Plasma biomarkers in graft-versus-host disease: a new era?

Abstract

Acute graft versus host disease (GVHD) remains a major complication of allogeneic hematopoietic cell transplantation (HCT). The diagnosis of acute GVHD is based on strictly clinical criteria and its severity also determined by these criteria. Currently, there is no validated diagnostic blood test for acute GVHD. This review will summarize proteomics approaches to identify biomarkers for GVHD in the plasma with diagnostic, prognostic and predictive value. If successful, these studies could establish a novel biomarker panel that will contribute important information including long term survival, and that may eventually facilitate therapeutic decisions for allogeneic HCT patients.

Fig 1. Antibody array heatmap of discovery set samples

This heatmap depicts relative protein values obtained from antibody microarrays after removal of batch effects due to three separate analyses. Samples from 21 GVHD–patients (left panel) and 21 GVHD+ patients (right panel) are represented. Only the antibodies giving the 35 smallest p-values for differences between GVHD+ and GVHD– patient plasma are shown. P-values compare GVHD+ and GVHD–samples. Reproduced with permission from reference .

Fig 2. Receiver Operating Characteristic (ROC) curves of four individual discriminator proteins and the composite panel in the training set

Individual ROC curves for IL-2Rα (- - - -), TNFR1 (——), HGF ( ) and IL-8 () and the composite panel (———). Reproduced with permission from reference .

Fig 3. Low and high risk groups correlate to GVHD grades

The blue boxes represent the low risk groups and the red boxes the high risk groups in the training (Panel A) and validation (Panel B) sets. The filled blue colors represent the GVHD grade 0 and the filled red colors the GVHD grade 1–4.

Fig 4. Non-relapse mortality (NRM) and overall survival (OS) stratified by the biomarker panel in the training set (Panel A) and validation set (Panel B)

In Panel A, the cumulative incidence of NRM and OS (determined by Kaplan Meier) are plotted according to the predicted probability of acute GVHD: low (—, n = 193) and high (- - -, n = 89). P = 0.001 and 0.006 (adjusted for age, donor type, HLA-match and intensity of conditioning) for differences in NRM and OS, respectively. The NRM at 3.5 years is 15% [95% CI, 9%–21%] for the low risk group and 36% [95% CI, 24%–48%] for the high risk group. OS at 3.5 years is 53% [95% CI, 45%–63%] for the low risk group and 33% [95% CI, 22%–48%] in the high risk group. In Panel B, the cumulative incidence of NRM and OS of the two groups are plotted for the validation set: low (—, n = 93) and high (- - -, n = 49). P < 0.001 and 0.02 (adjusted as before) for differences in NRM and OS, respectively. The NRM at 3.5 years is 11% [95% CI, 4%–19%] for the low risk group and 38% [95% CI, 23%–53%] for the high risk group. OS at 3.5 years is 59% [95% CI, 49%–72%] for the low risk group and 44%, [95% CI, 31%–63%] for the high risk group. Reproduced with permission from reference .

Fig 5. Intact Protein Analysis System workflow and in-depth analysis of plasma proteins

Plasma pooled from ten patients with GVHD are labeled with the heavy isotope and compared to plasma pooled from ten patients with no GVHD labeled with the light isotope. The specimens are then subjected to extensive fractionation (by ion-exchange chromatography and reversed-phase chromatography) before analysis of individual fractions. The result is a reduced complexity of individual fractions subjected to analysis by liquid chromatography – tandem mass spectrometry (LC-MS/MS). Adapted from reference .