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

Key Inclusion Criteria:

1. Provide written informed consent.
2. Completed Study AK002-016, defined as having received 6 infusions of study drug andfollowed through Day 176 (±3) or completed Study AK002-012, defined as having receivedthe cohort-appropriate amount of doses and followed for 5 months after last dose ofstudy drug.
3. If patient is on pre-existing dietary restrictions, willingness to maintain thoserestrictions, throughout the study.
4. Able and willing to comply with all study procedures.
5. Female patients must be either post-menopausal for at least 1 year or surgicallysterile (tubal ligation, hysterectomy, or bilateral oophorectomy) for at least 3months, or if of childbearing potential, have a negative pregnancy test and agree touse dual methods of contraception, or abstain from sexual activity until the end ofthe study, or for 120 days following the last dose of study drug, whichever is longer.
6. Male patients with female partners of childbearing potential must agree to use ahighly effective method of contraception until the end of the study or for 120 daysfollowing the last dose of study drug, whichever is longer. All fertile men withfemale partners of childbearing potential should be instructed to contact theInvestigator immediately if they suspect their partner might be pregnant at any timeduring study participation.

Key Exclusion Criteria:

1. Known hypersensitivity to any constituent of the study drug.
2. Any disease, condition (medical or surgical), or cardiac abnormality, which, in theopinion of the Investigator, would place the patient at increased risk.
3. Planned or expected vaccination with live attenuated vaccines during the TreatmentPeriod, or vaccination expected within 5 half-lives (4 months) of AK002administration.
4. Women who are pregnant, breastfeeding, or planning to become pregnant whileparticipating in the study.
5. Any other reason that, in the opinion of the Investigator or Medical Monitor, makesthe patient unsuitable for enrollment.