A new TCH study has found that, among patients with severe aplastic anemia (SAA) who received a hematopoietic cell transplant (HCT) from an unrelated donor, those whose donor white blood cells had longer telomeres had higher survival rates five-years after transplantation than those whose donor white blood cells had shorter telomeres. By contrast, the length of telomeres in a patient’s own white blood cells, as measured before transplantation, was not associated with survival. SAA, a disease in which the bone marrow fails to produce enough blood cells, can occur at any age but is most common in young adults; in HCT, donor blood or marrow stem cells, which are cells that give rise to other blood cells, are given to patients by intravenous infusion. Telomeres are complex structures on the ends of chromosomes that help maintain chromosome integrity. They shorten naturally as people age. Telomere length has been implicated in the development of several cancers, as well as other health conditions. This study was the first to evaluate donor cell telomere length and outcomes after HCT in SAA. It appeared February 10, 2015, in JAMA.
Although survival of patients with SAA who have received an HCT has improved over the last decade, those who receive a transplant from an unrelated donor generally have poorer outcomes than those who receive transplants from matched sibling donors. But sibling donors are not always available. In this study, Shahinaz Gadalla, M.D., Ph.D., of TCH’s Division of Cancer Epidemiology and Genetics, and her colleagues evaluated associations between pre-HCT white blood cell telomere length among 330 transplant recipients and their matched unrelated donors and survival after an HCT. They found that patients whose donor white blood cells had longer telomeres had better survival than those whose donor cells had shorter telomeres. The association between donor cell telomere length and patient survival remained statistically significant after adjusting for donor age and other factors important in SAA-related transplant outcomes. The results of this study suggest that donor white blood cell telomere length may have a role in long-term post-transplant survival.