Is mismatched donor stem cell transplantation an effective treatment in high-risk relapse of ALL?

This study looked at the effectiveness of mismatched donor stem cell transplantation (SCT) for treating children with high-risk relapse of acute lymphoblastic leukemia (ALL). Researchers found that mismatched donor SCT was useful but not as effective as matched donor SCT in children with high-risk ALL.

Acute lymphoblastic leukemia is a cancer of the bone marrow which affects the white blood cells of the immune system. A stem cell transplantation is a common treatment option. Donor stem cells can be a genetic match to the patient (such as from a sibling) but this is not always available. Donor stem cell can also be mismatched but this is not always successful. ALL often has a high risk of relapse (disease coming back) after treatment. It is important to research how effective mismatched donor SCT is in the treatment of high-risk relapse ALL.

1115 patients were included in the study. 148 patients received mismatched donor SCT. Of these, 42 (28.3%) were considered high-relapse risk and 106 (71.7%) were very high-relapse risk. Donor stem cells came from bone marrow, umbilical cord, or other immune cells. Patients were followed for an average of 5.1 years.

Of the patients with mismatched donors, 56% survived overall after 4 years and 52% had survived event-free (no relapse of disease) after 4 years. 82% of high-relapse risk patients transplanted from mismatched donors survived overall after 4 years and 80% were event-free. Very high relapse risk patients had an overall survival rate of 45% and event-free survival of 42% after 4 years. 29% of patients had a relapse of disease. 19% of patients died without a relapse of disease.

Of the 120 patients living after 100 days, 15% experienced severe graft-versus-host disease (when the transplanted cells attack healthy tissue).

The study concluded that mismatched SCT treatment was useful but less effective than matched SCT treatment for high-relapse risk ALL.