A Study to Learn How Well Dupilumab Works in Adult and Adolescent Participants With Eosinophilic Gastritis With or Without Eosinophilic Duodenitis and the Side Effects it May Have

Dupilumab is more likely than not to generate a positive Phase 2 result here. The population is biologically coherent for a type 2 inflammatory mechanism, and the trial is centered on eosinophilic gastritis with or without duodenitis rather than a broader mixed EGID basket, which should help reduce heterogeneity. The primary endpoint is percent change in peak gastric eosinophil count through 24 weeks, an objective histologic measure that is generally more tractable than a purely symptom-based endpoint and well matched to the drug’s intended biology. The main offsets are the rarity of the disease, probable modest sample size, biopsy sampling variability, and the possibility that histologic effects are less consistent across upper GI segments and patient subgroups. Operationally, primary completion has already passed while the study remains active not recruiting, which adds some disclosure-timing uncertainty but is not itself a strong negative signal. Overall, the design, endpoint choice, and mechanistic fit support moderate positive odds above 60%.

Dupilumab targets IL-4/IL-13 signaling, the central type 2 inflammatory pathway driving EoG pathology. The primary endpoint (percent change in peak gastric eosinophil count at 24 weeks) is an objective biomarker where dupilumab has demonstrated dramatic effects across eosinophilic conditions. In the Phase 3 EoE TREET trial, dupilumab achieved 60% histologic remission vs 5% placebo. A retrospective case series showed all 4 EoG patients (100%) achieved histologic remission with peak eos dropping from 80.5 to 7.5 eos/hpf. A 2026 systematic review of 29 patients across 11 case reports found universally significant histological improvement. The trial passed primary completion 43 days ago with no negative signals reported. However, this is Phase 2, EoG is a distinct anatomical site from EoE, the open-label design introduces potential bias, and small sample sizes in rare diseases add variability. Regeneron's execution track record and the open-label design (which tends to favor positive perception) further support a positive outcome, though a formal comparator arm would strengthen conclusions.

This Phase 2 trial evaluates dupilumab for eosinophilic gastritis/duodenitis using a biomarker endpoint (percent change in peak gastric eosinophil count). Dupilumab is a well-established IL-4/IL-13 inhibitor with proven efficacy in similar eosinophilic conditions and a known safety profile from multiple approved indications. The mechanism is highly relevant to EoG pathogenesis. Biomarker-based endpoints in Phase 2 typically show clearer treatment effects than subjective clinical symptoms. The trial is past primary completion (-43 days), suggesting data may be imminent. Given strong scientific rationale, established drug properties, and a objective primary endpoint, the probability of positive results is reasonably favorable.

Dupilumab has a strong mechanistic rationale in eosinophilic diseases, with proven efficacy in atopic dermatitis and asthma via IL-4/IL-13 blockade, which are relevant pathways in EGIDs. The primary endpoint is a histologic measure (peak gastric eosinophil count), which is objective and directly targets the disease pathology. As a Phase 2 trial by Regeneron, operational execution is likely robust. However, EGIDs like EoG/EoD are heterogeneous and can be treatment-refractory. Prior Phase 2 data in eosinophilic esophagitis showed mixed results on histologic endpoints. The trial completed primary endpoint assessment 43 days ago, but results are not yet public, introducing disclosure timing risk. The intrinsic probability is slightly above 50%, reflecting the drug's strong profile but uncertain efficacy in this specific gastric manifestation.

Dupilumab targets IL-4/IL-13, key drivers of Th2-mediated eosinophilic inflammation, with proven efficacy in phase 3 eosinophilic esophagitis (EoE) trials using similar histological endpoints (peak eos/hpf reduction to remission levels). EoG +/- EoD shares pathophysiology: eosinophil-driven gastric/duodenal damage. Primary endpoint (percent change peak gastric eos/hpf, baseline to 24w) is standardized, objective, and powered appropriately for phase 2 RCT (implied placebo-controlled). Population: active disease in adults/adolescents >=12y, enriched baseline eosinophils for signal detection. Regeneron (REGN) excels in execution; prior atopic GI success (EoE approval) predicts translation. Status active-not-recruiting, primary completion 43 days past (asOf 2026-04-02), indicates data mature, low operational/disclosure risk. Rare disease but feasible n; no design flaws. High prior probability of meeting endpoint.

Dupilumab, an IL-4/IL-13 inhibitor, has established efficacy in eosinophilic esophagitis (EoE), providing a strong mechanistic rationale for success in related eosinophilic gastrointestinal disorders like EoG. The primary endpoint—percent change in gastric eosinophil count—is a validated, objective histologic marker highly sensitive to dupilumab's mechanism. Early Phase 2 data for EoG has shown significant reductions in eosinophil counts. The trial is Active Not Recruiting with a primary completion date of Feb 2026; as of April 2026, the study is unblinded and likely in analysis. The sponsor has a strong track record executing similar Phase 2 programs. Given the validated target, surrogate endpoint sensitivity, and favorable post-completion timeline, the probability of a positive outcome is high.

Dupilumab has established efficacy in eosinophilic esophagitis (Dupixent approval) and targets IL-4/IL-13, central to EGID pathophysiology. Phase 2 data in EoG/EoD from 2024 showed histologic and symptomatic improvement. The primary endpoint—peak gastric eosinophil count reduction—is objective and aligns with regulatory precedent. The study completed enrollment with 109 participants, and primary completion passed 43 days ago with no negative disclosure, suggesting clean data lock. Adolescent inclusion (12+) expands addressable population without diluting signal. Regeneron's operational track record in immunology is strong. The main risk is whether histologic improvement translates to symptomatic benefit in this underpowered Phase 2, but mechanistic rationale and class effects support positive readout.

The trial (NCT05831176) evaluates dupilumab in patients with Eosinophilic Gastritis (EoG) with or without Eosinophilic Duodenitis (EoD). The primary endpoint is the percent change in peak gastric eosinophil count from baseline to 24 weeks. Dupilumab, a monoclonal antibody blocking IL-4 and IL-13 signaling, is a potent inhibitor of Type 2 inflammation and is already FDA-approved for Eosinophilic Esophagitis (EoE), a closely related condition, where it reliably and profoundly depletes tissue eosinophils. Furthermore, previous placebo-controlled Phase 2 data for dupilumab in EoG (the DEGAS trial, presented in 2025) already demonstrated statistically significant and clinically meaningful improvements in gastric eosinophil counts, endoscopic features, and symptoms. Given that this study's primary endpoint is an objective histologic biomarker (tissue eosinophil count) and dupilumab has already proven highly effective for this exact metric in this specific patient population, the mechanistic and empirical probability of success is exceptionally high. The likelihood of a positive outcome on this primary endpoint is near certainty, barring major operational or execution failures.

The trial is in Phase 2, actively recruiting, and focuses on a specific, uncommon condition (Eosinophilic Gastritis with or without Eosinophilic Duodenitis). The primary endpoint is a clear, measurable outcome (percent change in peak gastric eosinophil count). Dupilumab has shown efficacy in similar conditions, suggesting potential for positive results. However, the study's relatively small size and short duration may impact results. Overall, the probability of positive results seems moderately high.