Delicious Mediterranean Appetizer from directly above.
Credit: Nazar Abbas Photography/Getty Images

Eating a Mediterranean diet, rich in fiber, mono-unsaturated fatty acids and polyphenols, has been associated with improved immunotherapy response rates and progression-free survival in advanced melanoma patients, a new study presented today at UEG Week 2022 has found.

Experts anticipate that diet will play a role in the success of immunotherapy and trials are being expanded to investigate outcomes for different tumor types, including digestive cancers.

A Mediterranean diet, containing mono-and polyunsaturated fats from olive oil, nuts and fish, polyphenols and fiber from vegetables, fruit, and whole grains, was significantly associated with an improved response to immunotherapy drugs called Immune Checkpoint Inhibitors (ICIs). ICIs, which have been highly successful in treating melanoma, work by blocking immune system checkpoints, which then force the body’s own T-cells to attack cancers.

The new multi-center study by researchers from the UK and the Netherlands, recorded the dietary intake of 91 patients with advanced melanoma, who were treated with ICI drugs and monitored their progress with regular radiographic response check-ups.

“The gut microbiome has been previously shown to be associated with the response to treatment with immune checkpoint inhibitors,” Laura Bolt, an MD/PhD candidate in the Department of Gastroenterology and Hepatology at the University Medical Center Groningen, told Inside Precision Medicine.

“Interestingly many of the identified bacteria have a role in the degradation of fiber and starch and synthesis of short-chain fatty acids that are known for their wide effects on the immune system. Given this role, the hypothesis arose that diet, especially a high fiber diet, is associated with response via its effects on the gut microbiome. This has already been demonstrated by 2 studies for fiber intake,” she added.

Studies linking overall diet composition beyond specific nutrients to treatment response were yet lacking from the literature. This group performed dietary pattern analyses and found that the Mediterranean diet was associated with response to immune checkpoint inhibitors.

As well as having a significant association with overall response rate, a Mediterranean diet was significantly associated with progression-free survival at 12 months.

Said Bolt: “ICI has helped to revolutionize the treatment of different types of advanced cancers. Our study underlines the importance of dietary assessment in cancer patients starting ICI treatment and supports a role for dietary strategies to improve patient outcomes and survival.”

The study also found that eating whole grains and legumes reduced the likelihood of developing drug induced immune-related side effects, such as colitis. In contrast, red and processed meat was associated with a higher probability of immune-related side effects.

“The relationship of ICI response with diet and the gut microbiome opens a promising and exciting future to enhance treatment responses. Clinical trials investigating the effect of a high fiber diet, ketogenic diet and supplementation of omega-3 are underway. Since ICI therapy is being expanded to various tumor types, including digestive cancers, these studies could unlock treatment benefits for a large group of cancer patients in the future,” Bolte noted.

She added that, “It is known that Mediterranean diet high in plant-derived foods, fiber and unsaturated fats from plant oils, nuts and fish, is associated with gut bacteria that have been linked to immunotherapy response. Therefore, there might be a potential for dietary modulation of the gut microbiome, which affects the immune system, in turn improving immunotherapy response.”

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