fzj-003

FZJ-003 is an orally administered, selective Janus kinase 1 (JAK1) inhibitor developed as a small molecule drug for the treatment of autoimmune diseases, particularly rheumatoid arthritis, atopic dermatitis, and ulcerative colitis. It is structurally modified from filgotinib to enhance selectivity and pharmacokinetic properties. Preclinical studies indicate that FZJ-003 has higher systemic exposure and lower clearance compared to filgotinib. The drug acts by inhibiting JAK1-mediated cytokine signaling pathways involved in immune responses. Developed by Shanghai Fudan-Zhangjiang Bio-Pharmaceutical, it has completed phase I clinical trials in China for autoimmune disorders and received regulatory acceptance for phase II trials in atopic dermatitis and ulcerative colitis[1][2][3][4][5][7].