▲ Professor Sook Ryun Park is consulting a patient with metastatic esophageal cancer.

Recent research has highlighted the significant role that gut microbiome plays in the treatment of various diseases, including metabolic disorders, cardiovascular diseases, autoimmune diseases, cranial nerve disorders, and cancer. This has led to growing global interest in the therapeutic potential of gut microbiome and fecal microbiota transplantation (FMT). In a study conducted by a team led by Professor Sook Ryun Park of the Division of Oncology at Asan Medical Center, it was demonstrated that fecal transplants could restore the effectiveness of immunotherapy in patients with advanced metastatic solid tumors who had developed resistance to treatment.

The research involved 13 patients with stage IV solid cancers of the liver, stomach, esophagus, and more who had developed resistance to immunotherapy. The feces from patients who had experienced complete or partial remission for at least 6 months following immunotherapy were transplanted into these patients, followed by re-administration of immunotherapy. Prior to the fecal transplantation, the recipients were administered oral antibiotics to deplete their existing gut microbiome. The donor feces were processed into a suspension and transplanted via colonoscopy. The recipients underwent immunotherapy and were monitored every 6-8 weeks through computed tomography (CT) to check their cancer status.

The results showed that one liver cancer patient of the 13 patients experienced a 48% partial remission, with the liver cancer tumor marker (AFP) level decreasing from 1,000,000 ng/ml to 3,000 ng/ml. Five other patients with metastatic cancer had no further progression. Additionally, the research team identified a new beneficial bacterium that enhanced the therapeutic effectiveness of fecal transplantation in overcoming immunotherapy resistance and named it ‘Prevotella merdae immunoactis.’ The team also discovered that ‘Bacteroides plebeius’ and ‘Lactobacillus salivarius’ are harmful bacteria that inhibit the effectiveness of immunotherapy.

This pioneering study is the first in the world to demonstrate the clinical efficacy of fecal microbiota transplantation in enhancing immunotherapy for metastatic solid tumors. The findings were recently published in ‘Cell Host & Microbe, a sister journal of the international journal ‘Cell.’