Evaluate the Effect of ALLN-177 in Reducing Urinary Oxalate in Patients With Hyperoxaluria and Kidney Stones

This is a multicenter, randomized, double-blind, placebo controlled study to evaluate the
efficacy of ALLN 177 compared with placebo in reducing the urinary excretion of oxalate in
subjects with secondary hyperoxaluria and kidney stones. ALLN-177 is an orally administered
form of oxalate decarboxylase. The goal of therapy with ALLN-177 is to reduce urinary oxalate
excretion by decreasing the absorption of oxalate from the gastrointestinal tract.

Eligible subjects will be randomized to 7 days of treatment with a dose ALLN-177 or placebo
and following a washout period, crossed over to an alternate treatment. Urinary oxalate
excretion will be assessed by 24-hr urine collections throughout the study.

The study allows for up to 60 subjects.

Inclusion Criteria:

- History of enteric or idiopathic hyperoxaluria and at least one kidney stone within
the past 2 years

- Hyperoxaluria at screening

- May be taking drugs for the prevention of stone disease

Exclusion Criteria:

- Hyperuricosuria

- Glomerular filtration rate < 55 mL/min/1.73m2

- Hypercalcemia or hypothyroidism

- Obstructive uropathy, chronic urosepsis, renal failure, renal tubular acidosis,
primary hyperparathyroidism, primary hyperoxaluria, pure uric acid and cystine stones,
and/or medullary sponge kidney

- Treatment with cholestyramine

- Average daily dietary intake of oxalate <75 mg per day