Study to Evaluate the Urate-Lowering Activity and Safety of Oral BCX4208 Administered in Subjects With Gout

Inclusion Criteria:

1. Age ≥18 to <70 years
2. Have read and signed the ICF after the nature of the study has been fully explained
3. Screening sUA ≥8.0 mg/dL
4. Diagnosis of gout according to the preliminary criteria of the American Rheumatism Association (1977)

5. Female participants must meet at least one of the following specifications:

   • Be surgically sterile
   • Be post-menopausal as defined by:
   • females ≥55 years of age whose last menstrual period >1 year
   • females between ≥45 and <55 years of age whose last menstrual period > 1 year and FSH >40 mIU/mL and estradiol <40 pg/mL
   • Use oral contraceptives or some other form of hormonal birth control including hormonal vaginal rings or transdermal patches for 3 months prior to study drug dosing through 4 weeks after study drug administration
   • Use an intrauterine device as birth control for 8 weeks prior to study drug dosing through 4 weeks after study drug administration
   • Use (or ensure male partner[s]'s compliance with) a barrier contraception method (condom or diaphragm with a spermicide) for 4 weeks prior to study drug dosing through 4 weeks after study drug administration
6. Male participants must be considered not of child-bearing potential defined as >1 year post-vasectomy or use a condom for 4 weeks prior to study drug dosing through 4 weeks after study drug administration. In addition, they must ensure their sexual partner complies with the female contraception requirements specified above.
7. Be willing to avoid procreation for 3 months after study drug administration.
8. Be willing and able to provide authorization for the use and disclosure of personal health information in accordance with Health Insurance Portability and Accountability policy.

Exclusion Criteria:

1. Unstable angina
2. History of cardiac arrhythmia
3. History of congenital long QT
4. Presence of cardiac signs or symptoms compatible with New York Heart Association Class III or Class IV functional status for congestive heart failure or angina
5. Uncontrolled hypertension (above 150/95 mm Hg)
6. History of moderate or severe renal impairment and/or previous clinical laboratory data indicating an estimated calculated creatinine clearance < 60 mL/min during the previous 12 months
7. ALT/AST values >2.0 x ULN
8. CD4+ cell counts by flow cytometry <500 cells/mm3 or >1600 cells/mm3
9. Hemoglobin <12 g/dL or >17 g/dL (males) or < 11 g/dL or >16 g/dL (females)
10. Hematocrit <37% or >51% (males) or <33 % or >47% (females)
11. WBC <3.7 x 109/L or >11 X 109/L
12. Immunocompromised due to illness or organ transplant
13. Current use of systemic immunosuppressive medications or treatments
14. Gout flare during the Screening Period that is resolved for less than 3 weeks prior to first treatment with study drug (exclusive of chronic synovitis/ arthritis)
15. Recipient of any live, attenuated vaccine within 6 weeks of Screening
16. History of clinically significant and relevant drug and/or food allergies
17. History of chronic or recurrent infections
18. History of any type of cancer (hematologic or solid tumor), that has required chemotherapy or radiation therapy in the previous 12 months, excluding non-melanomatous localized skin cancer
19. Use of uric acid-lowering drugs within 30 days prior to the first dose of study drug or other prohibited medications within the timeframes specified in the protocol
20. ACTH administration within 30 days of first treatment with study drug
21. Intra-articular corticosteroid administration within 30 days of first treatment with study drug
22. Systemic or oral glucocorticosteroid use within 4 weeks of first treatment with study drug or for a period of ≥ 6 months out of the last 12 months prior to the first treatment with study drug
23. History of alcohol or drug abuse within the year prior to the signing of the ICF, or current evidence of substance dependence or abuse (alcohol intake > 3 drinks per day)
24. Female subjects who are pregnant, planning a pregnancy or breastfeeding
25. Positive pregnancy test
26. Positive serology for hepatitis B or C surface antigen or human immunodeficiency virus (HIV) type 1
27. Have been the recipient of any investigational drug within the last 30 days prior to the first treatment with study drug
28. Other medical conditions which, in the opinion of the Principal Investigator, would jeopardize the safety of the study subject or impact the validity of the study results