PhD Scientific Days 2026

Theoretical and Translational Medicine 4.

Fecal microbiota transplantation as a therapeutic option in adult patients with acute steroid-refractory intestinal graft-versus-host disease

Name of the presenter

Szabó, Bálint Gergely

Institute/workplace of the presenter

Semmelweis University, Department of Internal Medicine and Haematology, Departmental Group of Infectious Disease

Authors

Bálint Gergely Szabó¹
1: Semmelweis University, Department of Internal Medicine and Haematology, Departmental Group of Infectious Disease

Text of the abstract

Introduction: Intestinal acute graft-versus-host disease (aGVHD) is a severe complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). In steroid-refractory (SR) disease, the introduction of alternative therapeutic strategies is required.

Aims: Our aim was to investigate safety and efficacy of fecal microbiota transplantation (FMT) in adult patients who developed intestinal SR-aGVHD after allo-HSCT.

Methods: Our study included consecutive patients treated at our center between 2023-2024, who were followed per protocol until day +180 post-FMT. The primary clinical and microbiological endpoints were GVHD activity, overall survival, and intestinal microbiome regeneration. Data were evaluated with reference to both the patients’ baseline microbiome and that of the donor stool composition. High-resolution stool microbiome analysis was performed using 16S metagenome-sequencing.

Results: A total of 16 patients were included in the study. The indication for allo-HSCT was acute leukemia in 12 cases. GVHD developed a median of 40 days after HSCT. Despite first-line steroid therapy, disease severity remained unchanged in 7, and progressed in 4. By day +180 after FMT, complete GVHD remission was achieved in 10/16 (62.5%), GVHD progression was observed in 2/16 (12.5%), and no change occurred in 1/16 patients (6.3%). Three patients died by day +30, despite initial GVHD remission. Among patients who achieved complete remission, genus-level microbiome composition was already similar to the donor’s at baseline in 1 patient. In another, similarity developed by day +7 post-FMT, following initial Proteobacteria dominance, while in a third patient, similarity emerged by day +180 post-FMT. In patients who did not achieve complete remission, relative abundances of Enterococcus and Enterobacter species decreased, while the microbiome composition moved closer to that of the donors. Among patients who died before day +180 and in the two patients with the most severe disease, low alpha-diversity was observed.

Conclusion: Based on our findings, we hypothesize that FMT may be an effective and safe therapeutic option for hematologic patients from intestinal SR-aGVHD.

Funding: EKÖP-2025-422, OTKA PD_23 147276

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This abstract is submitted to fulfill the mandatory reporting obligation for EKÖP-2025 scholarship.