In Vitro and In Vivo Assays for High-Molecular-Weight Pegylated Muteins of Granulocyte Colony-Stimulating Factor

The hematopoietic growth factor granulocyte colony-stimulating factor (G-CSF) has been in the clinic since 1986, when the clinical development of bacterially synthesized recombinant filgrastim began (1 ). A glycosylated form of G-CSF (lenograstim) has been approved for use in Europe and a bacterial recombinant mutein (nartograstim) has been approved in Japan. All forms of G-CSF are now commonly used for many types of neutropenia, including that resulting from anticancer therapies.