Gut Bacteria May Boost Immunotherapy Responses in Some Rare Cancers

Certain strains of gut bacteria may boost immunotherapy response in some patients with rare cancers, according to a recent study published in the journal Nature Medicine.

Researchers from a phase 2 trial found that specific bacteria in the gut microbiome could help determine whether patients would derive the best benefit from immunotherapy combinations. This is important because it may help with the development of next-generation probiotics and individualized treatments, according to a press release.

“Our study shows that understanding the microbiome at strain-level, not just species-level, can open up a new level of personalized medicine. Having that extra resolution is crucial if we are to understand what is happening in the human body and the interplay between cancer treatment and the microbiome,” first study author Ashray Gunjur, from the Wellcome Sanger Institute and the Olivia Newton-John Cancer Research Institute, Australia, said in the press release. “Being able to test the specific mechanisms of this relationship between specific strains and response is the next horizon in this research, and one that could benefit human health in a multitude of ways.”

The trial included 120 patients, all of whom had advanced rare solid-organ cancers, the study noted. Patients were placed into cohorts depending on their cancer types, which included upper gastrointestinal and biliary cancers, neuroendocrine neoplasms and rare gynecological tumors.

The majority of patients (108 of 120 patients) had previously received at least one line of treatment for their cancers, the study established. Within the study, all patients received a treatment combination of Yervoy (ipilimumab) and Opdivo (nivolumab), followed by Opdivo as maintenance for up to two years or until patients experienced disease worsening or spreading, or unacceptable toxicities.

READ MORE: Gut Microbiota Differs in Patients With MPNs

To evaluate the gut microbiome of each patient, researchers collected fecal samples. They found that the most “beneficial” strains of bacteria — ones that led to better responses on immunotherapy — were from the ruminococcaceae family, an important type of bacteria that is commonly found in the gut microbiota, according to a study published in the journal Microbial Genomics.

“Rare cancers can be hard to study and treat and while immunotherapy treatment can be incredibly effective in some of these cases, it can also be unpredictable. Our research shows that the microbiome impacts how well someone responds to combination immunotherapy, but that monotherapy gives a different result. This suggests that the microbiome should be taken into account when developing therapeutics going forward,” said senior co-author David Adams, Wellcome Sanger Institute. “In addition to this, there is a possibility of developing live biotherapeutic products that could provide the bacteria shown to support immunotherapy, helping the microbiome work with the patient to give them the best odds of response possible.”

The researchers also analyzed previous studies and established that microbiome signatures could be applied to different cancers that were not evaluated in the trial, such as melanoma, which may help predict whose cancers will most likely respond to immunotherapy treatment combinations.

“Our microbiomes vary from person to person, all of us containing a different ecosystem of bacteria and other organisms that shape our responses to the world around us,” explained co-author Trevor Lawley, Wellcome Sanger Institute. “Our research highlights how an individual’s microbiome can predict how they will respond to cancer treatment, which can have a direct clinical impact by identifying those that would benefit the most, and aid in the design of future clinical trials.”

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