LY2784544 is a potent and selective inhibitor of JAK2 (Janus kinase 2), particularly effective against the JAK2V617F mutant form commonly associated with myeloproliferative neoplasms (MPNs). It has been investigated for the treatment of hematologic malignancies such as myelofibrosis, polycythemia vera, and essential thrombocythemia, where dysregulated JAK-STAT signaling drives disease progression. By inhibiting JAK2 phosphorylation and downstream signaling, LY2784544 reduces cytokine-driven cell proliferation and inflammation, leading to improvements in splenomegaly, constitutional symptoms, and blood cell counts in clinical studies. Its selectivity profile may offer a favorable safety window compared to broader JAK inhibitors, potentially reducing off-target effects such as immunosuppression. Research continues to explore its role in combination therapies and in patients resistant to other JAK inhibitors.