Lesinurad and Febuxostat Combination Extension Study in Gout

This is a Phase 3 extension study to assess the long-term efficacy and safety of lesinurad in
combination with febuxostat in subjects who completed the double-blind treatment period in
Study RDEA594-304.

Inclusion Criteria:

- Subject is able to understand the study procedures and the risks involved and is
willing to provide written informed consent before the first study related activity.

- Subject completed the double-blind treatment period in Study RDEA594-304 and was
actively receiving and tolerating study medication (lesinurad or placebo) and
febuxostat 80 mg at the Month 12 visit.

- Subject is male or female; female subjects of childbearing potential must agree to use
an effective non-hormonal method of birth control during the study and for at least 14
days after the last dose of study medication.

Exclusion Criteria:

- Subject has any medical or psychological condition, which in the opinion of the
Investigator and/or the Medical Monitor, might create undue risk to the subject or
interfere with the subject's ability to comply with the protocol requirements, or to
complete the study.