Long Term Safety & Efficacy Study Evaluating The Effect of A4250 in Children With PFIC

Percentage of Positive Pruritus Assessments at the Participant Level Using the Albireo ObsRo Instrument From Weeks 0-4, 0-12, 0-22, 0-24, 0-36, 0-46, 0-48, 0-60, 0-70, and 0-72 (PM Score)

A positive pruritus assessment was defined as a scratching score of \<=1 or at least a 1-point drop from baseline on the Albireo ObsRO instrument. The percentage of positive pruritus assessment was calculated as the number of positive pruritus assessments divided by the total number of reported assessments by each participant multiplied by 100. PM score represents daytime itching/scratching and tiredness.

Time frame: Weeks 0-4, Weeks 0-12, Weeks 0-22, Weeks 0-24, Weeks 0-36, Weeks 0-46, Weeks 0-48, Weeks 0-60, Weeks 0-70, and Weeks 0-72

Change From Baseline in Serum Bile Acids at Weeks 4, 12, 22, 24, 36, 46, 48, 60, 70, 72 and Every 16 Weeks During the Optional Extension Period

Blood samples for analysis of fasting total serum bile acids were drawn at specified timepoints. Participants were to fast (water intake only) for at least 4 hours prior to the collection of samples for serum bile acids. Exceptions were made for infants \<12 months of age if unable to fast for the full 4 hours. Baseline for Cohort 1 placebo/odevixibat, and Cohort 2 groups was defined as the average of last 2 values before the first dose of study treatment in the A4250-008 study. Baseline for Cohort 1 odevixibat/odevixibat group was defined as average of last 2 values before the first dose of study treatment in study A4250-005 (NCT03566238).

Time frame: Baseline and Weeks 4, 12, 22, 24, 36, 46, 48, 60, 70, 72, 88, 104, 120, 136, 152, 168, 184, 200, 216, 232, 248, 264, 280, 296, 312, and 328

Percentage of Positive Pruritus Assessments at the Participant Level Using the Albireo ObsRo Instrument From Weeks 1-4, 5-8, 9-12, 13-16, 17-20, 21-24, 34-36, 44-46, 47-48, 58-60, 68-70, 71-72, and 73-76 (AM and PM Score)

A positive pruritus assessment was defined as a scratching score of \<=1 or at least a 1-point drop from baseline on the Albireo ObsRO instrument. The percentage of positive pruritus assessment was calculated as the number of positive pruritus assessments divided by the total number of reported assessments in the time interval recorded by each participant multiplied by 100.

Time frame: Weeks 1-4, 5-8, 9-12, 13-16, 17-20, 21-24, 34-36, 44-46, 47-48, 58-60, 68-70, 71-72, and 73-76

Percentage of Positive Pruritus Assessments at the Participant Level Using the Albireo ObsRo Instrument (AM Score)

A positive pruritus assessment was defined as a scratching score of \<=1 or at least a 1-point drop from baseline on the Albireo ObsRO instrument. The percentage of positive pruritus assessment was calculated as the number of positive pruritus assessments divided by the total number of reported assessments in the time interval recorded by each participant multiplied by 100. AM score represents night-time itching/scratching and sleep disturbance.

Time frame: Weeks 1-4, 5-8, 9-12, 13-16, 17-20, 21-24, 34-36, 44-46, 47-48, 58-60, 68-70, 71-72, and 73-76

Percentage of Positive Pruritus Assessments at the Participant Level Using the Albireo ObsRo Instrument (PM Score)

A positive pruritus assessment was defined as a scratching score of \<=1 or at least a 1-point drop from baseline on the Albireo ObsRO instrument. The percentage of positive pruritus assessment was calculated as the number of positive pruritus assessments divided by the total number of reported assessments in the time interval recorded by each participant multiplied by 100. PM score represents daytime itching/scratching and tiredness.

Time frame: Weeks 1-4, 5-8, 9-12, 13-16, 17-20, 21-24, 34-36, 44-46, 47-48, 58-60, 68-70, 71-72, and 73-76

Percentage of Responders for Pruritus Assessments Bi-Weekly (AM and PM Score)

A responder is defined as a participant who reports a decrease in pruritus score from unrounded baseline equivalent to or greater than the threshold of meaningful change of 1.0 estimated from the blinded psychometric analysis. The averaged pruritus score was used to calculate the percentage of participants achieving meaningful reduction against the threshold value of 1.0 based on bi-weekly scores. ObsRO instrument was used to assess severity of observed scratching twice a day (AM and PM) with score from 0 to 4 where 0 is no scratching and 4 is worst possible scratching.

Time frame: Weeks 1-2, 3-4, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, 19-20, 21-22, 23-24, 35-36, 47-48, 59-60, and 71-72

Percentage of Responders for Pruritus Assessments Monthly (AM and PM Score)

A responder is defined as a participant who reports a decrease in pruritus score from unrounded baseline equivalent to or greater than the threshold of meaningful change of 1.0 estimated from the blinded psychometric analysis. The averaged pruritus score was used to calculate the percentage of participants achieving meaningful reduction against the thresholds value of 1.0 based on monthly scores. ObsRO instrument was used to assess severity of observed scratching twice a day (AM and PM) with score from 0 to 4 where 0 is no scratching and 4 is worst possible scratching.

Time frame: Weeks 1-4, 5-8, 9-12, 13-16, 17-20, 21-24, 34-36, 45-48, 58-60, and 68-72

Percentage of Participants Achieving a Positive Pruritus Assessment for >50% of the Time Based on the Albireo ObsRO (AM and PM Score)

The percentage of participants who achieved positive pruritus assessment for more than 50% of the time for Weeks 0-72 is reported. A positive pruritus assessment is defined as a scratching score of \<=1 or at least a 1-point decrease from baseline on the Albireo ObsRO instrument based on rounded baseline and was calculated based on reported eDiary data. At each assessment, the AM score was compared to the baseline AM average, and the PM score was compared to the baseline PM average.

Time frame: Week 72

Number of Participants Who Underwent Biliary Diversion Surgery and/or Liver Transplantation

Participants who underwent BDS and/or liver transplantation are reported.

Time frame: Weeks 24, 48, 72, 88, 104, 120, 136, 152, 168, 184, 200, 216, 232, 248, 264, 280, 296, 312, 328, 344, and 360

Change From Baseline in Height Z-Scores During Treatment Period and the Optional Extension Period

Height was measured using certified stadiometer. Change in growth parameters was assessed using linear growth (height) compared to standard growth curve (Z-score) calculated by using the software or methods from the Centers for Disease Control (CDC) website for participants with age \>=2 years old and from the World Health Organization (WHO) website for participants with age \<2 years old. A Z-score was not calculated for participants whose accurate age was not available. Baseline was the last available assessment prior to first dose of study treatment in the A4250-008 study. A Z-score indicates how many standard deviation's (SD) a participant's height measurement, was from the average for their age and sex. A Z-score of 0 represents the median or 50th percentile, while positive or negative values show how far above or below average a measurement was.

Time frame: Baseline and Weeks 12, 24, 36, 48, 60, 70, 72, 88, 104, 120, 136, 152, 168, 184, 200, 216, 232, 248, 264, 280, 296, 312, and 328

Change From Baseline in Weight Z-Scores During Treatment Period and the Optional Extension Period

Weight was measured using certified weight scale. Change in growth parameters was assessed using linear growth (weight) compared to standard growth curve (Z-score), calculated by using the software or methods from the CDC website for participants with age \>=2 years old and from the WHO website for participants with age \<2 years old. A Z-score was not calculated for participants whose accurate age was not available. Baseline was the last available assessment prior to the first dose of study treatment in the A4250-008 study. The Z-score indicates how many SDs a participant's weight measurement, was from the average for their age and sex. A Z-score of 0 represents the median or 50th percentile, while positive or negative values show how far above or below the average a measurement was.

Time frame: Baseline and Weeks 12, 24, 36, 48, 60, 70, 72, 88, 104, 120, 136, 152, 168, 184, 200, 216, 232, 248, 264, 280, 296, 312, and 328

Change From Baseline in Body Mass Index (BMI) Z-Scores During Treatment Period and the Optional Extension Period

BMI was calculated by weight (kg) / height (m)\^2 which were measured by the standardized assessments. Change in growth parameters was assessed using linear growth (BMI) compared to standard growth curve (Z-score), calculated by using the software or methods from the CDC website for participants with age \>=2 years old and from the WHO website for participants with age \<2 years old. A Z-score was not calculated for participants whose accurate age was not available. Baseline was the last available assessment prior to the first dose of study treatment in the A4250-008 study. The Z-score indicates how many SDs a participant's BMI measurement, was from the average for their age and sex. A Z-score of 0 represents the median or 50th percentile, while positive or negative values show how far above or below the average a measurement was.

Time frame: Baseline and Weeks 12, 24, 36, 48, 60, 70, 72, 88, 104, 120, 136, 152, 168, 184, 200, 216, 232, 248, 264, 280, 296, 312, and 328

Number of Participants With Use of Ursodeoxycholic Acid (UDCA) and/or Rifampicin at Weeks 24, 48, and 72

The number of participants with use of UDCA and/or rifampicin are reported.

Time frame: Weeks 24, 48, and 72

Change From Baseline to Week 72 During Treatment Period and During the Optional Extension Period in Pediatric End-Stage Liver Disease (PELD) Score

The PELD score was calculated for children under 12 years of age, ranged across negative to positive values. Calculation of PELD score was done by converting the laboratory parameters: total bilirubin in milligram/deciliter (mg/dL), albumin in gram (g)/dL, and creatinine in mg/dL laboratory parameters were converted to units. PELD score was calculated as 4.80\*ln (total bilirubin)+18.57\*ln \[international normalized ratio (INR)\] - 6.87\*ln (albumin) + 4.36 (if participant \<1 year: scores for participants listed for liver transplantation before the participant's first birthday continued to include the value assigned for age (\<1 year) until the participant reached the age of 24 months)+6.67 (if the participant has growth failure \[\<-2 SD\]). The laboratory values \<1.0 were set to 1.0 for the calculation of PELD score. Lower scores represent less severe hepatic disease. Baseline was the last available assessment prior to the first dose of study treatment in the A4250-008 study.

Time frame: Baseline and Weeks 72, 88, 104, 120, 136, 152, 168, 184, 200, 216, 232, 248, 264, 280, 296, and 312

Change From Baseline to Week 72 During Treatment Period and During the Optional Extension Period in Model for End-stage Liver Disease (MELD) Score for Children 12 Years of Age or Older

MELD score was calculated for children 12 years of age or older ranges from 6 to 40. Calculation of MELD score was done by converting the laboratory parameters in the following units: total bilirubin in mg/dL, albumin in g/dL, and creatinine in mg/dL laboratory parameters were converted to units. MELD score was calculated as 9.57\*ln (creatinine)+3.78\*ln (total bilirubin)+11.2 \*ln (INR)+6.43. Laboratory values \<1.0 were set to 1.0 and serum creatinine values \>4.0 mg/dL were set to 4.0 for calculation of the MELD score. Lower scores represent less severe hepatic disease. Baseline was the last available assessment prior to the first dose of study treatment in the A4250-008 study. All assessments after intercurrent events (premature treatment discontinuation, death, or initiation of rescue treatments such as biliary diversion surgery or liver transplantation) or follow-up assessments (\>= last dose day+15 days) were excluded from analysis.

Time frame: Baseline and Weeks 72, 88, 104, and 120

Change From Baseline to Week 72 in Aspartate Aminotransferase (AST) to Platelet Ratio Index (APRI) Score

The AST to APRI score was calculated as \[(AST in units per liter {U/L})/ (AST upper limit of normal {ULN} in U/L)\] \* 100/ (platelets in 10\^9/L). The APRI score is a way to assess fibrosis of the liver. The lower the APRI score (\< 0.5), the greater the negative predictive value and ability to rule out cirrhosis; the higher the value (\> 1.5) the greater the positive predictive value and ability to rule in cirrhosis. Lower values indicate less severe hepatic fibrosis. Baseline was the last available assessment prior to the first dose of study treatment in the A4250-008 study.

Time frame: Baseline and Week 72

Change From Baseline to Week 72 in Fibrosis-4 (Fib-4) Score

Fib-4 score was calculated as (age \* AST in U/L)/ (platelets in 10\^9/L \*√ ( alanine aminotransferase \[ALT\] in U/L). The FIB-4 score estimates the amount of scarring in the liver. A FIB-4 score \<1.45 has a negative predictive value of 90% for advanced fibrosis (Ishak fibrosis score 4-6 which includes early bridging fibrosis to cirrhosis). In contrast, a FIB-4 score \> 3.25 would have a 97% specificity and a positive predictive value of 65% for advanced fibrosis. Lower values indicate less severe hepatic fibrosis. Baseline was the last available assessment prior to the first dose of study treatment in the A4250-008 study.

Time frame: Baseline and Week 72