LY2928057, An Antibody Targeting Ferroportin, Is a Potent Inhibitor Of Hepcidin Activity and Increases Iron Mobilization In Normal Cynomolgus Monkeys

Hepcidin, a 25-amino acid peptide hormone which is primarily synthesized and secreted from the liver, is a key regulator of iron homeostasis. It regulates dietary iron absorption, plasma iron concentrations, and tissue iron distribution through interactions with ferroportin, the only known mammalian cellular iron exporter. Hepcidin induces the internalization and subsequent degradation of ferroportin. The reduction in iron release caused by the loss of ferroportin, combined with the continuing demand for iron by erythropoietic precursors, results in a decrease in circulating iron levels. Dysregulation of the hepcidin-ferroportin axis contributes to the pathogenesis of different anemias. Decreased synthesis of hepcidin may cause systemic iron overload in iron-loading anemias such as beta-thalassemia; whereas overproduction of hepcidin may contribute to the development of anemia in inflammatory disorders, malignancies, and chronic kidney disease. LY2928057 is a novel humanized IgG4 monoclonal antibody that binds to human ferroportin with a high affinity, blocks the binding of human hepcidin to ferroportin, and is a potent inhibitor of hepcidin activity in a recombinant ferroportin expressing HEK 293 cell-based assay. In addition, this antibody was able to significantly inhibit hepcidin-induced increase in ferritin levels using Caco-2 cells, a human enterocyte cell line that naturally expresses ferroportin. LY2928057 does not block the efflux of iron from ferroportin, nor does this antibody cause the internalization of this transporter in vitro. Administration of LY2928057 results in a dose dependent increase in serum iron and hepcidin in normal cynomolgus monkeys. LY2928057 may provide therapeutic benefit for patients with hepcidin-related anemia by stabilizing ferroportin located on the cell surface, thus restoring iron export and erythropoiesis. LY2928057 is currently in clinical evaluation.