In most cases, chemotherapy, immunotherapy , and/or targeted therapy can reduce the number of leukemia cells in chronic lymphocytic leukemia (CLL) and improve symptoms. These treatments can often control CLL for a long time. But even if all signs of leukemia go away, the disease often comes back later. This is especially true of the types of CLL that are harder to treat , such as those with chromosome 17 deletions and TP53 mutations, as well as CLL that doesn't respond to standard treatments. Higher doses of chemo might work better, but they often can't be used because they could severely damage bone marrow, where new blood cells are made. This could lead to life-threatening infections, bleeding, and other problems linked to low blood cell counts.
A stem cell transplant (SCT) allows doctors to use higher doses of chemo, sometimes along with radiation therapy, to treat CLL. After these treatments, the patient receives a transplant of blood-forming stem cells to restore the bone marrow.
Blood-forming stem cells used for a transplant come either from the blood (for a peripheral blood stem cell transplant, or PBSCT), from the bone marrow (for a bone marrow transplant, or BMT), or from umbilical cord blood. Bone marrow transplant was common in the past, but today it has largely been replaced by PBSCT.
It's not yet clear how helpful stem cell transplants are in patients with CLL. When transplant is done, it's most often as part of a clinical trial.
Types of transplant
The 2 main types of stem cell transplants are allogeneic and autologous.
- For an autologous transplant, the patient’s own stem cells are collected from their blood or bone marrow and then given back after treatment. The problem with this is that leukemia cells may be collected with the stem cells.
- In an allogeneic transplant, the stem cells come from someone else (a donor). To lower the chance of problems, the donor needs to “match” the patient in terms of tissue type. Often, a close relative, like a brother or sister is a good match. Less often, a matched unrelated donor may be found.
Because collecting the patient’s stem cells can also collect leukemia cells, allogeneic transplants are most often used for CLL. This type of transplant can cause severe or even life-threatening complications and side effects, and it's often not a good option in people who are older or have other health problems.