Predictors of recovery following allogeneic CD34+-selected cell infusion without conditioning to correct poor graft function

Poor graft function is a serious complication following allogeneic hematopoietic stem cell transplantation. Infusion of CD34+-selected stem cells without pre-conditioning has been used to correct poor graft function, but predictors of recovery are unclear. We report the outcome of 62 consecutive patients who had primary or secondary poor graft function who underwent a CD34+-selected stem cell infusion from the same donor without further conditioning. Forty-seven of 62 patients showed hematologic improvement and became permanently transfusion- and growth factorindependent. In multivariate analysis, parameters significantly associated with recovery were shared cytomegalovisur seronegative status of both the recipient and donor, the absence of active infection and matched recipientdonor sex. Recovery was similar in patients with mixed and full donor chimerism. Five-year overall survival rates were 74.4% (95% confidence interval [95% CI: 59-89]) in patients demonstrating complete recovery, 16.7% (95% CI: 3-46) in patients with partial recovery and 22.2% (CI 95% 5-47) in those who had no response. In patients with blood count recovery, those with poor graft function in one or two lineages had a better 5-year overall survival (93.8%, 95% CI: 82-99) than those with trilineage failure (53%, 95% CI: 34-88). New strategies including cytokine or agonist support, or a second transplant need to be investigated in patients whose blood counts do not recover.