Uses for Recombinant Protein Drugs - Biotechnology and Your Health: Pharmaceutical Applications - page 73

patients (Procrit) and patients with kidney failure (Epogen). To
produce darbepoietin (Aranesp), a sweetened form of erythro-
poietin, scientists changed the gene sequence so that the protein
has two more places to which the producing animal cell would
automatically attach chains of sugars. The added sugars make
Aranesp stay in the blood two to three times longer than Epogen
or Procrit so that it can be injected once a week rather than two or
three times a week.
Helping the Body Fight Infection
Three recombinant protein drugs—Leukine ® , Neupogen ® , and
Neulasta ® —are used to stimulate the formation of infection-
fighting white blood cells in patients undergoing chemotherapy for
cancer treatment. The goal is to make sure patients have enough
white blood cells to attack infecting bacteria. Several different
types of infection-fighting white blood cells come from one pre-
cursor cell, and sargramostim (Leukine) stimulates the production
of the shared precursor. Produced in yeast cells, sargramostim
differs from the native form of the protein by one amino acid.
Filgrastim (Neupogen) and pegfilgrastim (Neulasta) are two forms
of a natural protein that stimulates production of infection-fighting
white cells at the last step. Both are produced in E. coli , but peg-
filgrastim is tagged with polyethylene glycol, making it stay in
the blood five times longer or even more, thus allowing a more
convenient schedule of injections.
Platelets , small cell fragments produced from bone marrow
cells, work with the cascade of proteins in the formation of blood
clots. If platelet counts are low, leaks in blood vessels that would
normally be small can lead to the loss of large amounts of blood.
Certain chemotherapy drugs knock out the production of the
cells that produce platelets. Oprelvekin (Neumega ® ), produced in
E. coli , stimulates bone marrow to produce that very important
type of cell.