Safety and Pharmacodynamics of SEL-037 (Pegsiticase) in Subjects With Elevated Blood Uric Acid Levels

This Study will evaluate the safety, pharmacokinetics, pharmacodynamics and immunogenicity
of a single intravenous infusion of SEL-037 (pegsiticase), a pegylated uricase, in subjects
with elevated blood uric acid levels. Uricase is an enzyme that converts uric acid to the
readily soluble allantoin that is then excreted. Cohorts of Subjects will be given a single,
ascending dose intravenous infusion of SEL-037 and then monitored for safety, uric acid
levels and anti-drug-antibodies (ADAs) to SEL-037 for 30 days.

Inclusion Criteria:

- Male or female subjects ages 21 to 75 inclusive. Female subjects must be of
non-childbearing potential;

- Has at the Screening Visit a serum uric acid ≥ 6 mg/dL, with or without a history of
gout;

- The use of allopurinol, febuxostat (Uloric®), or probenecid as uric acid-lowering
therapy is permissible if dosing has been stable for at least the month prior to the
Screening Visit

- Has adequate venous access and able to receive IV therapy;

- Evidence of a personally signed and dated informed consent document indicating that
subject has been informed of all pertinent aspects of the study;

Exclusion Criteria:

- Prior exposure to any experimental or marketed uricase;

- History of any allergy to pegylated products,

- Glucose-6-phosphate dehydrogenase deficiency or known catalase deficiency;

- History of hematological or autoimmune disorders, is immunosuppressed or
immunocompromised;

- Has participated in a clinical trial within 30 days of the Screening;