A Study to Evaluate the Efficacy and Safety of CC-93538 in Adult and Adolescent Participants With Eosinophilic Esophagitis

Inclusion Criteria:

Participants must satisfy the following criteria to be enrolled in the study:

1. Male or female patients aged ≥ 12 and ≤ 75 years, with a body weight of > 40 kg.

2. Histologic evidence of eosinophilic esophagitis, defined as a peak count of ≥ 15eosinophils/high-power field at 2 levels of the esophagus.

3 Participant-reported history of 4 or more Dysphagia Days within 2 consecutive weeks prior to end of screening.

4. Lack of complete response to an adequate trial of proton pump inhibitor (8 weeks).Participants on a proton pump inhibitor must have been on a stable dose for at least 4 weeks prior to first Screening Visit and agree to continue the same dosethroughout the study.

5. Participants currently receiving inhaled corticosteroids, leukotriene receptorantagonists, or mast cell stabilizers for indications other than EoE, or mediumpotency topical corticosteroids for dermatologic conditions, must maintain stabledoses for at least 4 weeks prior to the first Screening Visit and throughout theduration of the study.

6. Participants must agree to maintain a stable diet (including any food eliminationdiet for the treatment of food allergy or eosinophilic esophagitis) and notintroduce any changes in their diet from the first Screening Visit to the end of thestudy.

7. Females of childbearing potential must have 2 negative pregnancy tests as verifiedby the Investigator prior to starting study therapy and agree to practice a highlyeffective method of contraception until 5 months after the last dose.

Exclusion Criteria:

The presence of any of the following will exclude a participant from enrollment:

1. Clinical or endoscopic evidence of other diseases that may affect the histologic,endoscopic, and clinical symptom evaluation for this study.

2. Other gastrointestinal disorders such as active Helicobacter pylori infection,esophageal varices, gastritis, colitis, celiac disease, Mendelian disorderassociated with eosinophilic esophagitis, liver function impairment, or a knownhereditary fructose intolerance.

3. Evidence of a severe endoscopic structural abnormality in the esophagus.

4. Esophageal dilation for symptom relief within 8 weeks prior to first Screening Visitor during the Screening Period, or if esophageal dilation is anticipated within 48weeks of dosing during the study.

5. Evidence of immunosuppression, or of having received systemic immunosuppressive orimmunomodulating drugs within 5 drug half-lives prior to the first Screening Visit.

6. Treatment with a high potency topical corticosteroid for dermatologic use, or asystemic corticosteroid within 8 weeks of the first Screening Visit.

7. Treatment with a swallowed topical corticosteroid, leukotriene receptor antagonist,or mast cell stabilizer for EoE, within 4 weeks of the first Screening Visit.

8. Treatment with oral or sublingual immunotherapy within 6 months of the firstScreening Visit (any use will be prohibited during the study). Subcutaneousimmunotherapy may be allowed if on stable doses for at least 3 months prior to thefirst Screening Visit and during the study.

9. Actively successful dietary modification adherence (e.g. food elimination diet),resulting in a complete response to EoE.

10. Prior treatment with CC-93538 during a Phase 1 or 2 clinical study.

11. Receipt of a live attenuated vaccine within 4 weeks of the first Screening Visit.

12. Any disease that would affect the conduct of the protocol or interpretation of thestudy results, or would put a patient at risk by participating in the study (e.g.severe uncontrolled asthma, infection causing eosinophilia, hypereosinophilicsyndrome, or cardiovascular condition, or neurologic disorder or psychiatric illnessthat compromises the Participant's ability to accurately document symptoms ofeosinophilic esophagitis).

13. Active or ongoing infections including parasitic/helminthic, hepatitis,tuberculosis, or human immunodeficiency virus.

14. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection within 4weeks of the first Screening Visit.

15. Females who are pregnant or lactating.