Ashraf MikhailRenal Unit, Morriston Hospital, Swansea University, Wales, UKAbstract: Peginesatide is a synthetic, dimeric peptide that is covalently linked to polyethylene glycol (PEG). The amino acid sequence of peginesatide is unrelated to that of erythropoietin (EPO) and is not immunologically cross-reactive with EPO. Peginesatide binds to and activates the human EPO receptor, stimulating the proliferation and differentiation of human red cell precursors in vitro in a manner similar to other EPO-stimulating agents (ESAs). In Phase II and III studies in dialysis and predialysis patients, peginesatide administered once monthly was as effective as epoetin alfa given thrice weekly (dialysis patients) or darbepoetin given once weekly (nondialysis patients), in correcting anemia of chronic kidney disease as well as maintaining hemoglobin within the desired target range. In the dialysis population, the reported side-effect profile of peginesatide was comparable to that known with other marketed ESAs. In the nondialysis studies, compared with those treated with darbepoetin, patients treated with peginesatide experienced a higher adverse-effect profile. Peginesatide is likely to be licensed for treatment of renal anemia in dialysis patients and not in nondialysis patients. Despite this limitation, peginesatide is likely to prove valuable in treating dialysis patients because of its infrequent mode of administration, thereby allowing for a reduced number of injections, with associated better compliance, reduced cold storage requirement, and improved stock accountability. PEGylated therapeutic proteins can elicit immunological response to the PEG moiety of the therapeutic complex. Only long-term experience and post-marketing surveillance will address whether this immunological response will have any impact on the clinical efficacy or safety of peginesatide in clinical practice.Keywords: peginesatide, dialysis, chronic kidney disease