Hepcidin as a Predictor of Response to Epoetin Therapy in Anemic Cancer Patients Lidia Ukarma, 1* He ´ le ` ne Johannes, 2 Ulrich Beyer, 1 Michel Zaug, 1 Bruno Osterwalder, 1 and Armin Scherhag 1,3 BACKGROUND: Hepcidin is thought to be the central reg- ulator of iron metabolism. Iron deficiency is associated with low hepcidin concentrations, and anemia in pa- tients with cancer is associated with high concentra- tions of hepcidin. STUDY OBJECTIVES: Our main objective was to assess the potential role of hepcidin for predicting response to epoetin therapy in anemic cancer patients. We also aimed to identify a cutoff value for hepcidin as a poten- tial predictive marker for response to epoetin therapy. METHODS: Using data from 525 anemic cancer patients enrolled in 5 studies, we assessed serum hepcidin con- centrations in 408 of these patients at baseline and an- alyzed pooled data from the 408 patients. The analysis population was separated into 2 categories using a threshold hepcidin concentration of 13 nmol/L: low hepcidin (13 nmol/L) and high hepcidin (13 nmol/L). RESULTS: A significantly higher percentage of respond- ers (defined as hemoglobin increase 10 g/L or 20 g/L from baseline) was observed in the low hepcidin group compared with the high hepcidin group (P = 0.04 for 10 g/L increase and P = 0.009 for 20 g/L from baseline). There was also a statistically significant difference between the 2 groups for hematopoietic re- sponse (hemoglobin rise at least once 20 g/L from baseline or at least once 120 g/L) to epoetin therapy (P = 0.0004). CONCLUSIONS: The results of this analysis suggest a po- tential role of hepcidin serum concentrations in pre- dicting the response to epoetin therapy. © 2009 American Association for Clinical Chemistry Hepcidin (hepatic bactericidal protein) is a peptide of 20, 22, or 25 amino acids, differing by amino-terminal trun- cation. It contains 4 intrachain disulfide bonds and 8 cys- teine residues (1–3 ). The human hepcidin gene consists of 3 exons and 2 introns. The exons encode an 84 –amino acid prepropeptide containing a typical 24 –amino acid leader peptide at the N-terminus, a 35–amino acid prore- gion, and the C-terminal 20 – or 25–amino acid peptide (1 ). Although this peptide was first isolated as a circulat- ing antimicrobial peptide from urine and blood, hepcidin is predominantly expressed and produced by hepatocytes in the liver. Expression is also detectable to a lesser extent in the heart and brain (1 ). Hepcidin enters the circulation and negatively regulates the export of iron in certain cell populations, most importantly in reticuloendothelial (RE) 4 macrophages (an important site of iron storage) and in duodenal enterocytes (site of dietary iron absorp- tion). Hepcidin does so by binding to the cellular iron exporter ferroportin and inducing its internalization and degradation. Iron retention in RE cell populations acutely lowers circulating iron concentration. The iron retention in enterocytes leads to a decrease in dietary iron absorp- tion. Thus, an increase in hepcidin leads to an increase in RE macrophage iron, decreased dietary iron absorption, and decreased circulating iron, all contributing to anemia. These changes in iron metabolism are typically seen in inflammation (4 ). Under conditions of inflammation, physiologic regulation of hepcidin is superseded by the upregulatory effects of certain cytokines, most impor- tantly interleukin-6 (IL-6). Binding of Il-6 to its receptor results in phosphorylation of the intracellular signaling molecule STAT3 (signal transducer and activator of tran- scription 3). Phospho-STAT3 dimerizes and is translo- cated to the nucleus, where it interacts with a character- ized IL-6 response element in the hepcidin promoter (4 ). In oncology patients, anemia of chronic disease due to the underlying cancer is a frequent finding, often aggravated by the myelodepressive effects of chemotherapy. This 1 F. Hoffmann-La Roche Ltd., Basel, Switzerland; 2 DASTA GmbH, Schriesheim, Germany; 3 I. Medical Clinic, University Hospital Mannheim, University of Heidelberg, Germany. * Address correspondence to this author at: F. Hoffmann-La Roche Ltd., Bldg. 682/302, Pharmaceutical Division, PDCA, 4070 Basel, Switzerland. Fax +41-61- 688-31-20; e-mail lidia.ukarma@roche.com. Received December 4, 2008; accepted March 30, 2009. Previously published online at DOI: 10.1373/clinchem.2008.121285 4 Nonstandard abbreviations: RE, reticuloendothelial; IL-6, interleukin-6; STAT3, signal transducer and activator of transcription 3; Hb, hemoglobin; CRP, C-reactive protein. Clinical Chemistry 55:7 1354–1360 (2009) Proteomics and Protein Markers 1354