Younger Mismatched Donors Bring New Hope for Blood Cancer

New research suggests that younger mismatched stem cell donors could expand transplant options for blood cancer patients who cannot find closely matched donors. Findings from the ACCESS trial indicate that carefully selected younger unrelated donors with greater genetic mismatches can still deliver encouraging outcomes when modern transplant methods are used.

The study, published in Blood Advances, analyzed 268 adults with blood cancers who underwent allogeneic hematopoietic cell transplantation using peripheral blood stem cells from mismatched unrelated donors. All patients received post-transplant cyclophosphamide (PTCy), a treatment used to reduce the risk of graft-versus-host disease (GVHD), a potentially serious complication in which donor immune cells attack the recipient's tissues.

Researchers found that patients receiving more mismatched donor grafts had encouraging results. One year after transplantation, overall survival was 85.6% among recipients of more mismatched grafts, compared with 78.6% among those receiving 7/8 matched grafts. Severe acute and chronic GVHD, relapse and non-relapse mortality rates also remained favorable.

The findings challenge the traditional emphasis on finding the closest possible HLA match and suggest that donor age and other characteristics may also play an important role in transplant success. In the ACCESS trial, donors were between 18 and 35 years old, allowing researchers to assess outcomes using a uniformly younger donor population.

While the researchers stress that the analysis was exploratory and requires longer follow-up, the results indicate that selected younger mismatched donors could be a viable option when closely matched donors are unavailable or impractical. The findings could ultimately broaden the donor pool and improve access to potentially lifesaving stem cell transplants for patients with leukemia, lymphoma, myelodysplastic syndromes and other blood cancers.