To Assess Safety, Tolerability and Efficacy of LJN452 in Patients With Primary Bile Acid Diarrhea.

Key Inclusion Criteria:

- A history of diarrheal symptoms for at least 3 months prior to dosing - Average stool
frequency of at least 2 per day when off therapy AND Average stool form of >5 on
Bristol Stool Chart.

- Previous laboratory or radiological confirmation of bile acid malabsorption with
either fecal bile acid loss OR 7 day 75Selenium homocholic acid taurine (75SeHCAT)
retention.

- Age ≥ 18 years.

Key Exclusion Criteria:

- Patients with other diagnoses leading to diarrhea, including colorectal neoplasia,
ulcerative colitis, Crohn's disease, celiac disease, chronic pancreatitis,
drug-induced diarrhea or active infection AND Patients who have not been investigated
by standard clinical assessments to exclude these disorders.

- Treatment with bile acid sequestrants (colestyramine, colestipol, colesevelam) for 2
weeks before the first dose of LJN452. A washout of 14 days for these agents will be
allowed before first dosing.

- Women of child-bearing potential, defined as all women physiologically capable of
becoming pregnant.

- A positive Hepatitis B surface antigen or Hepatitis C test result.

- History of immunodeficiency diseases, including a positive HIV (ELISA and Western
blot) test result.