In 2006, Takeda Pharmaceutical Co. Ltd. and Affymax Inc. signed a pair of partnerships to combine the resources and access of a Japanese pharma with the innovation of a U.S. biotech in order to exploit market opportunities in Asia and the West.

The deals were built around Affymax's peginesatide, a pegylated synthetic peptide-based erythropoiesis-stimulating agent that the companies expected to offer efficacy and safety similar to marketed ESAs with the added benefit of less frequent dosing and consequent cost savings.