An Extension Study of AK002 in Patients With Eosinophilic Gastritis and/or Eosinophilic Gastroenteritis

Inclusion Criteria:

1. Provide written informed consent.

2. Completed Study AK002-003, defined as having received 4 infusions of study drug and
followed through Day 113 (±3 days) in Study AK002-003 and willing to begin extended
dosing on or about Day 113.

3. Able and willing to comply with all study procedures.

4. 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.

5. 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.

Exclusion Criteria:

1. Poor tolerance to previous administration of AK002 in the opinion of the Investigator.

2. Known hypersensitivity to any constituent of the study drug.

3. Any disease, condition (medical or surgical), or cardiac abnormality, which, in the
opinion of the Investigator, would place the patient at increased risk.

4. Planned or expected vaccination with live attenuated vaccines during the treatment, or
vaccination expected within 5 half-lives (4 months) of AK002 administration.

5. Women who are pregnant, breastfeeding, or planning to become pregnant while
participating in the study.

6. Any other reason that, in the opinion of the Investigator or Medical Monitor, makes
the patient unsuitable for enrollment.