AGEM400(HES), a Novel Erythropoietin Mimetic Peptide Conjugated to Hydroxyethyl Starch with Excellent In Vitro Efficacy

We developed and tested a compound called AGEM400(HES) that consists of a novel erythropoietin mimetic peptide (EMP) which is produced as a continuous N- to C-linked dimer and is conjugated to biodegradable hydroxyethyl starch (HES). In various in vitro assays, AGEM400(HES) demonstrated excellent efficacy, better than the peptide alone, and comparable to the efficacy of erythropoietin (EPO) and Aranesp (Darbepoietin alpha). The assays included survival assays on EPO-responsive cell lines (EC50 below 1 ng/ml peptide) and clonogenic assays on human bone marrow cells (EC50 1 to 10 ng/ml). AGEM400(HES) caused phosphorylation of STAT5 and ERK signalling proteins in UT7/EPO cells in a similar fashion as EPO. AGEM400(HES) replaced EPO from its receptor and the in vitro activity of AGEM400 (HES) was inhibited by soluble EPO receptor. Antibodies generated in mice and rabbits against EPO did not recognize AGEM400(HES) peptide, and vice versa. A sensitive ELISA was able to detect AGEM400(HES) at low nanogram per ml concentrations which allows for bioanalytics of AGEM400(HES) serum levels in future in vivo studies. As a result, AGEM400(HES) is a promising drug candidate for anemias related to renal insufficiency and/or in oncological settings.