Inclusion Criteria:

• Adult male or female ≥ 12 years of age at the time of informed consent or assent.
• Each subject and/or their parents or legal guardian (for adolescents), must read, understand and provide consent or assent together with their parent(s) or guardian signature (for adolescents) on the ICF for this study and be willing and able to adhere to study-related treatment regimens, procedures and visit schedule.
• Diagnosis or presumptive diagnosis of EoE that is confirmed during the Screening period by histology that demonstrates ≥ 15 peak eos/HPF. In order to ensure that a diagnosis can be made, at least 6 biopsies should be taken from both proximal and distal 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 a microscope with 40x lens and 22mm ocular:
  • Esophagogastroduodenoscopies and biopsies are to be obtained during the Screening period;
  • Biopsies will be read by a central pathologist;
  • Esophagogastroduodenoscopies and biopsies performed outside the study will not be accepted to meet eligibility criteria;
  • Optional biopsies may be taken and processed locally for local use, only where specified in the local ICF. If serious pathology is unexpectedly encountered biopsies of such lesions must be processed locally.
• Have a subject-reported history of ≥ 6 episodes of dysphagia in the 14 days prior to baseline.
• Completion of the daily diary on at least 11 out of the 14 days during the 2-week Baseline Symptom Assessment.

Exclusion Criteria:

• Have known contraindication, hypersensitivity, or intolerance to corticosteroids.
• Have a contraindication to, or factors that substantially increase the risk of, EGD procedure or esophageal biopsy or have narrowing of the esophagus that precludes EGD with a standard 9 mm endoscope.
• Have history of an esophageal stricture requiring dilatation within the previous 12 weeks prior to Screening.
• Bone age more than 12 months behind chronological age for adolescent subjects.
• Have any physical, mental, or social condition or history of illness or laboratory abnormality that in the Investigator’s judgment might interfere with study procedures or the ability of the subject to adhere to and complete the study or increase the safety risk to the subject such as uncontrolled diabetes or hypertension or may increase risk of corticosteroid toxicity (e.g., abnormal bone mineral density).
• History of recurrent or current oral or esophageal mucosal infection due to inhaled or nasal corticosteroids.
• Have any mouth or dental condition that prevents normal eating.
• Have any condition affecting the esophageal mucosa or altering esophageal motility other than EoE, including erosive esophagitis (grade B or higher as per the Los Angeles Classification of Gastroesophageal Reflux Disease;21, hiatus hernia longer than 3 cm, Barrett’s esophagus, and achalasia.
• Use of systemic (oral or parenteral) corticosteroids within 60 days before Screening, use of swallowed corticosteroids within 30 days before Screening.
• Initiation of either inhaled or nasal corticosteroids or high-potency dermal topical corticosteroids within 30 days before Screening
• Use of calcineurin inhibitors or purine analogues (azathioprine, 6-mercaptopurine) in the 12 weeks before Screening.
• Use of potent cytochrome P450 (CYP) 3A4 inhibitors (eg, ritonavir and ketoconazole) in the 12 weeks before Screening.
• Initiation of an elimination diet or elemental diet within 30 days before Screening (diet must remain stable after signing ICF).
• 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 ACTH stimulation: defined as a serum cortisol level < 16 μg/dL (440 nmol/L) at 60 minutes with ACTH stimulation test using 250 μg cosyntropin administered intramuscularly (i.e., an abnormal result on the ACTH stimulation test).
• Use of biologic immunomodulators in the 24 weeks before Screening (allergy desensitization injection or oral therapy is allowed as long as the course of therapy is not altered during the study period).
• Subjects who have initiated, discontinued, or changed dosage regimen of histamine H2 receptor antagonists, antacids or antihistamines, leukotriene inhibitors or sodium cromolyn within 4 weeks before qualifying endoscopy. If already receiving these drugs, the dosage must remain constant throughout the study.
• Subjects who have changed dosage regimen of PPIs within 8 weeks before qualifying endoscopy. If already receiving PPIs, the dosage must remain constant throughout the study.
• Infection with hepatitis B, hepatitis C, or human immunodeficiency virus.
• Have gastrointestinal bleeding or documented active peptic ulcer within 4 weeks prior to Screening or entering a new study period.
• Have chronic infection such as prior or active tuberculosis, active chicken pox or measles or absence of prior measles, mumps and rubella vaccine. Subjects with tuberculosis exposure or who live in high endemic areas should be assessed locally for tuberculosis before consideration for the study.
• Immunosuppression or immunodeficiency disorder.
• Current malignancy or malignancy within 3 years of Screening. Subjects in remission for at least 3 years post-treatment may be enrolled.
• Known severe bleeding disorder.
• Have a history or presence of Crohn’s disease, celiac disease, or other inflammatory disease of the gastrointestinal tract, including eosinophilic gastroenteritis.
• Have current drug abuse in the opinion of the Investigator.
• Have current alcohol abuse in the opinion of the Investigator.
• Female subjects who are pregnant, breastfeeding, or planning to become pregnant during the study.
• Sexually active females of childbearing potential who do not agree to follow highly effective contraceptive methods through the End of Study visit.
• Have received an investigational product, as part of a clinical trial within 30 days (or 5 halflives, whichever is longest) of Screening. Subjects who are currently participating in observational studies or enrolled in patient registries are allowed in this study.
• Have participated in a prior study with investigational product APT-1011.