The purpose of this Phase IIa study is to evaluate the safety and tolerability of ALLN-346 in subjects with hyperuricemia in an inpatient, controlled setting.

This is a Phase II, 7-day, randomized, double-blind, placebo-controlled study of orally administered ALLN-346 in subjects with hyperuricemia, with subpopulations to include generally healthy hyperuricemic subjects with normal kidney function and those with mild to moderate chronic kidney disease (CKD). Study will take place at a clinical pharmacology unit (CPU). The study will have two Parts. Part 1 will include subjects with serum urate ≥ 6.8 mg/dL and eGFR ≥ 60 mL/minute/1.73 m2 (subjects with eGFR of stage 2 CKD and with normal kidney function). Part 2 will include subjects with serum urate ≥ 6.8 mg/dL and eGFR 45-100 mL/minute/1.73 m2 (eGFR of CKD Stages 2- 3a).

The study will evaluate safety, tolerability, pharmacokinetics (lack of absorption) and pharmacodynamics of ALLN-346.

Inclusion Criteria:

• Male or female, age 18 to 55 years
• sUA level ≥ 6.8 mg/dL at Screening (hyperuricemia), with or without a diagnosis of gout
• Not pregnant, not capable of pregnancy, not nursing, and agrees to use an effective method of contraception; males subjects must agree to abstain from sperm donation
• Normal non-clinically significant abnormalities in vital signs
• Normal clinical laboratory test results and ECG, which are not considered to be clinically significant

Exclusion Criteria:

• Screening eGFR of <60 mL/minute/1.73 m2 for Part 1, and for Part 2 Screening eGFR outside the range of 45-100 mL/minute/1.73 m2.
• History or clinical manifestations of significant metabolic, hematological, pulmonary, cardiovascular, gastrointestinal, neurologic, hepatic, urological, or psychiatric disorders.
• Presence or history of any other condition (including surgery) known to interfere with the absorption, distribution, metabolism, or excretion of medicines
• Currently taking any urate-lowering medication within 4 weeks prior to Day 1 (first dosing day)
• Prior uricase therapy or exposure to recombinant uricase
• Clinically significant abnormal findings on electrocardiogram (ECG)
• Positive test result for hepatitis B surface antigen, hepatitis C virus antibody, or human immunodeficiency virus (HIV) antibody
• Received treatment with or exposure to an Investigational drug or device within 30 days - prior to or during Screening
• Prior dosing in ALLN-346 clinical study
• Per Investigator judgment, is not an ideal clinical study candidate

Subjects, Investigators and laboratories involved in the conduct of the study will be blinded to subject treatment assignment.