This is a phase 2 study of HPN-100 in subjects with hepatic encephalopathy (HE) consisting of an open label safety lead-in (Part A), followed by randomized, double-blind, placebo-controlled treatment (Part B).

Part A: Open-label, dose-escalation lead-in to assess HPN-100 safety and PK Approximately 10 subjects with HE and cirrhosis classified as Child Pugh B or C will undergo a one-step dose escalation over 4 weeks. Subjects will initially receive 6 mL HPN-100 BID for 1 week. On Day 7 and following satisfactory safety assessment of the subject, the dose will be escalated to 9 mL BID for an additional 3 weeks.

In addition to a safety assessment, subjects will undergo 12-hour PK assessments on Days 7 and 28, with sampling at the following time points (relative to the first dose): 0 (pre-first daily dose of HPN-100), 2, 4, 8 (approximately 2 hours before the second daily dose of HPN 100), and 12 hours post-first dose (approximately 2 hours after the second daily dose of HPN-100). Additional PK samples will be collected on Days 8, 15, and 21 (at pre-first dose and 4 hours post-first dose).

The DSMB will review all safety information, including laboratory values, to determine if Part B may be initiated.

Subjects enrolled in Part A may be eligible for Part B as long as they meet the eligibility criteria.

Part B: Randomized, double-blind assessment of HPN-100 in HE subjects Subjects who meet all entry criteria and are judged to be compliant with their prescribed SOC will be eligible for randomization to receive either HPN-100 or matching placebo for 16 weeks. Efficacy will be assessed by the proportion of subjects experiencing episodes of HE, as well as by other outcome measures, including daily home assessments.

Study acquired from Horizon in 2024.

Inclusion Criteria:

• Subjects aged 18 and over
• Clinical diagnosis of cirrhosis of any cause
• Potential to benefit from HE treatment
• History of greater than or equal to 2 documented episodes of WH Grade 2 or more HE within the past 6 months, at least one of which occurred within the preceding 3 months
• No change in other HE-specific medications within 1 week before randomization
• Able to give informed consent and comply with study activities
• Availability of at least one designated family member or caregiver who is capable of and willing to assume responsibility for facilitating subject compliance with study procedures
• All females of childbearing age and all sexually active males must agree to use an acceptable method of contraception throughout the study.

Exclusion Criteria:

• Use of any investigational drug within 30 days
• Use of prohibited medications
• Uncontrolled infection
• Active GI bleeding or a history of GI bleeding requiring blood transfusion (> 2 units) within 3 months
• Transjugular intrahepatic portosystemic shunt (TIPS) placement or revision within the past 90 days
• Recreational drug use or alcohol consumption for subjects with a history of alcohol or drug abuse within 6 months
• Lactating and/or pregnant females
• Active malignancy
• Clinically significant bowel disease, including obstruction, inflammatory bowel disease, or malabsorption
• Expected to undergo transplantation within 6 months
• Model for end-stage liver disease (MELD) score of > 25

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.