Safety Study of Ornithine Phenylacetate to Treat Patients With Acute Liver Failure/Severe Acute Liver Injury

There is strong experimental and clinical rationale for the use of ammonia-lowering therapies
in ALF. Ammonia is normally produced in the gut and transformed by the liver into urea. As
the liver fails, ammonia increases in the systemic circulation and enters into the brain. The
result of a rapid rise in ammonia or related compounds in the cerebral circulation is hepatic
encephalopathy (HE), a reversible neuropsychiatric condition that ranges in severity from
mild impairment in attention, to delirium, the development of cerebral edema, coma and death.
This is a Phase 2a, multi-center, open-label study, conducted in two cohorts in patients
diagnosed with acute liver failure/acute liver injury (ALF/ALI) who meet inclusion/exclusion
criteria. This study is designed to provide data on OCR-002 with regards to

- the effect on circulating ammonia levels in patients with acute liver failure with and
without impaired renal function at different doses after single and continuous infusion

- safety and dose tolerability as well as

- providing data on the metabolites, glutamine and phenylacetylglutamine in this patient
population.

It is anticipated that this early efficacy, safety, tolerability,
Pharmacokinetic/Pharmacodynamic (PK/PD) and dose-ranging study will lead to a Phase 3
development program for the use of OCR-002 in the treatment of hyperammonemia due to ALF. No
clinical outcome measures will be formally studied because of the small sample size.

Inclusion Criteria:

1. Men and women, ages 18-65 (have not reached their 66th birthday).

2. Acute liver failure, defined as the development of coagulopathy (International
normalized ratio [INR] ≥1.5) with encephalopathy in a patient with no prior history of
liver disease, with onset of symptoms within 28 days of the inciting event. Patients
may have either a history of acetaminophen overdose (defined as >4 g/day within 7 days
of presentation) and/or detectable acetaminophen levels in the serum, with a pattern
of liver function tests typical for acetaminophen toxicity (bilirubin < 10 mg/dL and
alanine aminotransferase (ALT) ≥1000 IU/L), or a diagnosis of hepatitis A, hepatitis
B, drug-induced liver injury, autoimmune hepatitis or indeterminate cause based on
standard criteria.

3. ALI patients may also be enrolled (those meeting the above criteria plus coagulopathy
(INR ≥ 2.0) and no evidence of encephalopathy)

4. Written informed consent from the patient (ALI) or patient's legally authorized
representative or family member if he/she is considered encephalopathic (ALF).

5. Ammonia level ≥60 μmol/L at baseline (within 8h prior to T0/initiation of infusion).

6. Serum creatinine levels as follows:

1. Cohort 1: Creatinine ≤1.5 mg/dL; and

2. Cohort 2: Creatinine >1.5 mg/dL and <10mg/dL.

7. Mean arterial pressure of >65 mmHg.

Exclusion Criteria:

1. History of chronic liver disease.

2. Signs of overt cerebral herniation, or uncontrolled intracranial hypertension by
intracranial pressure (ICP) monitoring (if applicable).

3. Evidence of Wilson's disease, alcoholic hepatitis, biliary obstruction, ischemic
hepatitis, severe acute renal tubular necrosis (ATN) due to shock, or any patient with
ongoing hypotension.

4. Significant gastrointestinal bleeding (coffee grounds per nasogastric tube and/or
melena).

5. Hemodynamic instability, defined by a mean arterial pressure of <65 mmHg.

6. Cardiopulmonary complications such as pulmonary edema, aspiration pneumonia, heart
failure.

7. QT interval of >500msec at baseline EKG.

8. Pregnancy.

9. History of malignancy that has not been cured or any cancer in remission for less than
1 within the past 5 year. Non-melanoma skin cancers do not preclude participation in
the trial.

10. Concomitant administration of drugs known to interfere with renal excretion of
phenylacetylglutamine or those medications that may induce hyperammonemia such as
haloperidol, valproic acid and systemic corticosteroids (prohibited during the study).
Alternative ammonia modifying agents such as lactulose and rifaximin are not
considered standard of care and are prohibited during the study period.

11. Any other health condition that would preclude participation in the study in the
judgment of the principal investigator.