Safety and Efficacy of ABP-745 in Participants With an Acute Gout Flare

Key Inclusion Criteria:

Subjects are eligible for the study if they meet all of the following Inclusion Criteria:

• Age 18-70 years old (inclusive), male or female.

• Body mass index (BMI)18-40 kg/m2 (inclusive).

• Medical history and current findings consistent with diagnosis of gouty arthritis.

• Subjects must have experienced 2 or more gout flares within 12 months prior toscreening.

• Onset of an acute gout flare, within 6 months

• Patients receiving ULT agents (such as allopurinol, febuxostat, probenecid, etc.)must be on stable doses of these drugs prior to first dose of study drug (and remainon the same dose throughout the Treatment Period).

• Subjects agree to maintain a stable lifestyle (such as diet and exercise) during thestudy period.

Key Exclusion Criteria:

Subjects are excluded from the study if one or more of the following criteria are met:

• Administration of oral prednisone ≥ 10 mg or equivalent doses of otherglucocorticoids, or use of narcotics, within 24 hours prior to first dose of studydrug, or intramuscular, intravenous, or intra-articular injection of anyglucocorticoid within 14 days prior to first dose of study drug.

• Use of Nonsteroidal Anti-inflammatory Drugs (NSAIDs) prior to first dose dose ofstudy drug, at the investigator's discretion.

• Administration of colchicine or ABP-745 within 14 days prior to first dose of studydrug.

• Subjects took any investigational drug in any clinical study within 1 month prior tofirst dose of study drug and throughout the study period.

• Administration of pegloticase, or methotrexate, or any biologic IL-1 blocker, TNFinhibitor, or other biological agent within 30 days prior to first dose of studydrug or within 5 half-lives of the study drug prior to the first dose of study drug,whichever is longer.

• Administration of muscle relaxants, central stimulants, barbiturates, etc. within 30days prior to first dose of study drug or within 5 half-lives of the drug prior tothe first dose of study drug, whichever is longer.

• Secondary gout (e.g., gout induced by chemotherapy, transplant-related gout).

• Subjects with a current diagnosis or history of rheumatoid arthritis, psoriaticarthritis, evidence or suspicion of infectious/septic arthritis, calciumpyrophosphate (CPP) crystal arthritis, acute polyarticular gout (4 or more joints),multiple sclerosis or any other demyelinating disease, or; major chronicinflammatory disease or connective tissue disease other than RA or psoriaticarthritis (PsA), including but not limited to fibromyalgia or systemic lupuserythematosus (with the exception of secondary Sjögrens syndrome, etc.); witharthritis due to any cause other than gout that may confound any study assessmentsper Investigator discretion or Prosthetic joint infection within 5 years ofscreening, or native joint infection within 1 year of screening

• Current anticoagulation therapy, thrombocytopenia, or diseases with a risk ofthrombocytopenia, such as aplastic anemia, hypersplenism, or known hemorrhagicdiseases like idiopathic thrombocytopenic purpura or hemophilia.

• History of malignancy within 5 years prior to screening, excluding localized cancerssuch as basal cell carcinoma.

• Presence of significant diseases, including but not limited to: uncontrolledhypertension (systolic blood pressure ≥160 or diastolic blood pressure ≥100 mmHg),congestive heart failure (New York Heart Association [NYHA] class III or above),uncontrolled type 1 or 2 diabetes mellitus (hemoglobin A1c [HbA1c] >8.5%). Inclusionwill be determined by the Investigator based on the subject's specific condition.

• Women of childbearing potential as defined by Appendix 2.

• Experienced only no or mild gout-related pain prior to first dose of study drug.

• Use of gout flare prophylaxis (e.g., colchicine, NSAIDs,prednisone/methylprednisolone) at the time of randomization based on conversationwith subject and self-reported.

• Corona Virus Disease (COVID) vaccination in the 4 weeks prior to randomization.