How does filgrastim work?
Filgrastim is designed to lower risk of infection after chemotherapy. It is part of a family of drugs called “granulocyte colony-stimulating factor” (G-CSF), or growth factor.
Filgrastim binds to bone marrow stem cells to speed up production of certain white blood cells known as neutrophils. Neutrophil white blood cells are part of your immune system. Chemotherapy kills fast growing cells such as cancer cells, but sometimes kills good cells such as neutrophils too. When this happens, it is called neutropenia, a sign that your immune system is weakened and low in neutrophils.
Neutrophils are some of the first responders to infection. In a normal immune system, neutrophils cause swelling, redness, and itching at the site of infection. After chemotherapy, neutrophils die and do not cause the same symptoms of infection. Fever may be one of the only signs of infection.
When neutrophils become low and you have a fever, it is called neutropenic fever. Neutropenic fever is a medical emergency. Fevers after chemotherapy should be reported to a doctor immediately or patients should report to a hospital emergency department.
Goals of therapy:
Filgrastim is used to keep the neutrophil count from declining to unsafe levels after certain chemotherapy regimens are given, specifically those having a high risk of neutropenic fever. This lowers the risk of neutropenic fever, but does not prevent it all of the time.
When filgrastim is taken to prevent neutropenic fever, it is known as prophylaxis, or prophylactic therapy. On occasion, filgrastim is given as prophylaxis to patients who have a low neutrophil count from reasons other than chemotherapy. If you develop neutropenic fever, filgrastim may also be used to help treat neutropenic fever in certain situations.
Filgrastim is also used for those undergoing a stem cell transplant, commonly known as a “bone marrow transplant” (BMT). Filgrastim is used to produce the extra stem cells needed for collection before transplant. It may also be used at least 24 hours after certain types of transplants to help increase the likelihood of engraftment.