Cancer immunotherapy has transformed the treatment of many types of cancer. Yet, for reasons that remain poorly understood, not all patients get the same benefit from these powerful therapies.

One potent factor in treatment outcome appears to be an individual's gut microbiota—the trillions of microorganisms that live in the human intestine—according to new research led by investigators at Harvard Medical School and Dana-Farber Cancer Institute.

The research found that specific gut bacteria can affect the activity of two immune molecules—PD-L2 and RGMb—as well as the interplay between them. The study also identifies the molecule RGMb as a previously unknown accomplice in sabotaging the body's ability to spot and destroy tumors. RGMb, primarily known for its role in nervous system development, is also found on the surface of cancer-fighting T cells. Until now, however, no one knew it played a role in regulating T-cell responses to cancer immunotherapy.

How cancer evades immune detection and destruction ?

Critical to cancer's survival and spread is its ability to evade the body's immune defenses. Starting in the 1990s, Sharpe and Freeman performed some of the critical early work that elucidated how cancer manages to do so.

The interplay between the immune system and the gut microbiota has been the focus of Kasper's work for many years. His lab has identified not only mechanisms of regulation but also specific microbial molecules and microbial enzymes responsible for modulating the immune system.

The notion that gut microbes could affect cancer immunotherapy is not entirely new. Recent studies have found tantalizing clues about the role that gut microbes play in immunotherapy treatment outcomes.

A new player enters the scene ;

In the new study, the researchers used mice whose colons were seeded with gut microbiota from patients with cancer. Some of those patients had responded well to immunotherapy, while others had not experienced much benefit. These animals' response to immunotherapy mimicked the treatment response in the humans whose gut microbes now lived in their intestines.


Read more - https://medicalxpress.com/news/2023-05-gut-boost-cancer-immunotherapy-power.amp