Janus kinase inhibitors for the treatment of inflammatory bowel diseases: developments from phase I and phase II clinical trials.

INTRODUCTION: A new pharmacological class, Janus kinases (JAK) inhibitors, has been shown to be effective and safe for the treatment of inflammatory bowel diseases (IBDs). The aim of this review is to provide an overview of the JAK inhibitors currently under investigation in phase I and II clinical trials for patients with Crohn's disease and ulcerative colitis and the possible future perspectives for the treatment of IBD patients with this class of drugs. AREAS COVERED: This review describes the JAK-STAT pathway and analyzes the efficacy and safety of new small molecules such as filgotinib, upadacitinib, TD-1473, peficitinib, and Pf-06651600/Pf-06700841, showing data from phase I and II trials. EXPERT OPINION: JAK inhibitors, if approved by the regulatory authorities, could represent a novel and intriguing drug class. In the next years, the approach to patients with IBD will become increasingly personalized.