopic response compares favorably with published Phase 3 induction data for currently available biologics, though cross-trial comparisons must be interpreted with caution due to differences in patient populations and trial designs.

What Are the Side Effects of Duvakitug?

The safety profile of duvakitug in the RELIEVE UCCD trial was favorable. According to data presented by Teva and Sanofi, overall adverse event rates were similar across treatment and placebo groups. The most commonly reported adverse events included nasopharyngitis, headache, and arthralgia, all at rates comparable to placebo. Crohn's disease flares were notably more frequent in the placebo arm, consistent with the drug's therapeutic benefit. Injection-site reactions were infrequent and mild.

Serious adverse events were infrequent in the duvakitug arms, with the imbalance versus placebo driven largely by more Crohn's disease-related hospitalizations in the placebo group. No major safety signals including opportunistic infections, malignancies, or major adverse cardiovascular events were reported. The favorable safety profile is consistent with the selective mechanism: TL1A/DR3 signaling is primarily active in mucosal immune compartments, and its neutralization may not broadly suppress systemic immunity in the manner of TNF inhibitors or JAK inhibitors. Phase 3 trials are planned to enroll a larger patient population for both induction and maintenance, which will provide more comprehensive long-term safety data.

How Does Duvakitug Compare to Existing Crohn's Disease Treatments?

The current biologic landscape for Crohn's disease includes four major drug classes: TNF inhibitors (adalimumab, infliximab, certolizumab), the IL-12/23 inhibitor ustekinumab, IL-23 inhibitors (risankizumab, guselkumab, mirikizumab), and integrin antagonists (vedolizumab). JAK inhibitors (upadacitinib) represent a newer oral option. Despite this array of therapies, a significant proportion of patients experience primary non-response (30-40% for each class) or secondary loss of response over one to two years, highlighting the need for therapies with novel mechanisms of action.

For context, adalimumab achieved approximately 36% clinical remission at week 4 in the CLASSIC-I trial, ustekinumab achieved approximately 34% clinical remission at week 8 in the UNITI-1 trial, and risankizumab achieved approximately 45% clinical remission at week 12 in the ADVANCE trial — though these trials enrolled different patient populations and used different timepoints, making direct comparisons unreliable. For endoscopic outcomes, risankizumab has set a high bar with endoscopic remission rates of approximately 35% in Phase 3 induction. While Phase 2 results often attenuate in larger Phase 3 trials, the magnitude of duvakitug's effect and the clear dose-response suggest that the anti-TL1A mechanism provides meaningful clinical benefit. Additionally, TL1A's unique role in intestinal fibrosis raises the possibility that duvakitug may have anti-fibrotic properties not shared by existing biologics — a critical unmet need, as no approved therapy addresses fibrotic strictures in Crohn's disease. Duvakitug is one of several anti-TL1A antibodies in development, alongside tulisokibart (Merck) and afimkibart (Roche), reflecting broad industry conviction in this novel target class.