LAUSR

We thank Drs. Chen and Vitetta for their letter regarding our manuscript describing our phase 2 study of the nonsteroidal farnesoid X receptor (FXR) agonist cilofexor in non-cirrhotic patients with primary sclerosing cholangitis (PSC).1 As the authors point out, decreased levels of certain bile acid species secondary to FXR agonism could in theory worsen the colitis commonly associated with PSC. They propose that these deleterious effects could be mitigated by the addition of butyrate, a short chain fatty acid that serves as a key fuel source for colonic epithelial cells and is used as therapy in disorders such as diversion colitis.