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The following is a summary of “A study protocol for a double-blinded, randomised, placebo-controlled trial on the use of encapsulated FMT for reducing the side effects of HSCT: the HSCT-BIOME study,” published in the April 2025 issue of the BMC Cancer by Li et al.

The gut microbiota has emerged as a critical factor influencing outcomes in patients undergoing hematopoietic stem cell transplantation (HSCT), with disruptions in microbial composition linked to increased infection rates, delayed immune recovery, and disease relapse. Fecal microbiota transplantation (FMT), an intervention aimed at restoring microbial balance, has shown therapeutic promise in HSCT recipients, primarily in treating recurrent infections. However, its use in the peri-transplant period remains underexplored. This study investigates the feasibility, safety, and effectiveness of administering encapsulated FMT before and after autologous HSCT to stabilize the gastrointestinal microbiome and improve clinical outcomes.

This multicenter, double-blind, randomized, placebo-controlled trial—referred to as the HSCT-BIOME study—enrolls adult patients with hematologic malignancies scheduled for autologous HSCT. Participants receive two courses of orally administered encapsulated FMT: the first dose is administered immediately prior to the initiation of conditioning therapy, and the second is given post-transplant, once ANC exceeds 0.8 × 10⁹/L. Following an initial open-label safety phase involving five patients, the main trial randomizes 51 participants in a 2:1 ratio to either the FMT or placebo groups.

The primary efficacy endpoint is the proportion of patients who develop severe gastrointestinal toxicity, defined as three consecutive days of diarrhea rated at 6 or higher on the Bristol Stool Chart and occurring at a frequency of four or more bowel movements per day within three weeks post-transplant. Safety is assessed by monitoring treatment-emergent adverse events (TE-AEs), while tolerability is evaluated based on TE-AEs and patient adherence to the FMT regimen.

The HSCT-BIOME trial is designed to assess whether FMT administered during the peri-transplant period—both before and after HSCT—can enhance microbial resilience and reduce post-transplant gastrointestinal complications. Administering FMT prior to conditioning and again during neutropenia represents a novel approach aimed at preserving or restoring microbiota diversity during critical periods of immunosuppression. The study’s findings will provide important insights into the role of microbiota-targeted interventions in HSCT and may pave the way for broader integration of microbiome-supportive therapies into standard transplant care.

Source: bmccancer.biomedcentral.com/articles/10.1186/s12885-025-14057-4