A new study from Italy has shown that gut microbiota transplants—also known as fecal microbiota transplantation (FMT)—may improve the success of immunotherapy in people with advanced kidney cancer.
This breakthrough could lead to better outcomes for patients who have limited treatment options.
The study, published in the journal Nature Medicine, was led by researchers from Università Cattolica del Sacro Cuore and Fondazione Policlinico Gemelli IRCCS.
It focused on people with metastatic renal cell carcinoma (mRCC), a serious type of kidney cancer that has spread to other parts of the body.
In recent years, immunotherapy has transformed cancer treatment. These drugs work by waking up the immune system to fight cancer. But many patients either don’t respond or see limited benefits.
Scientists have been looking for ways to improve these results. One key area of interest is the gut microbiota—the collection of bacteria and microbes in the digestive system.
The gut microbiota has a strong influence on the immune system. In kidney cancer, inflammation and other factors in the body can weaken the effects of immunotherapy. The research team believed that changing the gut microbiota might help patients respond better to treatment.
They designed a clinical trial called TACITO. It was a randomized, double-blind, placebo-controlled study, meaning neither doctors nor patients knew who was getting the real treatment or a fake one.
The study tested whether a stool transplant from healthy donors who had fully responded to immunotherapy could improve the effectiveness of the standard treatment for kidney cancer.
All 45 patients in the study received two common treatments: pembrolizumab (a type of immunotherapy) and axitinib (a targeted therapy that blocks blood flow to tumors). Some patients also received a fecal microbiota transplant from a successful donor, while others received a placebo.
After one year, 70% of the patients who got the transplant had no disease progression, compared to 41% of those who got the placebo. While this difference wasn’t statistically significant for the main goal of the study, other results were more striking.
The average time before the cancer got worse was much longer—24 months for the transplant group versus just nine months for the placebo group. This showed a 50% lower risk of disease progression.
The response rate—meaning the percentage of people whose cancer shrank or disappeared—was also higher: 52% in the transplant group versus 32% in the placebo group. The benefits were even greater for patients who had a worse outlook at the start.
The researchers confirmed that the new bacteria from the donor stool successfully took hold in the patient’s gut, increasing microbial diversity—a good sign of gut health. But they also found that success was linked more closely to changes in specific “bad” bacteria than overall diversity.
Safety was a top priority. Donor stool was carefully tested for bacteria, viruses, and parasites, and all procedures were done under strict safety standards.
“These results suggest that changing the gut microbiota could give the immune system a better chance to fight cancer,” said Dr. Gianluca Ianiro, one of the lead researchers.
The team hopes to confirm their findings in larger studies. They also plan to explore new ways to adjust the gut microbiota, such as using capsules or specific mixtures of healthy bacteria. In the future, doctors might even use gut bacteria as a sign to predict who will benefit most from immunotherapy.
If confirmed, this could be a big step toward making cancer treatment more effective, personalized, and safer for people with advanced kidney cancer.
If you care about cancer, please read studies that artificial sweeteners are linked to higher cancer risk, and how drinking milk affects risks of heart disease and cancer.
For more health information, please see recent studies about the best time to take vitamins to prevent heart disease, and results showing vitamin D supplements strongly reduces cancer death.
Copyright © 2025 Knowridge Science Report. All rights reserved.
