Bone marrow or peripheral blood stem cell transplant for acute lymphocytic leukemia

While very high doses of chemotherapy (chemo) drugs might work better to kill acute lymphocytic leukemia (ALL) cells, they can cause severe damage to bone marrow cells, which could be life-threatening. Stem cell transplants (SCT) offer a way for doctors to use high doses of chemo. Although the drugs destroy the patient's bone marrow, transplanted stem cells can restore the bone marrow's ability to make blood.

Stem cells for a transplant come from either the blood or from the bone marrow. Bone marrow transplants were more common in the past, but they have largely been replaced by peripheral blood stem cell transplant (PBSCT).

Types of transplants

The stem cells can come from either the patient (an autologous transplant) or from a matched donor (an allogeneic transplant). There is a good reason to use stem cells from someone else for the transplant. These cells seem to help fight any remaining leukemia cells through an immune reaction. This is called a graft-versus-leukemia reaction.

Allogeneic stem cell transplant: In an allogeneic transplant, the stem cells come from someone else – usually a donor whose tissue type is a very close match to the patient's. The donor may be a brother or sister if they are a good match. Less often, an unrelated donor may be found. An allogeneic transplant is the preferred type of transplant for ALL when it is available.

"Mini-transplant": Some patients over the age of 55 might not be able to have a regular transplant that uses high doses of chemo. But some may be able to have what is called a "mini-transplant" (also called a non-myeloablative transplant or reduced-intensity transplant), where they get lower doses of chemo and radiation that do not destroy all the cells in their bone marrow. They then are given the donor stem cells. These cells enter the body and form a new immune system, which sees the leukemia cells as foreign and attacks them (a graft-versus-leukemia effect). This is not a standard treatment for ALL, and is being studied to find out how useful it may be.

Autologous stem cell transplant: In an autologous transplant, a patient's own stem cells are removed from his or her bone marrow or blood. They are frozen and stored while the person gets treatment (high-dose chemo and/or radiation). The stem cells are then given back to the patient after treatment.

One problem with autologous transplants is that it is hard to separate normal stem cells from leukemia cells in the bone marrow or blood samples. Even after treating the stem cells in the lab to try to kill or remove any leukemia cells, there is the risk of returning some leukemia cells with the stem cell transplant.

The transplant process

The transplant process works like this: stem cells are collected from the bloodstream or bone marrow and are frozen and stored. The patient is then given very high doses of chemo while in in the hospital to kill the cancer cells. The patient may also get total body radiation to kill any cancer cells that the chemo might miss. After treatment, the stored stem cells are given to the patient as a blood transfusion. The stem cells settle into the patient's bone marrow over the next several days and start to grow and make new blood cells.

People who get a donor's stem cells are given drugs to prevent rejection as well as other medicines if needed to prevent infections. Usually within a couple of weeks after the stem cells are given, they start making new white blood cells. Then they begin making platelets, and finally, red blood cells.

Patients having SCT have to be kept away from germs as much as possible until their white blood cell count is at a safe level. They are kept in the hospital until part of the white cell count called the ANC reaches a certain number, usually around 1,000. After they go home, they will be seen in the outpatient clinic almost every day for several weeks. After that, they may make regular visits to the outpatient clinic for about 6 months, then their care may be given by their regular doctors.

Some things to keep in mind

A stem cell transplant is a complex treatment that can cause life-threatening side effects. If the doctors think that a person with leukemia might be helped by this treatment, it is important that it be done at a hospital where the staff has experience with the procedure. Some transplant programs may not have experience in certain transplants, especially those from unrelated or mismatched donors.

Stem cell transplant costs a lot, often well over $100,000. It may involve a long hospital stay. Because some insurance companies see it as an experimental treatment, they might not pay for it. Even if the transplant is covered by your insurance, your co-pays or other costs could easily amount to tens of thousands of dollars. It is important to find out what your insurer will cover and what you might have to pay before deciding to have a transplant.

Side effects of stem cell transplant

Side effects from stem cell transplant can be divided into early and long-term effects.

Early side effects: Early side effects are much the same as those caused by any other type of high-dose chemo, such as nausea, vomiting, loss of appetite, mouth sores, and hair loss. Because of the high doses of chemo used, these can sometimes be severe.

One of the most common and serious short-term effects is the greater risk of infection. Antibiotics are often given to try to prevent these infections. Other side effects, like low red blood cell and platelet counts, may mean the patient will need transfusions.

A rare but serious side effect of stem cell transplant is called veno-occlusive disease of the liver (VOD). In this disease, the high doses of chemo given for the transplant damage the liver. Symptoms include weight gain (from fluid collecting), liver swelling, and yellowing of the skin and eyes (jaundice). When severe, it can lead to liver failure, kidney failure, and even death.

Long-term side effects: Some side effects can last for a long time, or may not happen until years after the transplant. These long-term side effects can include the following:

• Graft-versus-host disease (GVHD), which occurs only in a donor transplant (see below)
• Damage to the lungs, causing shortness of breath
• Damage to the ovaries causing infertility and the loss of menstrual periods
• Damage to the thyroid gland that causes problems with changing food into energy
• Damage to the eye that can affect vision (cataracts)
• Bone damage (If damage is severe, the patient may need to have part of the bone and joint replaced.)
• Development of another leukemia (or other type of cancer) several years later

Graft-versus-host disease (GVHD) is one of the main problems of a donor stem cell transplant. It happens when the patient's immune system is taken over by that of the donor. The donor immune system then starts to attack the patient's other tissues and organs.

Symptoms can include severe skin rashes with itching and severe diarrhea. The liver and lungs may also be damaged. The patient may also become tired and have aching muscles. If bad enough, the disease can be fatal. Drugs that weaken the immune system may be given to try to control GVHD. On the plus side, this disease may also cause any remaining leukemia cells to be killed by the donor immune system.

To learn more about stem cell transplants, see our document, Stem Cell Transplant (Peripheral Blood, Bone Marrow, and Cord Blood Transplants).