For business consideration, a new long-term safety study will be conducted in the next new pivotal studies.

The primary objectives of this study are to assess the safety, tolerability, and efficacy of ABP-671 in lowering serum uric acid (sUA) in participants with gout who roll over from Study ABP-671-301 after they complete the double-blind 28-week Treatment Period of Part 1 (Phase 2b) or Part 2 (Phase 3).

Inclusion Criteria:

• Must have completed the double-blind Treatment Period in Study ABP-671-301 (Part 1 or Part 2) and are actively receiving and tolerating the study drug up to the Week 28 visit in Study ABP-671-301

Exclusion Criteria:

• Has a new medical or psychological condition that, in the opinion of the Investigator and/or Medical Monitor, might create undue risk to the participant, interfere with the participant's ability to comply with the protocol requirements to complete the Extension Study, or potentially compromise the results or interpretation of the Extension Study.
• Is planning to become pregnant or breastfeed during the study or within ≤30 days after the last dose of the study drug.
• Is intolerant or unwilling to take colchicine or naproxen.