A crucial part of our defense against disease, namely the composition and diversity of the gut microbiome, can even affect how cancer immunotherapy works. Nevertheless, little research is focused on the tumor microbiota, and how it affects prognosis and survival.
Microbes treat pancreatic cancer
Now, a study from researchers at MD Anderson Cancer Center shows the tumor microbiome influences the patient’s immune response and survival rate in pancreatic cancer. Furthermore, the results were gained using a fecal microbiota transplant, which could also act as a possible treatment. The team states their study demonstrates how pancreatic tumor microbiome cross-talks with the gut microbiome. It is in this way it influences the host immune response and survival rates. The study is published in the journal Cell.
Previous studies show the majority of patients with pancreatic ductal adenocarcinoma, the most common form of pancreatic cancer, have late-stage disease when diagnosed. Consequently, just 9 percent of these patients survive to five years. Still, patients with earlier stage cancer which can be surgically removed have a median survival of only 24-30 months.
To date, no genomic biomarkers have been identified to shed light on the reasons for long-term survival rates in patients. The current study investigates whether specific microbiota has a role in pancreatic cancer survival rates.
The current study analyzes the microbiome in pancreatic tumors of twenty-two long-term survivors, with a median survival of 10 years. In addition, these long-term survivors were matched to 21 short-term survivors, who have been given a median survival of 1.6 years.
Using cancer to fight cancer
Results show the long-term survivors’ tumors had a much greater diversity of bacterial species than the short-term survivors. Moreover, this diversity is independent of previous therapies, body mass index or antibiotics use. Subsequently making the tumor microbiome a predictor of survival for surgical patients.
Data findings show long-term survival patients had an intra-tumoural microbiome signature containing Pseudoxanthomonas-Streptomyces-Saccharopolyspora-Bacillus clausii bacteria specifically. Moreover, the gut microbiome represented roughly 25 percent of the tumor microbiome.
Furthermore, the lab observed a strong correlation between immune infiltration, activation of T cells, and the three enriched bacterial types identified on long-term survivors’ tumors.
Fecal transplants and cancer
To test the link between the tumor microbiome, the gut microbiome, and immune response, the group transplanted fecal microbiota from patients with advanced cancer into mice. Indeed, it was shown that seventy percent of the overall tumor microbiome had been altered by the transplant. Similarly, the fecal microbiota transplant was also able to affect tumor growth and tumor immune infiltration. Thus, fecal transplants were able to alter the tumor microbiome to treat pancreatic cancer in mice.
The team surmises their data shows the specific tumor microbiome is tied to long-term survival. Additionally pointing to fecal transplant as a treatment. For the future, the researchers state their data suggests fecal microbiota transplants represent a significant therapeutic opportunity to improve pancreatic cancer treatment by altering the tumor immune microenvironment.
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