Parent study closed to enrollment

This STRING study will examine markers of esophageal inflammation using a minimally-invasive testing device, the esophageal string test (EST). The primary objective is to determine the effect of omalizumab (Xolair) and dupilumab (Dupixent) on markers of eosinophilic inflammation in the esophagus of subjects treated with omalizumab-facilitated mOIT(mult-allergen oral immunotherapy) and/or mOIT with concurrent dupilumab.

This is a companion study to a phase 2 randomized, controlled, double-blind clinical trial using biologics to improve multi-allergen oral immunotherapy (mOIT) outcomes. The parent study (COMBINE NCT03679676) consists of a screening period, 8 weeks of omalizumab or placebo injections, and 24 weeks of OIT with dupilumab or placebo injections followed by an off-treatment period.

This STRING companion study will examine markers of esophageal inflammation during the COMBINE study using a minimally-invasive testing device, the esophageal string test (EST). If participants of COMBINE consent to this companion study, they will undergo an esophageal string test at the following time points in COMBINE:

• During screening, prior to week 0, which will be baseline for the STRING esophageal test
• Week 8, After the 8 weeks of treatment with omalizumab/placebo
• If dose-related gastrointestinal (GI) side effects occur during the week 10-32 treatment period (OIT and dupilumab/placebo)
• At Week 32, after 24 weeks of treatment with OIT and dupilumab or placebo

Inclusion Criteria: • Participants, aged 5-55 years enrolled in the parent COMBINE trial

• Able to swallow the EST.

Exclusion Criteria: • Allergy to, or inability to ingest, gelatin

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