Efficacy and Safety APT-1011 in Adult Subjects With Eosinophilic Esophagitis (EoE) (FLUTE-2)

Inclusion Criteria:

1. Male or female ≥18 years of age at the time of informed consent or assent
2. Each subject must read, understand, and provide consent on the ICF for this study andbe willing and able to adhere to study-related treatment regimens, procedures, andvisit schedule
3. Diagnosis or presumptive diagnosis of EoE that is confirmed during the Screeningperiod by histology that demonstrates ≥15 peak eos/HPF. In order to ensure that adiagnosis can be made, at least 6 biopsies should be taken including both proximal anddistal specimens (at least 3 each). Mid-esophageal biopsies are not required (optional). HPF will be defined as a standard area of 235 square microns in amicroscope with 40x lens (0.3 mm^2) and 22 mm ocular.
4. Esophagogastroduodenoscopies and biopsies are to be obtained during the Screeningperiod
5. Biopsies will be read by a central pathologist
6. Esophagogastroduodenoscopies and biopsies performed outside the study will not beaccepted to meet eligibility criteria
7. Optional biopsies may be taken and processed locally for local use, if specifiedin the local ICF. If serious pathology is unexpectedly encountered biopsies ofsuch lesions must be processed locally
8. Have a subject-reported history of ≥6 episodes of dysphagia in the 14 days prior tobaseline
9. Completion of the daily diary on at least 11 out of the 14 days during the 2-weekBaseline Symptom Assessment

Exclusion Criteria:

1. Have known contraindication, hypersensitivity, or intolerance to corticosteroids
2. Have a contraindication to, or factors that substantially increase the risk of, EGDprocedure or esophageal biopsy or have narrowing of the esophagus that precludes EGDwith a standard 9 mm endoscope
3. Have history of an esophageal stricture requiring dilatation within the 12 weeks priorto Screening
4. Have any physical, mental, or social condition or history of illness or laboratoryabnormality that in the Investigator's judgment might interfere with study proceduresor the ability of the subject to adhere to and complete the study or increase thesafety risk to the subject such as uncontrolled diabetes or hypertension
5. History or presence of oral or esophageal mucosal infection whilst using inhaled ornasal corticosteroids
6. Have any mouth or dental condition that prevents normal eating (excluding braces)
7. Have any condition affecting the esophageal mucosa or altering esophageal motilityother than EoE, including erosive esophagitis (grade B or higher as per the LosAngeles Classification of Gastroesophageal Reflux Disease; hiatus hernia longer than 3cm, Barrett's esophagus, and achalasia)
8. Use of systemic (oral or parenteral) corticosteroids within 60 days before Screening,use of swallowed corticosteroids within 30 days before Screening
9. Initiation of either inhaled or nasal corticosteroids or high-potency dermal topicalcorticosteroids within 30 days before Screening
10. Use of calcineurin inhibitors or purine analogues (azathioprine, 6-mercaptopurine) inthe 12 weeks before Screening
11. Use of potent cytochrome P450 (CYP) 3A4 inhibitors (eg, ritonavir and ketoconazole) inthe 12 weeks before Screening
12. Initiation of an elimination diet or elemental diet within 30 days before Screening (diet must remain stable after signing ICF)
13. Morning (07:00 to 09:00, or as close to that window as possible) serum cortisol level ≤5 μg/dL (138 nmol/L) that is not responsive to adrenocorticotropic hormone (ACTH)stimulation: defined as a serum cortisol level <16 μg/dL (440 nmol/L) at 60 minuteswith ACTH stimulation test using 250 μg cosyntropin (i.e., an abnormal result on theACTH stimulation test)
14. Use of biologic immunomodulators in the 24 weeks before Screening (allergydesensitization injection or oral therapy is allowed as long as the course of therapyis not altered during the study period)
15. Subjects who have initiated, discontinued, or changed dosage regimen of histamine H2receptor antagonists, antacids or antihistamines for any condition such asgastro-esophageal reflux disease within 4 weeks before qualifying endoscopy duringScreening. If already receiving these drugs, the dosage must remain constantthroughout the study
16. Subjects who have changed dosage regimen of PPIs within 8 weeks before qualifyingendoscopy. If already receiving PPIs, the dosage must remain constant throughout thestudy
17. Infection with hepatitis B, hepatitis C, or human immunodeficiency virus
18. Have gastrointestinal bleeding or documented active peptic ulcer within 4 weeks priorto Screening or entering a new study period
19. Have chronic infection such as prior or active tuberculosis, active chicken pox ormeasles or absence of prior measles, mumps and rubella vaccine. Subjects withtuberculosis exposure or who live in, or travel to, high endemic areas should beassessed locally for tuberculosis before consideration for the study
20. Immunosuppression or immunodeficiency disorder
21. Have a history or presence of Crohn's disease, celiac disease, or other inflammatorydisease of the gastrointestinal tract, including eosinophilic gastroenteritis
22. Have current drug abuse in the opinion of the Investigator.
23. Have current alcohol abuse in the opinion of the Investigator.
24. Female subjects who are pregnant, breastfeeding, or planning to become pregnant duringthe study
25. Sexually active females of childbearing potential who do not agree to follow highlyeffective contraceptive methods through the End of Study visit
26. Have received an investigational product, as part of a clinical trial within 30 days (or 5 half-lives, whichever is longest) of Screening. Subjects who are currentlyparticipating in observational studies or enrolled in patient registries are allowedin this study
27. Have participated in a prior study with investigational product APT-1011