Researchers developed a predictive score for the risk of graft failure in patients with acute leukemia who underwent allogeneic hematopoietic stem cell transplantation (aHSCT) with ex vivo T-cell depletion. T-cell depletion is performed in an effort to prevent subsequent graft-versus-host disease (GVHD) after transplant.
The risk score was based on patient age and the T-lymphocyte population pre-aHSCT with 1 point of risk possible in each category. Patients with 1 point had a graft failure risk of 5% and 13% if they had 2 points, according to the results of the study presented at the virtual meeting of the European Society for Blood and Marrow Transplantation.
Graft failure is a potentially severe complication in patients treated with aHSCT, but there are few studies analyzing risk factors when ex vivo T-cell depletion is used, Ivan López Torija of the Hospital Infantil Universitario Niño Jesús, Madrid, and colleagues noted in their presentation, which won the Best Young Poster Abstract Award at the meeting.
The researchers assessed 148 pediatric patients (64% boys) with acute leukemia who underwent allogeneic HSCT from haploidentical donors using ex vivo T-cell depletion between 2005 and 2020. About 53% of the patients were diagnosed with acute lymphoblastic leukemia, the rest with acute myeloid leukemia. The donor mean age was 40 years, and all transplant patients received toxicity reduction conditioning based on fludarabine busulfan and thiotepa.
Multivariate analysis showed that T-cell count (CD3+/CD8+ ≥ 350/mL: hazard ratio, 2,6; P = .01) and patient age (less than 9 years: HR; 5.0; P = .04) were associated with graft failure. A risk score was established using these results and based on patient age and T lymphocyte pre-aHSCT with 1 point each for each increased risk category. Patients with 1 point had a graft failure risk of 5% and a risk of 13% if they had 2 points.
However, in this particular population, with a mean follow up of 4 years, the overall survival rate was 60%, with no significant differences seen between patients that presented graft failure and those without graft failure.
“Patient age and pretransplant number of CD3+/CD8+ are associated with [graft failure] in pediatric patients with acute leukemia undergoing ex vivo T-cell–depleted haploidentical transplantation. These findings highlight the importance of preexisting cellular immunity in the transplant recipient and support T-cell population analysis as part of a pretransplant working program,” the researchers concluded.
The authors reported that they had no disclosures.