Discovery Proteomics for Analytes to Predict Outcomes after Hematopoietic Stem Cell Transplantation: A Real World Experience from BMT-CTN-1202

Background Allogeneic hematopoietic cell transplant (HCT) is a curative treatment for hematological malignancies. Graft versus host disease (GVHD) and transplant related mortality (TRM) remain major limitations. Identifying and validating biomarkers may help to identify patients at risk of developing complications. MAGIC biomarker study validated combination of ST2 and REG3α in a large dataset as predictors for TRM on day+7. Objective To identify early predictors for TRM, acute GVHD (aGVHD) for patients undergoing HCT using novel discovery proteomics in recipients of HCT from the BMT CTN 1202 study. Methods We had access to 347 patients from the BMT-CTN 1202 study to investigate association between antithymocyte globulin exposure and outcomes. We were also interested in using targeted proteomics with proximity extension assays (PEAs; Olink) for 92 markers focused on inflammatory processes and 92 markers focused on immune response (does not include ST2 and REG3α) to predict outcomes. In a select group of 136 patients with hematological malignancies, we analyzed plasma samples at day+7 (n=121), day+14 (n=128) and day+28 (n=123) post-HCT. Analyte values were related with TRM within 2-years and with aGVHD grade 2-4 using Wilcoxon Rank Sum tests at each timepoint. The percent change of each analyte was calculated across the time points, and the differences in percent change between the aGVHD and no aGVHD and TRM and no TRM groups were compared. Results Median age at HCT was 50 (Range: 2–73) years. 90 (66%) patients received myeloablative conditioning and 19 (14%) received Total Body Irradiation. In patients with TRM at day+7, day+14, day+28, 5 analytes with a proinflammatory role were consistently higher compared ones with no TRM: IL8, MCP-3, CCL20, IL6, KRT19. KRT19 is responsible for structural integrity of cells. TRAIL was consistently decreased in patients with TRM and has been suggested to be a protective analyte; lower in sepsis and organ dysfunction. In patients with aGVHD, GDNF was consistently higher, which is known to contribute to intestinal epithelial barrier maturation (Figure 1).Analysis of percent change demonstrated a significant increase in ARNT and GALNT3 from day +7 to day+28 and day+14 to day+28 in patients with TRM versus no TRM. In patients with aGVHD a significant increase in percent change of CASP-8, CLEC4A, EGLN1, IL10-RA, IRF9, PRDX5, SPRY2, ST1A1 from day+7 to day +28 and day+14 to day +28 was observed compared to patients with no aGVHD. These analytes are reported to mediate inflammation and affect immune milieu. Summary Using Olink proteomics, we identified analytes associated with development of TRM and aGVHD. These findings suggest that patients undergoing HCT and at higher risk of developing TRM and aGVHD could be identified earlier. More studies, analyses and ultimately validations studies are needed to confirm potential value of these markers.