Transplanted intestinal bacteria give cancer patients a second chance

(CONNECT) A team of gastroenterologists from the University of Zurich (UZH) has found a way to trigger an immune response in patients for whom cancer immunotherapy has so far been unsuccessful, according to a press release. The path was revealed as part of the Zurich Microbiome Project, which was funded by the Comprehensive Cancer Center Zurich with 1.65 million Swiss francs from 2022 to the end of 2025. An interdisciplinary team at University Hospital Zurich and UZH investigated whether the gut microbiome, i.e. the entirety of bacteria in the gut, plays a role in the immune response. In recent years, studies around the world have shown that intestinal bacteria have a far greater influence on the immune system than previously assumed.

The Zurich team also gave fecal microbiota transfer (FMT) to patients whose tumors had not responded under an ongoing immune checkpoint blockade. The microbiome of a person who had undergone successful immunotherapy was transferred to them via colonoscopy. The result: the cancer therapy suddenly showed an effect in every second person who had previously been resistant to treatment.

Initially, the researchers believed that the exact composition of the microbiome made the difference. Instead, according to the new data, the decisive factor is which immune system the transplant encounters. Cancer patients with a certain population of monocytes in the intestine and a high diversity of T-cell receptors benefited significantly more often.

"The transfer changed the immunological and metabolic conditions in such a way that the existing therapy could become effective," Michael Scharl is quoted as saying. He is UZH Professor of Translational Microbiome Research and a gastroenterologist at the University Hospital Zurich. An FMT therefore does not create new immunological capabilities - it mobilizes existing ones.

According to UZH, the next clinical trial has already been initiated in order to give previously treatment-resistant patients a second chance: Together with the Schlieren-based ZüriPharm AG, a member of the Bio-Technopark Schlieren-Zurich, the conditions are to be created to transfer FMT into clinical routine in the future. ce/mm