2018 BMT Tandem Meetings
SALT LAKE CITY—Researchers say they have identified prognostic biomarkers for chronic graft-vs-host disease (cGVHD) in children.
The group found that recent thymic emigrants (RTEs) and regulatory T cells expressing CD31 and CD45RA (Treg RTEs) were significantly lower at day 100 after transplant in patients who developed cGVHD.
Because prior research indicated that RTEs are higher in adults with cGVHD, the researchers concluded that thymic function may play a bigger role in cGVHD development for children than for adults.
Geoff D.E. Cuvelier, MD, of CancerCare Manitoba in Winnipeg, Canada, presented these findings at the 2018 BMT Tandem Meetings (abstract 104).
“Our group became interested in these populations of recent thymic emigrants when 2 adult studies1,2 . . . showed that higher proportions of recent thymic emigrants at day 100 were prognostic for the development of chronic graft-vs-host disease,” Dr Cuvelier said.
This led his group to evaluate whether RTEs (CD4+CD45RA+CD31+ T cells), as well as Treg RTEs—Tregs (CD4+CD25+CD127Low) that co-express naïve and recently emigrated markers (CD45RA+CD31+)—are prognostic for pediatric cGVHD at day 100 after allogeneic hematopoietic stem cell transplant (allo-HSCT).
The researchers’ study enrolled patients younger than 18 years of age who underwent allo-HSCT to treat malignant and non-malignant diseases. There were 144 patients who had 1 year of follow-up after allo-HSCT.
Thirty-seven of the patients (25.7%) had cGVHD, and 34 (23.6%) had late acute GVHD (post-day 100). The remaining 73 patients (50.7%) had neither cGVHD nor late acute GVHD, so they served as controls.
Twenty cases of cGVHD were severe, 12 were moderate, and 5 were mild. cGVHD was initially diagnosed at a mean of 192 days post-transplant. The median number of organ systems involved was 3 (range, 1-6). Seventeen patients (46%) had overlap syndrome.
The researchers found that RTEs as a percentage of CD4 T cells were significantly lower at day 100 in patients with cGVHD than in controls—7.8% and 13.5%, respectively (P=0.007). The difference between controls and patients with late acute GVHD was not significant—13.5% and 9.4%, respectively (P=0.08).
Treg RTEs as a percentage of all Tregs were also significantly lower at day 100 in patients with cGVHD than in controls—6.4% and 13.2%, respectively (P=0.002). Again, the difference between controls and patients with late acute GVHD was not significant—13.2% and 9.1%, respectively (P=0.06).
However, further analysis revealed that percentages of RTEs and Treg RTEs were significantly lower at day 100 in patients who developed any type of GVHD after day 100.
The percentage of RTEs was 13.5% in controls and 8.5% in patients with any GVHD after day 100 (P=0.009). The percentage of Treg RTEs was 13.2% and 7.6%, respectively (P=0.004).
“Both recent thymic emigrants and Treg RTEs at day 100 are prognostic biomarkers for chronic graft-vs-host disease in children in this large, multi-institutional, prospective trial,” Dr Cuvelier said in closing.
“Unlike adults, in children, RTEs are proportionally lower, not higher, in patients that later develop chronic GVHD compared to no chronic GVHD. This may suggest that thymic dysfunction and thymic output may play a greater role in chronic GVHD development in children compared to adults.”
To expand upon this research, Dr Cuvelier and his colleagues are planning to begin model building using prognostic cellular and plasma biomarkers at day 100 to determine high-risk profiles for cGVHD.
1. Greinix HT et al; CD19+CD21low B Cells and CD4+CD45RA+CD31+ T Cells Correlate with First Diagnosis of Chronic Graft-versus-Host Disease. BBMT 2015; 21(2):250-258.
2. Li AM et al. An Early Naïve T Cell Population Lacking PD1 Expression at Day 100 As A Prognostic Biomarker of Chronic GVHD. TSS 2017; 210.6.