The FDA has granted orphan drug designation to Lumena Pharmaceuticals for LUM001, a drug being developed for treatment of four rare liver diseases, including PSC, according to this press release.
A short explanation of what that means is found in this article.
http://www.healio.com/hepatology/autoimmune-cholestatic-biliary-diseases/news/online/%7B6c5bebc5-d1a3-4f13-8eec-10885e950ccb%7D/liver-disease-drug-receives-orphan-drug-designation-from-fda
Regards,
Chaim Boermeester, Israel