High-Fiber Diet Enhances Immunotherapy Response, Study Finds

For some patients with melanoma, eating a diet rich in fiber could lead to an improved response to immunotherapy, according to findings presented at this year’s American Association for Cancer Research annual meeting.

A minority of patients — 20% to 30% — currently respond to checkpoint block- ade immunotherapy, said Dr. Christine Spencer, a research scientist at the Parker Institute for Cancer Immunotherapy. Her previous research shows that the gut microbiome — what she describes as the “trillions of microbes that live in your gut” — plays an important role in immune system regulation.

In the new study, Spencer and researchers from The University of Texas MD Anderson Cancer Center in Houston examined why some gut microbiomes were linked to a favorable response. Specifically, they wanted to know if diet influenced the gut microbiome and if that correlated with the patient’s response to immunotherapy.

Researchers collected surveys on diet and supplement use from 113 patients with melanoma being treated at MD Anderson. They profiled the diversity and type of bacterial species found in the patients’ microbiomes by analyzing fecal samples prior to therapy.

Preliminary data show that patients who reported eating high-fiber foods, including fruits, vegetables and whole grains, were about five times as likely to respond to anti-PD-1 immunotherapy.

Additionally, over 40% of patients reported taking probiotics before starting therapy. However, results showed that taking these supplements was associated with lower gut microbiome diversity, which was previously linked to a poor response to immunotherapy.