Since the 1990's, cheating athletes have abused substances to increase their 
oxygen transport capabilities; among these substances, recombinant EPO is the 
most well known. Currently, other investigational pharmaceutical products are 
able to produce an effect similar to EPO but without having chemical structures 
related to EPO; these are the synthetic erythropoiesis stimulating agents 
(ESAs). Peginesatide (also known as Hematide™) is being developed by Affymax and 
Takeda and, if approved by regulatory authorities, could soon be released on the 
international market. To detect potential athletic abuse of this product and 
deter athletes who consider cheating, we initiated a collaboration to implement 
a detection test for anti-doping purposes. Peginesatide is a synthetic, 
PEGylated, investigational, peptide-based erythropoiesis-stimulating agent that 
is designed and engineered to stimulate specifically the erythropoietin receptor 
dimer that governs erythropoiesis. It is undetectable using current anti-doping 
tests due to its lack of sequence homology to EPO. To detect and deter potential 
abuse of peginesatide, we initiated an industry/antidoping laboratory 
collaboration to develop and validate screening and confirmation assays so that 
they would be available before peginesatide reaches the market. We describe a 
screening ELISA and a confirmation assay consisting of immune-purification 
followed by separation with SDS-PAGE and revelation with Western double 
blotting. Both assays can detect 0.5 ng/mL concentrations of peginesatide in 
blood samples, enabling detection for several days after administration of a 
physiologically relevant dose. This initial report describes experimental 
characterization of these assays, including testing with a blinded set of 
samples from a clinical study conducted in healthy volunteers.