Does graft versus host disease affect relapse and survival rates after a stem cell transplant in childhood leukemia?

This study examined the effect of graft versus host disease on relapse rates in children with acute leukemia. This study concluded that graft versus host disease may protect against relapse, but they did not see an effect on survival.

One complication following an allogeneic stem cell transplant (transplant using donor cells) is graft versus host disease (GVHD). In GVHD, types of white blood cells (the T cells) from the donor begin attacking the healthy cells of the body. The risk of GVHD can be lowered by matching the donor cells to that of the patient as closely as possible. However, the T cells activated in GVHD may also attack remaining cancer cells, lowering the risk of relapse. The effect of GVHD on relapse is still under investigation.

This study included 1526 children with either acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL). All the children in the study received their bone marrow transplant after their first or second complete remission. 

Overall, 20.1% of patients relapsed. Three-year overall survival (OS; time from treatment until death from any cause) was 75.8%. Non-relapse mortality (death due to a cause other than disease relapse) was  9.1%.

42.7% of patients developed acute GVHD (aGVHD, occurring within 100 days of transplant). For patients with mild to moderate aGVHD (grades 0 to 1), relapse rates were 24.3% to 25.4%. 18.9% of patients with moderate (grade 2) aGVHD relapsed. The rate was 21.2% for grade 3 and 20% for grade 4 aGVHD.

3-year OS for grades 0 to 2 aGVHD was 76.3% to 79.5%. OS was 66.9% for grade 3 and 42.5% for grade 4 aGVHD.

Chronic GVHD (occurring after 100 days) also showed a reduced relapse rate but with no survival advantage.

ALL was more sensitive to aGVHD, while AML was more sensitive to cGVHD.

This study concluded that GVHD in children with acute leukemia may prevent against relapse, but did not improve survival.