Phase 2b/3 Study to Assess ABP-671 a Novel URAT1 Inhibitor in Participants With Gout

Inclusion Criteria:

• Male and female participants aged ≥19 and <70 years of age at the time of informedconsent.

• A body mass index (BMI) of ≥18 kg/m2 to ≤40 kg/m2.

• Diagnosis of gout per American College of Rheumatology/European Alliance ofAssociations for Rheumatology 2015 Gout Classification Criteria and must meet thecriteria as follows:

• At Screening, participants with gout on ULT (including allopurinol) must bewilling to discontinue ULT.

• At Screening, participants with gout who are not currently treated with any UAlowering therapy must have an sUA ≥7.5 mg/dL (≥0.450 mmol/L).

• At the confirmatory sUA visit, all participants must have an sUA ≥7.0 mg/dL (≥0.420mmol/L).

• Women of childbearing potential (WOCBP) must be surgically sterile (eg,hysterectomy, bilateral salpingectomy, or bilateral oophorectomy) or willing to useacceptable and highly effective double contraception from Screening until at least 30 days after the last dose of the study drug. Double contraception is defined as acondom AND one other form of the following:

• Established hormonal contraception (with approved oral contraceptive pills,long-acting implantable hormones, injectable hormones);

• A vaginal ring or an intrauterine device OR

• Documented evidence of surgical sterilization at least 6 months prior toScreening (eg, tubal occlusion, hysterectomy, bilateral salpingectomy, orbilateral oophorectomy for women or vasectomy for men [with appropriatepost-vasectomy documentation of the absence of sperm in semen] provided themale partner is the sole partner). The absence of records will not excludescreening the participant; if medical records cannot be obtained, serumpregnancy testing will be conducted to confirm the participant is not pregnant.

Note: Women not of childbearing potential must be postmenopausal for ≥12 months. Postmenopausal status will be confirmed through follicle stimulating hormone (FSH) concentration testing.

-Men must be surgically sterile (>30 days since vasectomy), abstinent, or if engaged in sexual relations with a female partner of childbearing potential, the participant must use an acceptable form of contraception from Screening until at least 30 days after the last dose of the study drug. Acceptable methods of contraception include the use of condoms in addition to the use of an effective contraceptive for the female partner that includes approved oral contraceptive pills, long-acting implantable hormones, injectable hormones, a vaginal ring, or an intrauterine device. Participants who practice abstinence (abstinence from penile-vaginal intercourse) are eligible when this is in line with their preferred and usual lifestyle. In addition, men must not donate sperm for at least 30 days after the last dose of the study drug.

Exclusion Criteria:

• History of rheumatoid arthritis or other autoimmune disease.

• Clinically significant hepatic, cardiovascular, renal, neoplastic, psychiatric, orhematological disorders such as polycythemia vera, sickle cell disease, ormyelodysplastic disorder.

• Positive test result for HIV, hepatitis B surface antigen, or hepatitis C virusantibody. Active hepatitis C virus infection is defined as a participant with apositive hepatitis C antibody and detectable hepatitis C viral load RNA.

• Participants who, in the opinion of the Investigator, have a high genetic risk ofallopurinol hypersensitivity syndrome unless they have been found to be negative forHuman leukocyte antigen (HLA)-B*5801, either clinically by prior exposure toallopurinol or by laboratory evaluation.

• Liver function tests >2x the laboratory upper limit of normal (ULN) range ofaspartate aminotransferase, alkaline phosphatase, or alanine aminotransferase; totalbilirubin >1.5x ULN at Screening.

• Inadequate renal function with serum creatinine >1.5 mg/dL (>0.133 mmol/L) orestimated glomerular filtration rate (eGFR) < 60 mL/min/m2 (by the 2021 ChronicKidney Disease Epidemiology Collaboration creatinine-based eGFR equation).

• History of malignancy within the previous 5 years; with the exception ofnon-melanoma skin cancer that has been treated with no evidence of recurrence,treated cervical dysplasia, or treated in situ grade 1 cervical cancer.

• History within the last 12 months of unstable angina, New York Heart Associationfunctional class III or IV heart failure, myocardial infarction, stroke, venousthromboembolism, or a history of percutaneous coronary intervention.

• Uncontrolled hypertension (systolic BP ≥160 mmHg and/or diastolic BP ≥90 mmHg). IfBP is controlled while taking antihypertensive medication, the participant must beon stable dose for previous 2 months.

• Active liver disease or impaired hepatic function as assessed by liver functiontests.

• Received any investigational therapy within 30 days or 5 half-lives (whichever islonger) prior to Screening.

• Any other medical or psychological condition, that, in the opinion of theInvestigator and/or Medical Monitor, might create undue risk to the participant,interfere with the participant's ability to comply with the protocol requirements tocomplete the study, or potentially compromise the results or interpretation of thestudy.

• Pregnant, breastfeeding, or planning a pregnancy during the study or ≤30 days afterthe last dose of the study drug.

• Intolerant or unwilling to take colchicine or naproxen.