Single-Nucleotide Polymorphisms Within the Thrombomodulin Gene (THBD) Predict Mortality in Patients With Graft-Versus-Host Disease.

PURPOSE: Steroid-refractory graft-versus-host disease (GVHD) is a major and often fatal complication after allogeneic stem-cell transplantation (alloSCT). Although the pathophysiology of steroid refractoriness is not fully understood, evidence is accumulating that endothelial cell stress is involved, and endothelial thrombomodulin (THBD) plays a role in this process. Here we assess whether single-nucleotide polymorphisms (SNPs) within the THBD gene predict outcome after alloSCT. PATIENTS AND METHODS: Seven SNPs within the THBD gene were studied (rs1962, rs1042579, rs1042580, rs3176123, rs3176124, rs3176126, and rs3176134) in a training cohort of 306 patients. The relevant genotypes were then validated in an independent cohort (n = 321).
RESULTS: In the training cohort, an increased risk of nonrelapse mortality (NRM) was associated with three of seven SNPs tested: rs1962, rs1042579 (in linkage disequilibrium with rs3176123), and rs1042580. When patients were divided into risk groups (one v no high-risk SNP), a strong correlation with NRM was observed (hazard ratio [HR], 2.31; 95% CI, 1.36 to 3.95; P = .002). More specifically, NRM was predicted by THBD SNPs in patients who later developed GVHD (HR, 3.03; 95% CI, 1.61 to 5.68; P < .001) but not in patients without GVHD. In contrast, THBD SNPs did not predict incidence of acute GVHD. Multivariable analyses adjusting for clinical variables confirmed the independent effect of THBD SNPs on NRM. All findings could be reproduced in the validation cohort.
CONCLUSION: THBD SNPs predict mortality of manifest GVHD but not the risk of acquiring GVHD, supporting the hypothesis that endothelial vulnerability contributes to GVHD refractoriness.