Israeli researchers now know why 60 percent of patients with metastatic melanoma do not respond to immunotherapy.

After examining tumors of 116 patients using proteomics, the researchers found the non-responding patients tended to have lower fatty acid metabolism, meaning that their enzymes broke down fat for energy at a slower rate. Their findings appear in Cell.

Oncologists can now check the levels of fatty acid metabolism in their melanoma patients and advise those who have high levels to pursue immunotherapy. Researchers say it may also be possible to raise the levels of fatty acid metabolism in cancer cells with medication to make more patients receptive to immunotherapies. 

The study was conducted by a team of researchers led by Prof. Tami Geiger, Dr. Michal Harel and Prof. Gal Markel of Tel Aviv University’s (TAU) Sackler School of Medicine and Sheba Medical Center’s Ella Lemelbaum Institute for Immuno-Oncology.

"In recent years, a variety of cancer immunotherapy therapies have been used, therapies that strengthen the anti-cancer activity of the immune system," explains Markel, a senior oncologist and scientific director of the Ella Lemelbaum Institute at Sheba Medical Center, Tel HaShomer in a news release. "These treatments have been shown to be highly effective for some patients and have revolutionized oncology. However, many patients do not respond to immunotherapy, and it is critical to understand why.” 

 "In our study, we identified a significant difference between melanoma patients who live years thanks to immunotherapy and patients who are not at all affected by the treatment," adds Geiger, head of Tel Aviv University’s Proteomics Lab.