You’ve been selected as a peripheral blood stem cell donor and confirmed as the best possible match for your patient. The next steps involve preparing for your collection, including injections with something called “filgrastim.” Some of the first questions Gift of Life's donor coordinators hear are "what is it?" and "is it safe?"
Filgrastim is a man-made form of a hormone produced in the body called granulocyte-colony stimulating factor (G-CSF), which stimulates the bone marrow to produce more blood cells. Filgrastim is used in cancer patients to help treat neutropenia, a low white blood cell count, in individuals who have received high doses of radiation, and in healthy individuals prior to a peripheral blood stem cell (PBSC) transplant. This use before PBSC collection makes it easier to collect enough blood stem cells from donors through apheresis.
The production and release of functional neutrophils, a type of white blood cell, from the bone marrow are normally regulated by G-CSF. G-CSF acts on the hematopoietic cells, also known as blood stem cells, by binding to the cell’s surface to stimulate the proliferation (reproduction and expansion), differentiation (change in function), and maturation (development into a final functioning cell) of neutrophil precursors. Filgrastim mimics the biological actions of the G-CSF naturally produced by the body to increase these effects.
What does that all mean? In short, filgrastim signals your bone marrow to create more blood stem cells. Filgrastim also facilitates the release of blood stem cells from the bone marrow into the circulating blood, making more stem cells available for collection via the apheresis process.
“When you get filgrastim, it works like your body’s natural hormone,” says Dr. Bruce Lenes, M.D., Gift of Life Marrow Registry’s Co-Chief Medical Officer. “It boosts your white blood cells and helps move stem cells from your bone marrow into your blood. Then, the stem cells can be collected using an apheresis machine, similar to how plasma is collected in blood banks."
Filgrastim and other bio-similar medicines were first identified in 1984 and have been FDA-approved since 1991 after years of clinical trials. Since then, G-CSF has gone on to help millions of patients and stem cell donors.
The National Institutes of Health (NIH) describes its short-term use, as in PBSC donation, as having “a high margin of safety.”
“Yes, filgrastim is safe, but not without its side effects,” said Dr. Lenes. “Donors taking filgastrim often experience bone pain and mild flu-like symptoms. More severe side effects are extremely uncommon. It has been used safely for decades, and it has been given to millions of patients and donors since its FDA approval.” He continued, “almost all donors who receive filgrastim during their donation say they would do it again in a heartbeat."
While some donors experience no symptoms from filgrastim use, others report that over-the-counter pain relievers like Tylenol are sufficient to help with the mild achiness it can cause. This feeling typically disappears within a day of the final filgrastim injection, and sometimes within a few hours of donation. Every person has a different experience with its use, but almost all donors recover within 24 – 48 hours from the PBSC donation process.
Gift of Life donors receive daily injections of filgrastim for five consecutive days leading up to their PBSC donation. Here is a breakdown of the injection schedule:
All injections are given subcutaneously, typically in the fatty tissue of the upper arms, thighs, or abdomen, using a small-gauge needle. The dose is weight-based and prescribed by a Gift of Life medical provider. Before each injection, a nurse reviews the donor’s vitals and screens for any symptoms or concerns. Depending on the prescribed dose, some donors may receive more than one injection per day to ensure the full amount is administered.
If you’re preparing to donate and have specific questions, please speak to your donor services coordinator, who can help arrange a conversation with our medical team. You can also ask your personal doctor for their opinion.
If you’re a registry member and hope to donate someday, once you are identified as a match and are ready to move forward, you’ll have a comprehensive information session to explain the entire donation process.
Thank you for being a Gift of Life donor! Without heroes like you, we wouldn’t be able to fulfill our lifesaving mission.
Not a donor yet? Order a cheek swab kit here for your chance to save someone's life!
NIH National Library of Medicine: https://pmc.ncbi.nlm.nih.gov/articles/PMC7122905/
NIH National Library of Medicine: https://pubmed.ncbi.nlm.nih.gov/39158170/
CDC https://www.cdc.gov/radiation-emergencies/hcp/clinical-care/neupogen.html
Mayo Clinic https://www.mayoclinic.org/drugs-supplements/tbo-filgrastim-subcutaneous-route/description/drg-20061234
Medicine Plus https://medlineplus.gov/druginfo/meds/a692033.html
Neupogenhcp https://www.neupogenhcp.com/important-safety-information