Stem cell transplantation in chronic myeloid leukemia

This review discussed the role of stem cell transplantation in patients with chronic myeloid leukemia.

Stem cell (immature blood cell) transplantation (SCT) has had a long history in the treatment of chronic myeloid leukemia (CML). Patients who have a matched donor (someone who is a close genetic match, such as a sibling) have 85% survival rates following transplantation. The introduction of tyrosine kinase inhibitor (TKI) therapy, such as imatinib (Gleevac), has slowed the use of SCT in chronic phase CML. It is still the preferred treatment for patients with accelerated phase or blast crisis CML, or those who do not respond to TKI therapy.

This review discussed the current practices for SCT in patients with CML.

A recent study examined SCT in patients who progressed after imatinib, chronic phase patients who were at high-risk of progression, or who had accelerated or blast phase (AP/BP) CML. 3-year overall survival (time from treatment until death from any cause) after SCT was 88% in high-risk patients, 94% in those who progressed, and 59% in AP/BP patients. Another study noted a 91% response rate in patients resistant to imatinib.

Studies have suggested that TKI therapy prior to SCT improves outcomes. Chemotherapy treatment before SCT (known as conditioning) is standard. Reducing the intensity of chemotherapy (to decrease the toxic side effects) was not as effective. Intensive conditioning is recommended for all but the oldest patients.

Graft versus host disease (GVHD) in a possible complication of SCT. In GVHD, the donor stem cells attack the organs and tissues of the patient receiving them. Patients should be treated with immune system suppressors to prevent GVHD. TKI therapy has been shown in some studies to reduce the rate of GVHD.

After SCT patients should be monitored for relapse. BCR-ABL (a gene abnormality involved in the development of CML) levels should be monitored, as they can predict relapse.

It is not clear whether patients who have failed two TKI therapies should try a third before SCT. Accelerated phase CML patients are recommended to start a search for a donor. Blast phase CML patients should undergo SCT.

The use of SCT in children is not yet clear. Fertility preservation should be discussed before SCT in both children and adults who still wish to have children.

Future studies may examine whether SCT in patients in remission following TKI therapy may lead to a cure. The use of immunotherapy (treatments that stimulate the immune system to attack the cancer cells) may also be used in combination with SCT.

This study concluded that while therapies are still evolving, SCT may still play an important role in the treatment of CML.