Recent advances in erythropoietic agents in renal anemia.

Red cell production in chronic kidney disease is usually too low to maintain a normal haemoglobin, and thus anaemia develops in a large proportion of patients. The ability to stimulate erythropoiesis in the bone marrow by the use of therapeutic agents has only been possible in the last 20 years, initially with recombinant human erythropoietin (epoetin), and later darbepoetin alfa. Many new agents are, however, in clinical development, and these include CERA, Hematide, and HIF stabilisers, in addition to the imminent launch of biosimilar epoetins. The main issue with biosimilars is the unknown risk of immunogenicity. CERA is a large molecule, approximately twice the size of epoetin, which was created by integrating a single polymer chain into the erythropoietin molecule. CERA has a much prolonged half-life, and Phase II and III clinical trials have investigated administration of CERA every 3 or 4 weeks. Hematide is derived from original research on the erythropoietin-mimetic peptides, and is in Phase II of its clinical trial programme. Again, this compound is being investigated as a once-monthly administration. The HIF stabilizers are orally-active inhibitors of the enzyme that degrades hypoxia-inducible factor (prolyl hydroxylase), and this leads to upregulation of erythropoietin gene expression. Other strategies for stimulating erythropoiesis, briefly described in this review, are at an earlier stage of development. This is an exciting and rapidly developing area of scientific and translational research.