Safety, Efficacy, and Pharmacokinetics of HP501 in Healthy Volunteers and Hyperuricemic Patients: A Phase I/IIa Study

Context: Uricosuric agents are the typical approach to the control of hyperuricemia; however, their use has been eclipsed by adverse reactions, and a safer uricosuric drug is badly needed.

Objective: HP501 is a novel renal urate transporter 1 inhibitor for the treatment of hyperuricemia. In this first-in-human study, we investigated the safety, efficacy, and pharmacokinetics of HP501 in healthy volunteers and hyperuricemic patients.

Methods: The placebo-controlled, double-blind, randomized, 3-part, phase I/IIa study consists of a single ascending dose (SAD) part with 32 participants, a multiple ascending dose part with 48 participants, and a drug-drug interaction part with 20 participants. Effects of food in healthy volunteers administered 45 mg HP501 in the fed state were also assessed in the SAD part.

Results: A total of 68 healthy volunteers and 32 hyperuricemic patients were enrolled. HP501 appeared to be safe and well tolerated in both groups. In hyperuricemic patients dosed with 45 mg HP501 over 10 days, 2/10 and 3/10 patients had elevated AST (< 2 times upper limit of normal [ULN]) and ALT (< 2.5 times ULN), respectively. No dose-limiting adverse events were observed. Across doses of HP501 from 5 to 60 mg, the concentrations of serum uric acid (sUA) are reduced by a maximum of about 50%. HP501 exhibited predictable pharmacokinetics across different dose levels in healthy volunteers or hyperuricemic patients. HP501 and febuxostat have obvious synergistic sUA-lowering effects with no apparent pharmacokinetics interaction.

Conclusion: HP501 was effective at reducing sUA in healthy volunteers and hyperuricemic patients with a tolerable safety profile, warranting further development.