Multi-Dose Safety/Pharmacodynamic Study of SEL-212/SEL-037 in Subjects With Symptomatic Gout & Elevated Blood Uric Acid

This is an open label multicenter study to evaluate the safety and tolerability of multiple doses (3 monthly IV infusions) of SEL-212 ( a combination of pegsiticase (SEL-037) and SVP-rapamycin (SEL-110)) followed by multiple doses (2 monthly IV infusions) of pegsiticase (SEL-037) alone for a total of 5 treatment cycles in subjects with symptomatic gout and hyperuricemia. Additional participants will be treated with multiple doses ( 5 monthly IV infusions) of pegsiticase (SEL-037) alone.

Participants will be monitored for safety endpoints through the 5th treatment cycle plus 30 days .Pharmacokinetic samples will be drawn at pre-determined time points in addition to weekly serum uric acid levels.

This is an open label multicenter study to evaluate the safety and tolerability of multiple doses (3 monthly IV infusions) of SEL-212 ( a combination of pegsiticase ( SEL-037, also known as pegadricase) and SVP-rapamycin (SEL-110)) followed by multiple doses (2 monthly IV infusions) of pegsiticase (SEL-037) alone for a total of 5 treatment cycles in participants with symptomatic gout and hyperuricemia. Additional participants will be treated with multiple doses (5 monthly IV infusions) of pegsiticase (SEL-037) alone.

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. All participants will be monitored for safety and tolerability to drug throughout the study on a weekly schedule. Pharmacokinetic and pharmacodynamic parameters will at specific timepoints to monitor for continued efficacy. Pharmacodynamic parameters measured include uric acid levels and levels of ADAs.

The study duration per enrolled participant will be approximately 6 months including a 1 month screening period followed by 5 treatment cycles and an end of treatment visit which will occur 30 days after the last IV infusion .

Eligibility Criteria:
Inclusion Criteria:

1. Adult (age 21-75 inclusive) men and women of non child bearing potential with established or symptomatic gout which is defined as having at least ONE of any of the 3 following factors:

   1. ≥ 1 tophus
   2. 1 gout flare within the last 6 months
   3. Chronic gouty arthropathy
2. Screening serum uric acid of \>6 mg/dL
3. On a gout flare prophylactic regimen for 7 days prior to first dose
4. Willing to provide written informed consent prior to first study procedure is performed.
5. Understands and is willing and able to comply with study requirements, including the schedule of follow-up visits.

Exclusion Criteria:

1. History of anaphylaxis or severe allergic reaction.
2. History of an allergy to pegylated products.
3. Women of child bearing potential, Defined as:

   * \<6 weeks after surgical bilateral salpingooperhectony with or without hysterectomy
   * Pre or perimenopausal ( \< less than 24 months of natural amenorrhea)
4. Initiation or change in dose of hormone-replacement therapy for menopausal women less than 1 month prior to the Screening Visit or during the Screening Phase would be exclusionary. If after being on a stable dose of hormone-replacement therapy for one month the patient may be considered for the study if she continues to meet all other inclusion and exclusion criteria
5. Uncontrolled diabetes with baseline HbA1c ≥8%;
6. Glucose-6-phosphate dehydrogenase deficiency;
7. Uncontrolled hypertension
8. Ongoing treatment for arrhythmia, including placement of an implantable defibrillator;
9. History of coronary artery disease, including myocardial infarction;
10. Congestive heart failure, New York Heart Association Class III or IV;
11. ECG with evidence of prior myocardial infarction, clinically significant arrhythmia, or other abnormalities that, in the opinion of the investigator, are consistent with significant underlying cardiac disease;
12. History of hematological or autoimmune disorders, is immunosuppressed or immunocompromised;
13. Prior exposure to any experimental or marketed uricase (e.g., rasburicase (Elitek, Fasturtec), pegloticase (Krystexxa®), pegsiticase (SEL-037)
14. History of malignancy within the last 5 years other than basal skin cancer;
15. Subjects who, in the opinion of the investigator, present with a condition that would compromise their safety or that would make study completion unlikely.