Filgrastim is a
granulocyte colony-stimulating factor (G-CSF) analog used to stimulate the proliferation and differentiation of
granulocytes; it is a
pharmaceutical analog of naturally occurring G-CSF. It is produced by
recombinant DNA technology. The gene for human granulocyte colony-stimulating factor is inserted into the genetic material of
Escherichia coli. The G-CSF then produced by
E. coli is different from G-CSF naturally made in humans.
Amgen originally licensed filgrastim (trade name Neupogen) in 1991.