Safety and Dose Ranging Study of Insulin Receptor MoAb-IDS Fusion Protein in Patients With Hunter Syndrome

This is a sequential, open-label, dose escalation, multi-dose study in adults with Hunter
syndrome. Two dose levels, assuming tolerability, are planned sequentially, with safety data
from the previous cohort being reviewed prior to escalation to the next higher dose cohort.
Subjects will receive weekly doses of AGT-182 for 8 weeks if ERT-naive or agreeing to a
6-week ERT washout, or for 13 weeks if currently taking ERT and not agreeing to washout.

Inclusion Criteria:

- Male age 18 years or older

- Diagnosis of Hunter Syndrome (documented fibroblast or leukocyte IDS enzyme activity
level of less than 10% of the lower limit of the normal range of the measuring
laboratory - or any level of enzyme deficiency together with the presence of a
pathogenic mutation in the IDS gene - and documentation of normal enzymatic activity
of at least 1 other sulfatase.)

- Must fall into one of the following groups:

- currently receiving standard enzyme replacement therapy (ERT) and be willing to
discontinue it for the study duration, taking AGT-182 instead

- have not received standard ERT for at least 3 months and have elevated uGAGs of
at least 3.5 fold above age-related normals at study screening

- have never received ERT

- Voluntary written consent

- Sexually mature males must be advised to use a medically accepted method of
contraception throughout the study.

Exclusion Criteria:

- Refusal to complete screening/baseline evaluations

- Receipt of an investigational drug within the prior 90 days

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

- Clinically significant spinal cord compression, evidence of cervical instability

- Known hypersensitivity to idursulfase or any of the components of AGT-182

- Known to be nonresponsive to standard ERT treatment (i.e., high uGAG values despite
taking full dose standard ERT)

- History of diabetes mellitus or hypoglycemia

- Contraindication to lumbar puncture, if the patient agrees to this optional assessment