By Mrinalika Roy and Bhanvi Satija

(Reuters) – Mirum Pharmaceuticals (NASDAQ:) Inc said its drug became the first U.S. approved therapy for treating itching in patients with rare liver disorder Alagille syndrome (ALGS), and would be available for distribution immediately.

The company’s shares were temporarily halted prior to the approval, but rose 8.8% to $20.40 upon resumption of trading on Wednesday.

Chris Peetz, Chief Executive Officer of Mirum said that the itching can be very devastating for families and children with the disease. He also stated that liver transplant decisions are influenced by itching.

Mirum officials stated there were currently between 2,000 and 2,500 ALGS-afflicted children in the United States. They estimate that the total market potential for this indication is approximately $500 million.

Mani Faroohar, a SVB Leerink analyst, told Reuters Mirum’s oral medication maralixibat will be sold at “about a third of a million dollars annually,” which is typical for rare diseases this small.

The drug will be sold under the brand Livmarli and could reach $400 million peak in ALGS by 2030.

ALGS refers to rare genetic condition in which the bile vessels are narrowed, malformed or fewer, leading to excessive bile in the liver. It can cause a variety of symptoms, including cholestatic pruritus.

Mirum obtained exclusive rights to the drug from Shire in 2018. It works by blocking an important protein that transports bile acids.

Livmarli approved information on serious side effects, including liver changes that often signify liver injury or stomach problems.