JAK1 and autoimmune disease: <h4>Introduction</h4>This clinical trial aimed to assess the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of LW402, a preferential JAK1 inhibitor, in healthy participants, so as to provide support for its further development in treating autoimmune diseases.<h4>Methods</h4>The study included two phases: a single ascending dose (10-400 mg) with 54 participants and a multiple ascending dose (50-150 mg, b.i.d for 6 days plus a single dose on day 7) with 36 participants.