From the inside: GVHD and glucose metabolism

T-Cell Metabolism in Graft Versus Host Disease

Allogeneic-hematopoietic stem cell transplantation (allo-HSCT) represents the only curative treatment option for numerous hematological malignancies. Elimination of malignant cells depends on the T-cells' Graft-versus-Tumor (GvT) effect. However, Graft-versus-Host-Disease (GvHD), often co-occurring with GvT, remains an obstacle for therapeutic efficacy. Hence, approaches, which selectively alleviate GvHD without compromising GvT activity, are needed. As already explored for autoimmune and inflammatory disorders, immuno-metabolic interventions pose a promising option to address this unmet challenge. Being embedded in a complex regulatory framework, immunological and metabolic pathways are closely intertwined, which is demonstrated by metabolic reprograming of T-cells upon activation or differentiation. In this review, current knowledge on the immuno-metabolic signature of GvHD-driving T-cells is summarized and approaches to metabolically interfere are outlined. Furthermore, we address the metabolic impact of standard medications for GvHD treatment and prophylaxis, which, in conjunction with the immuno-metabolic profile of alloreactive T-cells, could allow more targeted interventions in the future.

18F-FDG-PET-MRI for the assessment of acute intestinal graft-versus-host-disease (GvHD)

Background

Graft versus host disease (GvHD) is a frequent complication of allogeneic stem cell transplantation (alloSCT), significantly increasing mortality. Previous imaging studies focused on the assessment of intestinal GvHD with contrast-enhanced MRI/CT or ¹⁸F-FDG-PET imaging alone. The objective of this retrospective study was to elucidate the diagnostic value of a combined ¹⁸F-FDG-PET-MRI protocol in patients with acute intestinal GvHD.

Methods

Between 2/2015 and 8/2019, 21 patients with acute intestinal GvHD underwent ¹⁸F-FDG-PET-MRI. PET, MRI and PET-MRI datasets were independently reviewed. Readers assessed the number of affected segments of the lower gastrointestinal tract and the reliability of the diagnosis on a 5-point Likert scale and quantitative PET (SUVmax, SUVpeak, metabolic volume (MV)) and MRI parameter (wall thickness), were correlated to clinical staging of acute intestinal GvHD.

Results

The detection rate for acute intestinal GvHD was 56.8% for PET, 61.4% for MRI and 100% for PET-MRI. PET-MRI (median Likert-scale value: 5; range: 4–5) offers a significantly higher reliability of the diagnosis compared to PET (median: 4; range: 2–5; p = 0.01) and MRI alone (median: 4; range: 3–5; p = 0.03). The number of affected segments in PET-MRI (r_s = 0.677; p <  0.001) and the MV (r_s = 0.703; p <  0.001) correlated significantly with the clinical stage. SUVmax (r_s = 0.345; p = 0.14), SUVpeak (r_s = 0.276; p = 0.24) and wall thickening (r_s = 0.174; p = 0.17) did not show a significant correlation to clinical stage.

Conclusion

¹⁸F-FDG-PET-MRI allows for highly reliable assessment of acute intestinal GvHD and adds information indicating clinical severity.

Fluorodeoxyglucose F 18 for the Assessment of Acute Intestinal Graft-versus-Host Disease and Prediction of Response to Immunosuppressive Therapy

Graft-versus-host disease (GVHD) is a common complication that increases morbidity and mortality after allogeneic stem cell transplantation (allo-SCT). Fluorodeoxyglucose F 18 (¹⁸F-FDG)-positron emission tomography (PET) imaging has been demonstrated to be highly informative for evaluating and mapping of intestinal GVHD. To corroborate and extend existing findings and to investigate whether glucose metabolism assessed by ¹⁸F-FDG-PET might be an effective diagnostic tool to predict corticosteroid-refractory acute GVHD and overall survival. In this retrospective analysis, 101 patients with clinically suspected acute intestinal GVHD underwent ¹⁸F-FDG-PET between June 2011 and February 2019. Seventy-four of these patients with clinically and/or histologically proven acute intestinal GVHD as well as positive ¹⁸F-FDG-PET findings were analyzed in detail to assess the predictive value of ¹⁸F-FDG-PET regarding the response to immunosuppressive therapy and survival. Quantitative PET parameters, particularly the maximum standard uptake value (SUVmax), of patients with a fast response (ie, clinical improvement and decreased GVHD activity by at least 1 stage after 1 week of GVHD treatment) or slow/no response (ie, persistent disease activity for more than 1 week or increasing GVHD activity following first-line immunosuppressive therapy) were evaluated. ¹⁸F-FDG-PET detected intestinal GVHD with a sensitivity of 93% (95% confidence interval [CI], 85% to 97%) and specificity of 73% (95% CI, 45% to 91%). Patients with a fast response to immunosuppressive therapy had a mean SUVmax of 13.7 (95% CI, 11.0 to 16.5) compared with 7.6 (95% CI, 7.0 to 8.3; P = .005) observed in patients with prolonged or no response. The median overall survival (OS) was 573.0 days (95% CI, 539.5 to 606.5 days) for patients with fast response versus 255 days (95% CI, 161.0 to 349.0 days; P = .009) for patients with slow or no responses. A SUVmax threshold >8.95 applied to ¹⁸F-FDG-PET performed within 100 days after transplantation identified patients with a median OS of 390 versus 117 days for patients with SUVmax ≤8.95 (P = .036). SUVmax threshold and donor type were independent factors for OS. Our results indicate that ¹⁸F-FDG-PET is highly accurate in identifying patients with acute intestinal GVHD and may predict responses to immunosuppressive therapy as well as survival, particularly when applied within the first 100 days after transplantation. These results provide a strong rationale to integrate PET imaging in future prospective trials evaluating new therapies for acute GVHD.