What are growth factors?

What are growth factors, when are they given and what is the dosing?

So growth factors are frequently employed in the care of multiple myeloma. We do have the GCSF, granulocyte stimulating factor which boosts the type of white blood cell called neutrophil. This is the main white blood cell that helps us fight bacterial infections. As as far as how frequently to use, we would dose the drug based on the number of neutrophil count. When the neutrophil counts are low, the growth factor can be given to boost and prevent severe infections, and these can be done weekly or right after the chemotherapy or as needed. I should mention that this growth factor called GCSF is also commonly given right before the stem cell collection in order to boost the white cells. So that we are able to collect the stem cells for future transplant.

Growth factors are synthetic or mimic these normal chemicals that are released by various cells in the body to help stimulate growth of white cells. So we have commercially available growth factors for that. There have been growth factors for red cells that don't get used very much in myeloma anymore. And then there are some newer agents that can help stimulate platelets. And again, those have not really been well-studied in myeloma at this point.

So primarily what we're talking about when we say growth factors are things that boost a white cell count and specifically in neutrophil count. Now, in terms of growth factors, I think that they definitely have a role. Certainly the kind of chemotherapy that we give that has maybe three or four drugs, higher likelihood of having a low white count that is becoming neutropenic, so often we are asking patients to use growth factors intermittently.

A little bit of a controversy about growth factor use after CAR-T. I think that's probably going to be studied a little bit more with more discussion. But in particular, patients after CAR-T transplants can have very low white counts for weeks and even months sometimes. And I think particularly in that situation, a lot of people are getting more comfortable saying, well, we're going to put you on filgrastim or GCSF, something like that, to try to help boost your count. And certainly in those kinds of therapies, people are always on prophylactic, usually antiviral, antifungal and often antibacterial as well.