Rusoritinib phosphate is the phosphate form of Rusoritinib, which is an oral biologic Janus associated kinase (JAK) inhibitor with potential anti-tumor and immunomodulatory activity. Rusoritinib specifically binds and inhibits protein tyrosine kinases JAK 1 and 2, which may lead to a reduction in inflammation and inhibition of cell proliferation. The JAK-STAT (signal transducer and transcriptional activator) pathway plays a crucial role in the signaling of many cytokines and growth factors, and is involved in cell proliferation, growth, hematopoiesis, and immune responses; JAK kinase may be upregulated in inflammatory diseases, myeloproliferative diseases, and various malignant tumors.