Groundbreaking research suggests that faecal microbiota transplantation (FMT) can significantly improve outcomes for cancer patients who don’t respond to standard immunotherapy treatments. A small clinical trial focused on kidney cancer patients revealed that those receiving stool transplants from individuals who had successfully responded to checkpoint inhibitors experienced longer tumour stabilisation and higher rates of tumour shrinkage compared to a placebo group.
The Gut-Cancer Connection
The gut microbiome – the community of bacteria living in the digestive system – has emerged as a critical factor in cancer treatment success. Immunotherapy drugs, called checkpoint inhibitors, rely on the immune system to destroy cancer cells, but these drugs aren’t universally effective. Studies suggest that the composition of gut bacteria directly influences immune function, potentially explaining why some patients respond while others do not. The hypothesis is simple: altering the microbiome can boost immunity and enhance the body’s ability to fight cancer.
Trial Details and Results
Researchers at the Catholic University of the Sacred Heart in Rome, Italy, enrolled 45 adults with kidney cancer already undergoing treatment with pembrolizumab and axitinib. Participants were randomly assigned to receive either a stool transplant from a cancer remission patient or a saline solution (placebo) administered via a small tube into the large intestine. Subsequent doses were delivered orally in pill form.
The results were striking: The FMT group experienced an average of two years of tumour stabilisation, versus just nine months in the placebo group. Over half of the FMT recipients saw their tumours shrink, compared to about a third in the placebo cohort. This suggests that FMT can meaningfully improve immunotherapy effectiveness.
How Does it Work? The Role of Gut Bacteria
Analysis of stool samples reveals that FMT appears to introduce key bacterial species, notably Blautia wexlerae, which produces short-chain fatty acids known to stimulate anti-cancer immune cells. The transplants also reshaped existing gut flora, reducing harmful inflammatory strains of Escherichia coli while increasing levels of Ruminococcus bromii, another bacteria promoting beneficial short-chain fatty acid production.
These findings align with other recent trials, including one showing similar FMT-driven improvements in patients with non-small cell lung cancer. This growing body of evidence suggests that FMT could be effective against a range of cancers responsive to checkpoint inhibitors, including bladder and head and neck cancers.
Future Implications
While promising, these studies are small and require confirmation through larger, randomised controlled trials. Researchers are also focused on identifying the specific bacterial strains responsible for the therapeutic effects, with the ultimate goal of creating artificial microbial samples for scalable cancer treatment.
FMT represents a paradigm shift in how we approach cancer therapy. By manipulating the gut microbiome, doctors may soon be able to unlock the full potential of immunotherapy for a broader range of patients.
