INCB-028050 phosphate (also known as INCB039110) is a selective Janus kinase 1 (JAK1) inhibitor utilized primarily in medical research and drug development for autoimmune and inflammatory diseases, including rheumatoid arthritis, psoriasis, and ulcerative colitis. It targets the JAK-STAT signaling pathway to modulate cytokine-mediated immune responses, thereby reducing inflammation and disease activity. Clinical trials have evaluated its efficacy, safety, and pharmacokinetics in patients with these conditions. Additionally, ongoing research explores its potential in oncology, such as in combination therapies for hematologic malignancies and solid tumors, due to its role in regulating immune responses and cell proliferation.