Safety and Dose Ranging Study of Insulin Receptor MAb-IDUA Fusion Protein in Patients With MPS I

Inclusion Criteria:

- Male age 18 years or older

- Diagnosis of MPS I (documented fibroblast or leukocyte IDUA enzyme activity level of
less than 10% of the lower limit of the normal range of the measuring laboratory)

- Voluntary written consent by patient or legally responsible representative

- All women of childbearing potential and sexually mature males must be advised to use
a medically accepted method of contraception throughout the study.

- Negative pregnancy test (females)

- Must not have received ERT for at least 6 weeks prior to AGT-181 treatment

- Must have elevated urinary GAGs if no ERT has been received in the prior 3 months

Exclusion Criteria:

- Refusal to complete baseline evaluations.

- Any medical condition or other circumstances that may significantly interfere with
study compliance

- Receipt of an investigational drug within the prior 90 days

- History of diabetes mellitus or hypoglycemia

- Clinically significant spinal cord compression, evidence of cervical instability.

- Known hypersensitivity to alpha-L-iduronidase or any of the components of AGT-181.

- Known to be nonresponsive to standard ERT treatment.

- Previously successful (engrafted) hematopoietic stem cell transplantation that
resulted in normalization of urinary GAGs.

- Contraindication for lumbar puncture