Safety and Pharmacodynamics of SEL-212 (Pegsiticase + SEL-110) in Subjects With Elevated Blood Uric Acid Levels

This Study will first evaluate the safety and pharmacokinetics of a single intravenous dose
of SEL-110, a nanoparticle containing rapamycin, in subjects with elevated blood uric acid
levels. This will be followed, in separate subjects, by evaluation of the safety,
pharmacokinetics, pharmacodynamics and immunogenicity of a single intravenous dose of
SEL-212, SEL-037 (pegsiticase) plus SEL-110, 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 and SEL-110 is designed to prevent unwanted anti-drug-antibodies (ADAs)
from forming. Cohorts of subjects in the SEL-110 only arms of the study will be given a
single, ascending intravenous dose of SEL-110 and then monitored for safety and rapamycin
levels (pharmacokinetics) over 30 days. Cohorts of subjects in the SEL-212 arms of the study
will be given a single, ascending intravenous dose of SEL-110 with a fixed dose of SEL-037
and then monitored for safety, rapamycin levels, SEL-037 levels, uric acid levels and
anti-drug-antibodies (ADAs) to SEL-037 for 30 days. One additional control group with
receive a single intravenous infusion of SEL-037 at a fixed dose and then monitored for
safety, SEL-037 levels, uric acid levels and anti-drug-antibodies (ADAs) to SEL-037 for 30
days

Inclusion Criteria:

- Male or female subjects ages 21 to 70 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 (for arms receiving SEL-037 or
SEL-212);

- 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;

- Presently taking a drug classified as CYP3A4 inducer or inhibitor;

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