Technique May Allow Half-matched Donors in Stem Cell Transplants

A new technique appears to make possible half-matched donors for patients with pediatric acute leukemia – possibly marking a significant step forward in the treatment of these patients.

According to a presentation by Alice Bertaina, M.D., of Bambino Gesu Children's Hospital in Rome, patients needing a stem cell transplantation for acute leukemia may no longer have to wait to find a matched donor. Their parents, each a half-matched donor, may be able to be effective donors.

And this is possible without reducing survival rates.

A new technique

Previously, half-matched donors have met with little success and high rates of infection as well as recurrence of disease. However, Bertaina and colleagues used a technique to physically remove what she called the “bad” cells from the graft by using magnetic beads to draw out a subset of cells involved in causing graft-versus-host disease (GVHD), the so-called alpha/beta-positive T cells and CD19-positive B cells.

What is left behind are largely gamma/delta-positive T cells and natural killer cells. These cells, they found, engraft easily and with low rates of relapse and mortality.

High survival rates

Their study involved 50 children whose parents each donated stem cells. After 35 months, the total incidence of relapse was 19 percent (two patients died), allowing for a leukemia-free survival rate of 77 percent – very comparable to the figures from fully matched transplants.

No cases of stomach or liver acute GVHD developed. However, 13 patients did develop skin-only GVHD of grades I and II, she said.

On top of that, it didn’t matter which parent donated the stem cells.

Source: ASH 2013