What is stem cell mobilization?

What is stem cell mobilization?

So I'm normally our blood does not have too many stem cells. It's less than 1% of stem cells among all of our like white blood cells. So to collect enough stem cells to do a stem cell transplant, we need to boost the number of stem cells in the blood. And then these stem cells have to come out of the bone marrow into the peripheral blood. And for that, we use agents that boost those stem cells. These agents are called mobilizing agents. The most common mobilizing agent these days is neupogen or G-CSF for growth factor comes in very many different ways. The generic version is G-CSF that stands for granulocyte colony stimulating factor. The second most common agent that we use is something called mozobil or plerixafor, which is another agent that cuts the anchors between stem cells in the bone marrow and that environment. So the stem cells are then free to come out of the bone marrow into the blood. The use of these agents for about three or four days prior to the date of apheresis leads to us having a good amount of stem cells in the blood, and then the apheresis is becoming a short procedure. It only takes one or two days. In that case. Another way of doing this, or the conventional old way of doing this was to give a person a chemotherapy called cyclophosphamide and then wait for about ten days after the cyclophosphamide for the stem cells to come out, because then the bone marrow is regrowing from the insult of cyclophosphamide. It puts out a lot of stem cells. So all of these ways are mobilizing ways of getting stem cells out from the bone marrow into the blood, and then the patient undergoes apheresis or the collection procedure itself are harvested. Sometimes it's called to collect them and put them in a bag which can then be stored. In the old days of the bone marrow transplantation, we actually did go to the operating room and take a liter of your bone marrow. Then we would do the chemotherapy and give you back your bone marrow. We called it a bone marrow transplant. But actually now, the correct terminology is the hematopoietic stem cell transplant. And the reason for that is that we learned that we don't need the entire bone marrow to restore your bone marrow. We actually just need the stem cells to live in your bone marrow. And so we've learned how to stimulate those cells in the bone marrow with these drugs called growth factors or granulocyte colony stimulating factors or G-CSF, also called granix, also called neupogen. These cells will actually lead to the cells to divide and eventually leave the bone marrow, and that may be sufficient to actually then start collecting the cells. But in many patients, if we want to collect, especially for two transplants, often that's not sufficient and we give a second drug. Plerixafor, which actually basically removes the anchor of the stem cells in the bone marrow and allows them to float away into the blood. And so we're basically pushing the cells out into the bloodstream so that we can then collect them through a catheter, through the peripheral blood. Are there any induction therapies that can make stem cell mobilization harder to happen? We've learned that some of our excellent, excellent induction therapies that produce really good results actually do make it a little bit more difficult to collect the stem cells. For a long time, the real culprit was the lenalidomide. And transplant physicians were very careful to check that a patient had not received too many months of lenalidomide right before going on to having stem cell collection. We're now noticing that patients who receive the monoclonal antibodies, daratumumab or isatuximab in combination with lenalidomide also sometimes have difficulty mobilizing. And so it's something that we can usually work around and still get an adequate stem cell collection after those treatments. But we do keep track of how much treatment someone has had.

Who administers growth factor shots?

So that actually depends on payor issues. It can be performed by the patient. It can be performed by a caregiver. It can be performed at physician's office. And oftentimes, this is related to reimbursements, whether or not the neupogen can be supplied for the patient directly or needs to be administered in a patient in the physician's office.