High Graft CD8 Cell Dose Predicts Improved Survival in Allogeneic Stem Cell Transplantation With Reduced-Intensity Conditioning
In a single-institution study reported in the Journal of Clinical Oncology, Reshef et al found that high graft CD8 cell dose was associated with improved overall survival among patients with hematologic malignancy receiving allogeneic stem cell transplantation with reduced-intensity conditioning. High graft CD8 cell content was associated with younger donor age.
High CD8 Cell Dose
The study involved 200 adults undergoing allogeneic stem cell transplantation at the University of Pennsylvania. In multivariate analysis, higher CD8 cell dose was an independent predictor of reduced risk of relapse (adjusted hazard ratio [HR] = 0.43, P = .009), relapse-free survival (HR = 0.50, P = .006), and overall survival (HR = 0.57, P = .04), with no significant association seen between higher CD8 cell dose and increased risk of graft-vs-host disease or nonrelapse mortality. A cutoff level of 0.72×108 CD8 cells/kg provided optimal segregation of patients receiving CD8-high and CD8-low grafts for relapse-free survival (P = .005) and overall survival (P = .007). Crude 1-year overall survival rates were 77% for those receiving CD8-high grafts and 50% for those receiving CD8-low (P < .001), with survival rates remaining significantly different 4 years after transplantation.
Association With Donor Age
Donor age was inversely correlated with graft CD8 dose: CD8-high grafts were provided by 0% of donors aged > 60 years, 13% of those aged > 50 years, 40% of those aged < 50 years, and 53% of those aged < 30 years. Compared with recipients of older sibling donor grafts (consistently containing CD8-low doses), survival was significantly better among recipients of younger unrelated donor grafts with CD8-high doses (P = .03) but not among recipients of younger unrelated donor CD8-low grafts (P = .28).
Assessment of 21 allogeneic stem cell transplantation donors showed that graft CD8 content could be predicted from the proportion of CD8 cells in screening blood samples.
The investigators concluded: “Higher graft CD8 dose, which was restricted to young donors, predicted better survival in patients undergoing [reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation].”
Ran Reshef, MD, of University of Pennsylvania, is the corresponding author of the Journal of Clinical Oncology article.
The study was supported by the National Institutes of Health, Conquer Cancer Foundation, National Marrow Donor Program, and Commonwealth Universal Research Enhancement Program from the Commonwealth of Pennsylvania. For full disclosures of the study authors, visit jco.ascopubs.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
