Open Label Study to Evaluate Efficacy and Long Term Safety of LUM001 (Maralixibat) in the Treatment of Cholestatic Liver Disease in Patients With Progressive Familial Intrahepatic Cholestasis

1\. Male or female subjects between the ages of 12 months and 18 years inclusive.

2\. Diagnosis of PFIC based on:

1. Intrahepatic cholestasis manifest by total serum bile acid \>3x upper limit of normal (ULN) for age and, b or c:

2. Two documented mutant alleles in ATP8B1, or ABCB11.

3. Evidence of chronic liver disease, excluding those listed in (see Section 16.3), with one or more of the following criteria:

1. Duration of biochemical or clinical abnormalities of \>6 months, or

2. Pathologic evidence of progressive liver disease, or

3. Sibling of known individual affected by PFIC (predicted to be chronic).

3\. GGTP \<100 IU/L at screening. 4. Females of childbearing potential must have a negative urine or serum pregnancy test \[β human chorionic gonadotropin (β-hCG)\] during screening and a negative urine pregnancy test at the Baseline (Day 0) visit.

5\. Males and females of child-bearing potential who are sexually active, or are not currently sexually active during the study, but become sexually active during the period of the study and 30 days following the last dose of study drug, must agree and use acceptable contraception during the trial, as described in Section 8.7.1. of the protocol 6. Informed consent and assent (per IRB/EC) as appropriate. 7. Access to phone for scheduled calls from study site. 8. Caregivers and children above the age of assent must have the ability to read and understand one of the following languages: English, Spanish, US Spanish, French, German or Polish.

9\. Subjects expected to have a consistent caregiver(s) for the duration of the first 13 weeks of the study.

10\. Caregivers (and age appropriate subjects) must be willing and able to use an eDiary device as required by the study. To accommodate potential cultural restrictions within the FIC1 affected population a paper version of the ItchRO diary will be made available.

11\. Caregivers (and age appropriate subjects) using the eDiary must digitally accept the licensing agreement in the eDiary software at the outset of the study.

12\. Caregivers (and age appropriate subjects) must complete at least 10 eDiary reports (morning or evening) during each of two consecutive weeks of the screening period, prior to assignment (maximum possible reports = 14 per week). Subjects using a paper diary must complete the same number of reports within the same timeframe

What this study is about