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

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.