Impact of High Donor-Derived CD4+ CCR7+ T Cell Count on Incidence of Grade II-IV Acute Graft-Versus-Host Disease Following Haploidentical Hematopoietic Cell Transplantation
Abstract Introduction Historically the administration of post-transplant high-dose Cyclophosphamide (PTCy) has led to haplo-HCT re-innovation. Although PTCy has a positive impact towards reducing severe acute graft-versus-host disease (aGVHD), this drug has serious adverse side effects and makes haploidentical-HCT more difficult in some patients-particularly in older patients and/or those presenting other comorbidities. Considering our previous published experience in the effect of graft lymphocyte composition, this work aims to explore the impact of infused T cell subsets on Overall Survival (OS), Event Free Survival (EFS) and acute GVHD in a retrospective cohort receiving allogeneic haplo-HCT. Methods This study retrospectively analyzed 29 adult patients who underwent first allogeneic haplo-HCT for hematologic malignancies at Lille University Hospital (CHRU Lille, France). Graft samples were analyzed by flow cytometry, and CD4 and CD8 T cell subsets were defined as follows: TN=naïve T cells; , TCM=central memory T cells; TEM=effector memory T cells; TTD =terminally differentiated T cells. Results The median follow-up of patients was 11 months (0.4-44.3). The cohort median recipient age was 59 years old. Cumulative incidences of grade 2 to 4 aGVHD were 31%. The rate of grade 3 to 4 severe GVHD was 17%. Eleven patients died with 14% of deaths due to non-relapse mortality. We found a correlation between high percentage of donor-derived CD4+ CCR7+ T cells (>69.2% for CD4+ T cells-the median value in our study) and aGVHD (p=0.028) without any impact on OS and EFS (Table 1). In multivariate analysis, only high proportions of donor CD4+ CCR7+ T cells correlated significantly with aGVHD (HR=0.203, 95% CI [0,042-0,980], p=0,047) without any impact on OS and EFS (Figure 1). Conclusion Naïve and central memory T cells expressing CCR7 exhibit higher alloreactivity potential than CCR7- T cells. In this study, even with PTCy administration, we observed that a high percentage of donor-derived CD4+ CCR7+ T cells can be considered as a predictive indicator of grade II-IV aGVHD post Haplo-HCT. Thus, selective depletion of CD4+ CCR7+ T cells might be enough to prevent aGVHD in haplo-HCT, enabling the use of low doses of PTCy in order to reduce post haplo-HCT complications. Disclosures No relevant conflicts of interest to declare.