Background Three randomized, double-blind, Phase III trials reported that greater proportions of patients treated with lesinurad 200 mg (LESU200) or 400 mg (LESU400), combined with the xanthine oxidase inhibitor (XOI) allopurinol (ALLO; CLEAR 1 and 2) or febuxostat (FBX; CRYSTAL), achieved serum uric acid (sUA) targets at 6 months versus xanthine oxidase inhibitor (XOI) + placebo (PBO).
Objectives To evaluate the impact of long-term treatment with lesinurad + XOI on tophus and flares for at least 1 year and up to 2 years.
Methods Patients completing 12 months in the core CLEAR and CRYSTAL studies could enroll in respective uncontrolled, open-label extension studies (NCT01808131; NCT01808144). Patients randomized to LESU200 + XOI or LESU400 + XOI in the core studies who continued on combination therapy in the extension studies were analyzed. Efficacy endpoints included: (1) proportions of patients with complete resolution (CR) of ≥1 target tophus (i.e. measurable tophus on hands/wrists and/or feet/ankles 5–20 mm in longest diameter), (2) percent reductions in the total area of all target tophi, and (3) proportions of patients experiencing gout flares requiring treatment (GFRT).
Results A total of 239 (LESU200+ALLO) and 232 (LESU400+ALLO) patients continued in the CLEAR extension; 64 (LESU200+FBX) and 65 (LESU400+FBX) patients continued in the CRYSTAL extension. Proportions of patients with CR of ≥1 target tophus increased from end of core study (1 year) to 2 years: from 25.0% to 43.8% in LESU200+ALLO and 30.3% to 36.4% in LESU400+ALLO, and from 26.6% to 53.1% in LESU200+FBX and 35.4% to 58.5% in LESU400+FBX (LOCF). Percent reduction in the total area of all target tophi versus baseline changed from end of core study to 2 years: from 11.6% to 41.8% in LESU200+ALLO and 42.7% to 49.3% in LESU400+ALLO, and from 54.8% to 68.3% in LESU200+FBX and 58.6% to 72.4% in LESU400+FBX (LOCF). Proportions of subjects with a GFRT per month decreased during continued combination treatment in both extension studies (Figure). The proportions of patients with a GFRT during Months 1, 12, and 24 were, respectively, 16.3, 7.9, and 5.6 in LESU200+ALLO; 18.1, 6.9, and 3.0 in LESU400+ALLO; 26.6, 10.9, 6.3 in LESU200+FBX; and 36.9, 4.6, 1.9 in LESU400+FBX. Extended treatment with LESU + XOI did not result in increased exposure-adjusted incidence rates of adverse events (AEs), AEs leading to discontinuation of lesinurad, serious AEs, or clinical laboratory abnormalities.
Conclusions The CLEAR and CRYSTAL extension studies showed that patients treated with lesinurad + XOI for up to 2 years exhibited continued increases in the rate of complete resolution of tophi and reduction in tophus area, as well as decreased rates of GFRT.
Acknowledgement This study was funded by Ardea Biosciences/AstraZeneca. Editorial support was provided by PAREXEL and was funded by AstraZeneca.
Disclosure of Interest T. Bardin Grant/research support from: Ipsen, Menarini., Consultant for: AstraZeneca, Ipsen, Menarini, Novartis, Savient, Sobi, Takeda, Cymabay., N. Dalbeth Grant/research support from: AstraZeneca, Fonterra, Novartis., Consultant for: AstraZeneca, Fonterra, Pfizer, Takeda, Crealta, Cymabay., Speakers bureau: AstraZeneca, Teijin., R. Terkeltaub Consultant for: Ardea Biosciences, AstraZeneca, Takeda, Relburn, REVIVE., C. Storgard Employee of: Ardea Biosciences, a member of the AstraZeneca Group., M. Fung Employee of: Ardea Biosciences, a member of the AstraZeneca Group., J. Hu Employee of: Ardea Biosciences, a member of the AstraZeneca Group., F. Perez-Ruiz Consultant for: AstraZeneca, Menarini, Pfizer., Speakers bureau: AstraZeneca, Menarini, Pfizer.