Tyk2-IN-4, also known as BMS986165, is primarily used in the treatment of autoimmune diseases such as psoriasis. It functions as a selective inhibitor of Tyk2 (Tyrosine kinase 2), which plays a crucial role in the signaling pathways of cytokines involved in immune responses. By inhibiting Tyk2, this compound helps to reduce inflammation and the overactive immune response that characterizes autoimmune conditions. Clinical trials have demonstrated its efficacy in improving skin lesions and overall disease severity in patients with moderate to severe plaque psoriasis. Additionally, its targeted mechanism of action offers a potentially safer profile with fewer side effects compared to broader immunosuppressive therapies. Ongoing research is exploring its application in other autoimmune disorders, including lupus and inflammatory bowel disease.