A Study of the Safety, Efficacy and Pharmacokinetics of Glycerol Phenylbutyrate in Pediatric Subjects Under 2 Years of Age With Urea Cycle Disorders

Amgen27 enrolled

Overview

This is an open-label study consisting of a transition period to RAVICTI, followed by a safety extension period for at least 6 months and up to 24 months of treatment with RAVICTI, depending on age at enrollment. It is designed to capture information important for evaluating safety, pharmacokinetics and efficacy in young children. Subjects who are followed by or referred to the Investigator for management of their UCD. Subjects eligible for this study will include patients ranging from newborn to \< 2 years of age with either a diagnosed or clinically suspected UCD.

Study acquired from Horizon in 2024.

Study Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Urea Cycle Disorder

Interventions

Eligibility

Sex: ALLMin age: 1 DayMax age: 2 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Male and female subjects up to 2 years of age * Signed informed consent by subject's parent/legal guardian * UCD diagnosis or suspected diagnosis of any subtype, except N-acetyl glutamate synthetase deficiency. If UCD has not been previously confirmed by genetic testing, consent must be obtained from parent/legal guardian prior to perform genetic testing. If genetic testing is inconsistent with or excludes a UCD diagnosis, the subject will be withdrawn from the study. Exclusion Criteria: * Use of any investigational drug within 30 days of Day 1 * Uncontrolled infection (viral or bacterial) or any other condition known to precipitate hyperammonemic crises. Once these precipitating factors are medically controlled, patients presenting in crisis are eligible. * Any clinical or laboratory abnormality of Grade 3 or greater severity according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.03, except Grade 3 elevations in ammonia and liver enzymes, defined as levels 5-20 times the upper limit of normal in alanine aminotransferase (ALT), aspartate aminotransferase (AST), or gamma glutamyl transpeptidase (GGT) in a clinically stable subject * Any clinical or laboratory abnormality or medical condition that, at the discretion of the Investigator, may put the subject at increased risk by participating in this study * Known hypersensitivity to phenylacetate (PAA) or phenylbutyrate (PBA) * Liver transplantation, including hepatocellular transplant * Subjects on hemodialysis at time of initiating RAVICTI * Subjects on RAVICTI for UCD management * Currently treated with Carbaglu® (carglumic acid)

Locations (17)

Kaiser Permanente Regional Metabolic Center

Los Angeles, California, United States

Stanford Center for Clinical & Translational Research & Education

Palo Alto, California, United States

Children's National Medical Center

Washington D.C., District of Columbia, United States

Shands at University of Florida

Gainesville, Florida, United States

Emory University

Decatur, Georgia, United States

Indiana University

Indianapolis, Indiana, United States

Maine Medical Center

Portland, Maine, United States

Children's Hospital of Michigan

Detroit, Michigan, United States

University of Minnesota

Minneapolis, Minnesota, United States

Mount Sinai School of Medicine

New York, New York, United States

...and 7 more locations

Outcomes

Primary Outcomes

Percentage of Participants With Successful Transition to RAVICTI With Controlled Ammonia (i.e. No Clinical Symptoms and Ammonia < 100 μmol/L): Cohort of 2 Months to <2 Years Participants

The percentage of participants with successful transition is based on Investigator response to the question, "Has transition to 100% RAVICTI been successful with controlled ammonia?" For participants 2 months of age and older, after a minimum of 24 hours of ammonia monitoring following the first full dose of RAVICTI alone, the participant was effectively transitioned when following conditions were met: no signs and symptoms of hyperammonemia; ammonia level less than 100 μmol/L (without normalization of ammonia, ie, without conversion of values from local laboratories with varying normal ranges to standardized values); and eligible for discharge per Investigator judgment.

Time frame: Up to Day 4

Percentage of Participants With Successful Transition to RAVICTI With Controlled Ammonia (i.e. No Clinical Symptoms and Ammonia < 100 μmol/L): Cohort of 0 Months to <2 Months Participants

The percentage of participants with successful transition is based on Investigator response to the question, "Has transition to 100% RAVICTI been successful with controlled ammonia?" For participants \< 2 months of age, after a minimum of 24 hours of ammonia monitoring following the first full dose of RAVICTI alone, the participant was effectively transitioned when following conditions were met: no signs and symptoms of hyperammonemia; ammonia level less than 100 μmol/L (without normalization of ammonia, ie, without conversion of values from local laboratories with varying normal ranges to standardized values); and eligible for discharge per Investigator judgment.

Time frame: Up to Day 4

Secondary Outcomes

Rate of Hyperammonemic Crises (HACs): Cohort of 2 Months to <2 Years Participants

HAC is defined having signs and symptoms consistent with hyperammonemia (such as but not limited to frequent vomiting, nausea, headache, lethargy, irritability, combativeness, and/or somnolence) associated with high blood ammonia and requiring medical intervention. Rate of HACs per 6 months during the safety extension is calculated as sum of (number of HAC) / sum of (days during first 6 months starting on Day 8 or number days on RAVICTI, whichever is less) across all participants in the corresponding group.

Time frame: Day 8 through up to Month 6

Number of Participants With Treatment-Emergent Adverse Events (TEAEs), Serious TEAEs, Deaths, and Discontinuations Due to TEAEs: Cohort of 2 Months to <2 Years Participants

An adverse event (AE) is any untoward medical occurrence, whether or not the event is considered related to the study drug. A serious AE is any AE that: results in death; is life threatening; requires hospitalization or prolongation of existing hospitalization; results in disability/incapacity; is a congenital anomaly/birth defect; is an important medical event. TEAEs are defined as AEs with an onset date on or after the first dose of study medication until study discontinuation. The Investigator assessed the causal relationship of each TEAE to the study drug as not related, possibly related, or probably related.

Time frame: From the first dose of study treatment through 30 days after the final dose (mean [SD] duration of treatment was 9.13 [6.838] months).

Amino Acid Assessment: Baseline and Change From Baseline in Glutamate Up to Month 24: Cohort of 2 Months to <2 Years Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Glutamine Up to Month 24: Cohort of 2 Months to <2 Years Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Sum of Glutamine and Glutamate Up to Month 24: Cohort of 2 Months to <2 Years Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Isoleucine Up to Month 24: Cohort of 2 Months to <2 Years Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Leucine Up to Month 24: Cohort of 2 Months to <2 Years Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Valine Up to Month 24: Cohort of 2 Months to <2 Years Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 24

Assessment of Growth and Development: Baseline and Change From Baseline in Body Mass Index (BMI) Z-Score Up to Month 24: Cohort of 2 Months to <2 Years Participants

To assess any effect of study drug treatment on growth, Z-scores were calculated to express the deviation from a reference population for BMI. The Z-scores are based on the World Health Organization's Child Growth Standards charts. Negative Z-scores indicate lower than typical for age and gender while positive scores indicate higher than typical for age and gender.

Time frame: Baseline, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Assessment of Growth and Development: Baseline and Change From Baseline in Body Surface Area (BSA) Z-Score Up to Month 24: Cohort of 2 Months to <2 Years Participants

To assess any effect of study drug treatment on growth, Z-scores were calculated to express the deviation from a reference population for BSA. The Z-scores are based on weight-for-length charts. Negative Z-scores indicate lower than typical for age and gender while positive scores indicate higher than typical for age and gender.

Time frame: Baseline, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Plasma Phenylbutyrate/Phenylbutyric Acid (PBA) Maximum Plasma Concentration (Cmax) on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PBA Minimum Plasma Concentration (Cmin) on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PBA Area Under the Curve From Time Zero to the Time of Last Quantifiable Concentration (AUC[0-last]) on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PBA Time to Cmax (Tmax) on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma Phenylacetate/Phenylacetic Acid (PAA) Cmax on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAA Cmin on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAA AUC(0-last) on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAA Tmax on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma Phenylacetylglutamine (PAGN) Cmax on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAGN Cmin on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAGN AUC(0-last) on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAGN Tmax on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Assessment of Urinary PAGN Concentrations on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 0.5 and 1 hour, 1.5 and 2.5 hours, 4 and 6 hours, 7.5 and 8.5 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Assessment of Urinary PAGN Concentrations Up to End of Trial: Cohort of 2 Months to <2 Years Participants

Time frame: Day 7, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, End of Trial (up to Month 18)

Assessment of Urinary PAA Concentrations on the First Full Day of RAVICTI Dosing: Cohort of 2 Months to <2 Years Participants

Time frame: Hour 0 and between 0.5 and 1.5 hours, 1.5 and 2.5 hours, 4 and 6 hours, 7.5 and 8.5 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Assessment of Urinary PAA Concentrations Up to End of Trial: Cohort of 2 Months to <2 Years Participants

Time frame: Day 7, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 15, Month 18, End of Trial (up to Month 18)

Rate of HACs: Cohort of 0 Months to <2 Months Participants

HAC is defined as having signs and symptoms consistent with hyperammonemia (such as but not limited to frequent vomiting, nausea, headache, lethargy, irritability, combativeness, and/or somnolence) associated with high blood ammonia and requiring medical intervention. Rate of HACs per 6 months during the safety extension was calculated as sum of (number of HAC) / sum of (days during first 6 months starting on Day 8 or number days on RAVICTI, whichever is less) across all participants in the corresponding group.

Time frame: Day 8 through up to Month 6

Number of Participants With TEAEs, Serious TEAEs, Deaths, and Discontinuations Due to TEAEs: Cohort of 0 Months to <2 Months Participants

An AE is any untoward medical occurrence, whether or not the event is considered related to the study drug. A serious AE is any AE that: results in death; is life threatening; requires hospitalization or prolongation of existing hospitalization; results in disability/incapacity; is a congenital anomaly/birth defect; is an important medical event. TEAEs are defined as AEs with an onset date on or after the first dose of study medication until study discontinuation. The Investigator assessed the causal relationship of each TEAE to the study drug as not related, possibly related, or probably related.

Time frame: From the first dose of study treatment through 30 days after the final dose (mean [SD] duration of treatment was 10.67 [6.142] months).

Amino Acid Assessment: Baseline and Change From Baseline in Glutamate Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Glutamine Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Sum of Glutamine and Glutamate Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Isoleucine Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Leucine Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Amino Acid Assessment: Baseline and Change From Baseline in Valine Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Day 7, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Assessment of Growth and Development: Baseline and Change From Baseline in BMI Z-Score Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Assessment of Growth and Development: Baseline and Change From Baseline in BSA Z-Score Up to Month 24: Cohort of 0 Months to <2 Months Participants

Time frame: Baseline, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, Month 18, Month 24

Plasma PBA Cmax on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PBA Cmin on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PBA AUC(0-last) on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PBA Tmax on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAA Cmax on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAA Cmin on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAA AUC(0-last) on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAA Tmax on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAGN Cmax on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAGN Cmin on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAGN AUC(0-last) on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Plasma PAGN Tmax on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Time frame: Hour 0 and between 4 and 6 hours, 8 hours, and between 12 and 24 hours after the first dose of the day on Day 1 for stable participants and on Day 2 for participants in HAC

Assessment of Urinary PAGN Concentrations on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Assessment of Urinary PAGN Concentrations Up to End of Trial: Cohort of 0 Months to <2 Months Participants

Time frame: Day 7, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 12, Month 15, End of Trial (up to Month 15)

Assessment of Urinary PAA Concentrations on the First Full Day of RAVICTI Dosing: Cohort of 0 Months to <2 Months Participants

Assessment of Urinary PAA Concentrations Up to End of Trial: Cohort of 0 Months to <2 Months Participants

Time frame: Day 7, Month 1, Month 2, Month 3, Month 4, Month 5, Month 6, Month 9, Month 15, End of Trial (up to Month 15)