Catholic University Catholic Hematology Hospital

What is autologous hematopoietic stem cell transplantation?

This treatment approach involves giving a dose of chemotherapy that's three to ten times higher than usual to maximize the destruction of cancer cells. After this high-dose chemotherapy, the patient's own hematopoietic stem cells are used to help restore the function of the bone marrow, which gets damaged by the intense chemotherapy. These stem cells are usually collected from the patient's peripheral blood before the chemotherapy begins, and they are cryopreserved, or frozen, for later use. Once the high-dose chemotherapy is completed, these preserved cells are returned to the patient's body to help rebuild the bone marrow and restore its function.

In cases of Wilms' tumor, when is autologous stem cell transplantation performed?

When it comes to Wilms' tumor, a kidney cancer often found in children, 90% of cases have what we call a "favorable histology." This means that the cancer cells look a lot like normal kidney cells and usually respond well to treatment. But, the other 10% are made up of tougher types like anaplastic Wilms' tumor, clear cell sarcoma of the kidney, and rhabdoid tumor. These types are more resistant to treatment and are often responsible when treatments don't work. For these stubborn types of Wilms' tumor, we might need to bring out the big guns. This could include high-dose chemotherapy, which uses larger amounts of chemotherapy drugs than usual to try to kill off more cancer cells. But these high doses can also harm the healthy cells in your bone marrow, where your body makes new blood cells. To help your body bounce back from this high-dose chemotherapy, we might do a procedure called autologous hematopoietic stem cell transplantation. This means we take some of your own stem cells before the chemotherapy, and then put them back into your body after treatment. This helps your bone marrow recover and start making healthy blood cells again.
If the Wilms' tumor comes back, or recurs, we turn to something called salvage chemotherapy. This is a type of chemotherapy we use when the usual treatment hasn't worked. After this, we might follow the same steps as with the tougher types of Wilms' tumor: high-dose chemotherapy and autologous hematopoietic stem cell transplantation to help your bone marrow get back to normal.

What is the process for collecting autologous hematopoietic stem cells?

In order to collect enough of your own hematopoietic stem cells for a transplant, we need to nudge them out of your bone marrow and into your bloodstream. We usually do this using certain drugs, either chemotherapy or hematopoietic growth factors, which help stimulate your bone marrow to produce more of these stem cells and release them into your blood. Most patients have this stem cell collection procedure after they've finished a round of chemotherapy, like salvage therapy. We wait until tests show that there are no more cancer cells in your bone marrow, and your white blood cell counts start to go back up. The collection procedure itself is done in a special unit called an apheresis unit. You'll be hooked up to a machine that collects your blood, separates out the stem cells, and returns the rest of your blood back to your body. Each session usually lasts about 4-5 hours. Depending on how quickly your body is able to produce and release these stem cells, the collection might take as little as one day or as much as two to three days. We keep going until we've collected enough stem cells for your transplant. After we've collected enough stem cells, we'll freeze them until your transplant day. This is called cryopreservation, and it keeps your stem cells safe and viable until we're ready to put them back into your body.

What are the preparatory steps before autologous stem cell transplantation?

Transplantation is a complex process that involves high doses of chemotherapy or radiation, various medications and fluids, and numerous blood transfusions. Because of the intensity of these procedures, they can sometimes lead to significant complications related to the transplant. It's very important that a patient is physically strong enough to go through this process. That's why we conduct thorough pre-transplant evaluations. These evaluations give us a clear picture of the patient's disease status and overall health, and help us make sure the patient is physically capable of undergoing the transplant. Part of this evaluation includes consultations with specialists in dental and ear, nose, and throat (ENT) care. The goal here is to identify and treat any potential infections before they can complicate the transplant process. We also use diagnostic tests, like pulmonary function tests and echocardiograms, to assess how well essential organs are working. On top of that, we conduct serological and urine tests for infections to get a complete understanding of the patient's health. All of these steps help us evaluate the patient's condition before we go ahead with the hematopoietic stem cell transplantation. We want to make sure we're giving the patient the best chance for a successful transplant.