An Extension Study of Lirentelimab in Eosinophilic Gastritis and/or Eosinophilic Duodenitis (Formerly Referred to as Eosinophilic Gastroenteritis)

Study Overview
=================
Brief Summary
-----------------
This is a Phase 3, open-label, extension study to assess the long term efficacy and safety of lirentelimab given monthly.

Official Title
-----------------
A Phase 3, Multicenter, Open-Label, Extension Study to Evaluate the Efficacy and Safety of AK002 in Patients That Were Previously Enrolled in AK002-016 or AK002-012 Studies and Have Eosinophilic Gastritis and/or Eosinophilic Duodenitis (Formerly Referred to as Eosinophilic Gastroenteritis)

Conditions
-----------------
Eosinophilic Gastritis, Eosinophilic Duodenitis

Intervention / Treatment
-----------------
* Drug: lirentelimab


Participation Criteria
=================
Eligibility Criteria
-----------------
Key Inclusion Criteria: Provide written informed consent. Completed Study AK002-016, defined as having received 6 infusions of study drug and followed through Day 176 (±3) or completed Study AK002-012, defined as having received the cohort-appropriate amount of doses and followed for 5 months after last dose of study drug. If patient is on pre-existing dietary restrictions, willingness to maintain those restrictions, throughout the study. Able and willing to comply with all study procedures. Female patients must be either post-menopausal for at least 1 year or surgically sterile (tubal ligation, hysterectomy, or bilateral oophorectomy) for at least 3 months, or if of childbearing potential, have a negative pregnancy test and agree to use dual methods of contraception, or abstain from sexual activity until the end of the study, or for 120 days following the last dose of study drug, whichever is longer. Male patients with female partners of childbearing potential must agree to use a highly effective method of contraception until the end of the study or for 120 days following the last dose of study drug, whichever is longer. All fertile men with female partners of childbearing potential should be instructed to contact the Investigator immediately if they suspect their partner might be pregnant at any time during study participation. Key Exclusion Criteria: Known hypersensitivity to any constituent of the study drug. Any disease, condition (medical or surgical), or cardiac abnormality, which, in the opinion of the Investigator, would place the patient at increased risk. Planned or expected vaccination with live attenuated vaccines during the Treatment Period, or vaccination expected within 5 half-lives (4 months) of AK002 administration. Women who are pregnant, breastfeeding, or planning to become pregnant while participating in the study. Any other reason that, in the opinion of the Investigator or Medical Monitor, makes the patient unsuitable for enrollment.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 3.0 mg/kg of Lirentelimab (AK002)<br>Subjects in this arm will receive up to 18 monthly doses (3mg/kg) of lirentelimab (AK002) | Drug: lirentelimab<br>* Lirentelimab (AK002) is a humanized non-fucosylated immunoglobulin G1 (IgG1) monoclonal antibody directed against Siglec-8<br>* Other names: AK002;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The safety and tolerability of lirentelimab by evaluating adverse events assessed using the CTCAE version 5.0 |  | Day 561 (End of Study) | 
| The safety and tolerability of lirentelimab as assessed by symptom-directed physical examination of reported or observed patient symptoms warranting examination, including assessments of possible infusion site reactions and infusion-related reactions |  | Day 1 to Day 561 (End of Study) | 
| Evaluation of symptoms of EG and/or EGE using a daily disease-specific patient questionnaire (PRO Questionnaire) |  | Basline to Day 561 (End of Study) | 
| Changes in the number of eosinophils in gastric and/or duodenal mucosa |  | Baseline to Day 505 |