# Take faecal transplant plus immunotherapy to a definitive trial

Source: https://onco.cc/ideas/idea-bio2-fmt-plus-checkpoint-phase3/  
OnCo record `idea-bio2-fmt-plus-checkpoint-phase3` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Transferring gut bacteria from patients who responded to immunotherapy has helped some patients who had stopped responding. It is time for a proper large trial.

## Summary

Two independent phase 1 studies reported that faecal microbiota transplant from checkpoint responders re-sensitised some anti-PD-1-refractory melanoma patients, and a first-line study of donor transplant with checkpoint blockade showed feasibility and encouraging response. The field has stayed in small single-arm studies for years. A randomised trial with a defined donor consortium, standardised product and pre-specified microbiome endpoints would settle whether the effect is real.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Faecal microbiota transplant from selected responder donors plus anti-PD-1 improves response rate compared with anti-PD-1 alone in checkpoint-refractory melanoma, with engraftment of donor taxa as a mechanistic mediator.
- Rationale: The mouse causal data are strong, human phase 1 signals are reproducible across two centres, and the intervention is inexpensive. The main risks are donor variability and product standardisation, both addressable through consortium banking.
- Proposed test: A randomised phase 2 with pooled standardised donor product, primary endpoint objective response, and mandatory metagenomic sequencing to link engraftment with response.
- Maturity: early-clinical
- Actor: research

## Sources

- Bottleneck evidence (No one can predict who responds to immunotherapy): Haslam & Prasad (JAMA Network Open 2019): https://doi.org/10.1001/jamanetworkopen.2019.2535

## Connected records

- cancers: [Melanoma](https://onco.cc/cancers/melanoma/), [Renal cell carcinoma](https://onco.cc/cancers/rcc/)
- technologies: [Faecal microbiota transplantation for PD-1 non-responders](https://onco.cc/technologies/fmt-checkpoint-nonresponders/), [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- drugs: [Nivolumab](https://onco.cc/drugs/nivolumab/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- institutions: [Gustave Roussy](https://onco.cc/institutions/gustave-roussy/), [Princess Margaret Cancer Centre](https://onco.cc/institutions/princess-margaret/)
- people: [Laurence Zitvogel](https://onco.cc/people/laurence-zitvogel/)
- bottlenecks: [Cold tumours and the immunosuppressive microenvironment](https://onco.cc/bottlenecks/b-tme-immunosuppression/), [No one can predict who responds to immunotherapy](https://onco.cc/bottlenecks/b-immunotherapy-response/)
- key papers: [Estimation of the Percentage of US Patients With Cancer Who Are Eligible for and Respond to Checkpoint Inhibitor Immunotherapy Drugs](https://onco.cc/key-papers/paper-haslam-jama-netw-open/)
- trials: [FMT plus pembrolizumab in anti-PD-1-refractory melanoma (Pittsburgh)](https://onco.cc/trials/fmt-pd1-refractory-melanoma-pitt/), [MIMic-01: healthy-donor FMT plus anti-PD-1, first-line melanoma](https://onco.cc/trials/mimic-01/)

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