BETA - What is stem cell mobilization?

What is stem cell mobilization? So normally our blood does not have too many stem cells. It's less than 1% of stem cells among all of our 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. 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 GCSF or growth factor. It comes in many different ways. The generic version is GCSF, which stands for granulocyte colony stimulating factor. The second most common agent that we use is something called Mosabil or Polarexaphor, which is another agent that cuts the anchors between stem cells in the bone marrow and their 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 aphoresis leads to us having a good amount of stem cells in the blood, and then the aphoresis 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 10 days after the cyclophosphamide for the stem cells to come out because then the bone marrow is regrowing from the insult of the cyclophosphamide. It puts out a lot of stem cells. All of these ways are mobilizing ways of getting stem cells out from the bone marrow into the blood and then the patient undergoes aphoresis, or the collection procedure itself, or harvest sometimes it's called, to collect them and put them in a bag which can then be stored. Yes, so 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 and we called it a bone marrow transplant. But actually now the correct terminology is a hematopoietic stem cell transplant. 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. So we've learned how to stimulate those cells in the bone marrow with these drugs called growth factors or granulite colony stimulating factors or GCSF, also called granics, also called neupogen. These cells will actually lead to the cells to divide and eventually leave the bone marrow. That may be sufficient to actually then start collecting the cells. But in many patients, if you want to collect especially for two transplants, often that's not sufficient and we give a second drug called plurixaphor, 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 the catheter and 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 linolytomide. And transplant physicians were very careful to check that a patient had not received too many months of linolytomide before going on to having stem cell collection. We're now noticing that patients who receive the monoclonal antibodies daratumumab or esatexamab in combination with linolytomide 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 payer issues. It can be performed by the patient. It can be performed by a caregiver. It can be performed at a physician's office. And oftentimes this is related to reimbursements, whether or not the neupogen can be supplied to the patient directly or needs to be administered in the physician's office.