A Phase 3 interventional study of Maralixibat in Progressive Familial Intrahepatic Cholestasis (PFIC), sponsored by Mirum Pharmaceuticals, Inc.. Completed at 28 sites in 16 countries. Open to participants aged 1 Year to 18 Years. Per ClinicalTrials.gov, last updated 2026-06-23.
Sponsored by Mirum Pharmaceuticals, Inc. · Phase 3, Interventional, and Treatment
The primary objective of this open label extension study is to evaluate the long-term safety and tolerability of maralixibat.
The study will be conducted at multiple sites in North America, Europe, Asia, and South America.
33 studies on the registry are indexed under Cholestasis, progressive familial intrahepatic 1; 13 are open to participants now.
This study's enrollment of 84 is above the median of 60 across 11 interventional studies indexed under Cholestasis, progressive familial intrahepatic 1.
Browse Cholestasis, progressive familial intrahepatic 1 studies →Mirum Pharmaceuticals, Inc. is the lead sponsor of 40 studies on the registry; 7 are open to participants now.
Of its 12 completed or terminated interventional studies of FDA-regulated products, 11 (92%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
All subjects will receive Maralixibat oral solution
Drug: Maralixibat
All subjects will receive Maralixibat oral solution (up to 600 microgram per kilogram \[mcg/kg\]) twice daily
Mean Change From Baseline Over Time in the Average Morning ItchRO(Obs) Severity Score
The Score on the ItchRo scale is a score on a 5-point scale from 0 (no itch) to 4 (very severe itch)
Time frame: From Baseline to Weeks 75-78
Maintenance of ItchRO(Obs) Response (Weeks 15 - 26)
Maintenance of treatment effect is defined as the proportion of participants in the MRX-MRX treatment group (MRX-502 and MRX-503 data for subjects on MRX in the MRX-502 study) who obtain an ItchRO (Obs) response from Week 15 to Week 26 in Study MRX-503 in the primary cohort and PFIC cohort.
Time frame: Week 15 - 26
Proportion of ItchRO(Obs) Responders Over Time
Proportion of ItchRO responders over time at each study visit using the 4-week study period prior to the visit as per ItchRO(Obs) responder definition.
Time frame: Baseline to EOT
Mean Change From Baseline Over Time in the Average Morning ItchRO(Obs) Frequency Score
The Score on the ItchRo scale is a score on a 5-point scale from 0 (no itch) to 4 (very severe itch)
Time frame: From Baseline to Weeks 75-78
Mean Change From Baseline Over Time in Total Serum Bile Acid (sBA) Levels
Mean change from baseline over time in total serum bile acid (sBA) levels
Time frame: Baseline to week 70
Proportion of Subjects Who Experience an sBA Control Over Time From Week 18 to Week 26
Proportion of subjects who experience an sBA control over time from Week 18 to Week 26
Time frame: From Week 18 to Week 26
Change From Baseline in Height Z-score
Height-for-age Z-score measures a participant's height relative to a reference population of children of the same age and sex. Z-scores were derived using World Health Organization growth charts for participants less than 24 months of age and Centers for Disease Control and Prevention growth charts for participants 24 months of age or older. A Z-score of 0 represents the population mean for age and sex. Positive Z-scores indicate height above the reference population mean, and negative Z-scores indicate height below the reference population mean. Higher Z-scores generally indicate greater linear growth relative to the reference population. Change from baseline was calculated as post-baseline height-for-age Z-score minus baseline height-for-age Z-score.
Time frame: From baseline to Week 70
Change From Baseline in Weight Z-score
Weight-for-age Z-score measures a participant's weight relative to a reference population of children of the same age and sex. Z-scores were derived using World Health Organization growth charts for participants less than 24 months of age and Centers for Disease Control and Prevention growth charts for participants 24 months of age or older. A Z-score of 0 represents the population mean for age and sex. Positive Z-scores indicate weight above the reference population mean, and negative Z-scores indicate weight below the reference population mean. Higher Z-scores generally indicate greater body weight relative to the reference population. Change from baseline was calculated as post-baseline weight-for-age Z-score minus baseline weight-for-age Z-score.
Time frame: From Baseline to Week 70
A total of 84 participants were enrolled at 28 sites across 16 countries (Argentina, Austria, Belgium, Brazil, Canada, Colombia, France, Germany, Italy, Lebanon, Mexico, Poland, Singapore, Turkey, United Kingdom, United States)
| Milestone | Maralixibat |
|---|---|
| Started | 84 |
| Completed | 45 |
| Not completed | 39 |
| Withdrew: Withdrawal by subject | 7 |
| Withdrew: Physician decision | 3 |
| Withdrew: Adverse event | 8 |
| Withdrew: Liver transplant | 16 |
| Withdrew: Lost to follow-up | 1 |
| Withdrew: Disease progression | 2 |
| Withdrew: Rolled over under drug interruption | 1 |
| Withdrew: Initiation/dose increase of medication to treat pruritus or cholestatic liver disease | 1 |
The Score on the ItchRo scale is a score on a 5-point scale from 0 (no itch) to 4 (very severe itch)
| score on a scale | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Mean Change From Baseline Over Time in the Average Morning ItchRO(Obs) Severity Score | -1.633 ± 1.4416 | -1.602 ± 1.3649 |
Maintenance of treatment effect is defined as the proportion of participants in the MRX-MRX treatment group (MRX-502 and MRX-503 data for subjects on MRX in the MRX-502 study) who obtain an ItchRO (Obs) response from Week 15 to Week 26 in Study MRX-503 in the primary cohort and PFIC cohort.
| percentage of participants | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Week 15-18 | 71.4 | 69.7 |
| Week 19-22 | 64.3 | 72.7 |
| Week 23-26 | 64.3 | 69.7 |
Proportion of ItchRO responders over time at each study visit using the 4-week study period prior to the visit as per ItchRO(Obs) responder definition.
| percentage of participants | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Week 1-6 | 57.1 | 50 |
| Week 7-10 | 67.9 | 65 |
| Week 11-14 | 67.9 | 63.3 |
| Week 15-18 | 75 | 66.7 |
| Week 19-22 | 67.9 | 68.3 |
| Week 23-26 | 64.3 | 63.3 |
| Week 39-42 | 78.6 | 71.7 |
| Week 51-54 | 71.4 | 66.7 |
| Week 63-66 | 57.1 | 58.3 |
| Week 75-78 | 57.1 | 53.3 |
| Week 87-90 | 50 | 48.3 |
| Week 99-102 | 57.1 | 46.7 |
| Week 111-114 | 21.4 | 26.7 |
| Week 123-126 | 14.3 | 20 |
The Score on the ItchRo scale is a score on a 5-point scale from 0 (no itch) to 4 (very severe itch)
| score on a scale | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Mean Change From Baseline Over Time in the Average Morning ItchRO(Obs) Frequency Score | -1.644 ± 1.4451 | -1.608 ± 1.3848 |
Mean change from baseline over time in total serum bile acid (sBA) levels
| umol/L | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Mean Change From Baseline Over Time in Total Serum Bile Acid (sBA) Levels | -150.064 ± 213.7437 | -111.473 ± 188.1880 |
Proportion of subjects who experience an sBA control over time from Week 18 to Week 26
| percentage of participants | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Week 18 | 42.9 | 40 |
| Week 22 | 42.9 | 38.3 |
| Week 26 | 46.4 | 43.3 |
| Average of Weeks 18, 22, 26 | 42.9 | 40 |
Height-for-age Z-score measures a participant's height relative to a reference population of children of the same age and sex. Z-scores were derived using World Health Organization growth charts for participants less than 24 months of age and Centers for Disease Control and Prevention growth charts for participants 24 months of age or older. A Z-score of 0 represents the population mean for age and sex. Positive Z-scores indicate height above the reference population mean, and negative Z-scores indicate height below the reference population mean. Higher Z-scores generally indicate greater linear growth relative to the reference population. Change from baseline was calculated as post-baseline height-for-age Z-score minus baseline height-for-age Z-score.
| Z-Score | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Change From Baseline in Height Z-score | 0.486 ± 0.6665 | 0.335 ± 0.6229 |
Weight-for-age Z-score measures a participant's weight relative to a reference population of children of the same age and sex. Z-scores were derived using World Health Organization growth charts for participants less than 24 months of age and Centers for Disease Control and Prevention growth charts for participants 24 months of age or older. A Z-score of 0 represents the population mean for age and sex. Positive Z-scores indicate weight above the reference population mean, and negative Z-scores indicate weight below the reference population mean. Higher Z-scores generally indicate greater body weight relative to the reference population. Change from baseline was calculated as post-baseline weight-for-age Z-score minus baseline weight-for-age Z-score.
| Z-Score | The Primary Cohort | PFIC Cohort |
|---|---|---|
| Change From Baseline in Weight Z-score | 0.518 ± 0.9349 | 0.330 ± 0.7421 |
Collected over From the first dose through 14 days after the last dose of maralixibat, up to approximately 260 weeks.. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Maralixibat | 2/84 (2.4%) | 25/84 (29.8%) | 84/84 (100%) |
| Event | Maralixibat |
|---|---|
| GastroenteritisInfections and infestations | 4/84 |
| Progressive familial intrahepatic cholestasisCongenital, familial and genetic disorders | 2/84 |
| Cholecystitis acuteHepatobiliary disorders | 2/84 |
| Corona virus infectionInfections and infestations | 2/84 |
| DiarrhoeaGastrointestinal disorders | 1/84 |
| HaematocheziaGastrointestinal disorders | 1/84 |
| Oesophageal varices haemorrhageGastrointestinal disorders | 1/84 |
| Disease progressionGeneral disorders and administration site conditions | 1/84 |
| Oedema peripheralGeneral disorders and administration site conditions | 1/84 |
| Biliary colicHepatobiliary disorders | 1/84 |
| Event | Maralixibat |
|---|---|
| PyrexiaGeneral disorders and administration site conditions | 40/84 |
| DiarrhoeaGastrointestinal disorders | 39/84 |
| CoughRespiratory, thoracic and mediastinal disorders | 28/84 |
| Abdominal painGastrointestinal disorders | 23/84 |
| NasopharyngitisInfections and infestations | 21/84 |
| PruritusSkin and subcutaneous tissue disorders | 21/84 |
| InfluenzaInfections and infestations | 16/84 |
| Upper respiratory tract infectionInfections and infestations | 16/84 |
| Blood bilirubin increasedInvestigations | 16/84 |
| Alanine aminotransferase increasedInvestigations | 14/84 |
| Age, Customized(Participants) | Maralixibat |
|---|---|
| Infants and toddlers (28 days - 23 months) | 18 |
| Children (2-11 years) | 62 |
| Adolescents (12-17 years) | 4 |
| Sex: Female, Male(Participants) | Maralixibat |
|---|---|
| Female | 48 |
| Male | 36 |
| Ethnicity (NIH/OMB)(Participants) | Maralixibat |
|---|---|
| Hispanic or Latino | 33 |
| Not Hispanic or Latino | 48 |
| Unknown or Not Reported | 3 |
| Region of Enrollment(participants) | Maralixibat |
|---|---|
| Colombia | 5 |
| Argentina | 3 |
| Singapore | 2 |
| United States | 18 |
| United Kingdom | 2 |
| Lebanon | 13 |
| Canada | 2 |
| Austria | 2 |
| Turkey | 2 |
| Belgium | 2 |
| Poland | 5 |
| Brazil | 10 |
| Mexico | 8 |
| Italy | 5 |
| France | 3 |
| Germany | 2 |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
Ran from Jan 2020 to primary completion in Apr 2025, 63 months.
Results were first posted in Jun 2026, 1 year 2 months after primary completion.
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Studies of the drug tested here: Maralixibat
Cholestasis, progressive familial intrahepatic 1 →