Abstract: The present application relates to an anti-Nectin-4 antibody, a drug conjugate and a preparation method and use thereof, which can be effectively used for the treatment and/or prevention of Nectin-4 positive tumors, including cancers, such as breast cancer and bladder cancer.

Abstract: The present application provides use of Compound (I), an optical isomer thereof or a pharmaceutically acceptable salt thereof in manufacture of a medicament useful in treating a disease related to high expression or abnormal activation of JAK and SYK kinases, comprising an autoimmune disease, such as an immune-mediated skin disease, in particular psoriasis, atopic dermatitis and SLE. Compound (I), an optical isomer thereof or a pharmaceutically acceptable salt thereof according to the present invention can improve the skin lesions in mice with psoriasis, atopic dermatitis and SLE, alleviate the injury of kidney, inhibit the expansion of immune organs, reduce the level of inflammation, inhibit the increase of SLE related antibodies and cytokines in serum, and has a certain safe therapeutic window, which has a good clinical application prospect.