Science Advances: Sugar Helps Cancer Hide from the Immune System, Discovery Could Change Immunotherapy

Scientists have identified a mechanism that allows cancer cells to evade the immune system and found a potential way to make them visible to the body again.

The study was published in the journal Science Advances.

Researchers found that tumor cells can create a protective “sugar coating” around themselves — a layer of carbohydrate-based molecules that prevents immune cells from recognizing and destroying them.

This protective layer, known as the glycocalyx, depends not only on the cancer cells themselves but also on their surrounding environment, known as the tumor microenvironment. It includes immune cells, blood vessels, connective tissue, proteins, and nutrients.

The scientists conducted experiments in which they grew cells under conditions designed to mimic different states of the body, ranging from soft, healthy tissue to the stiffer environment found inside tumors. They also varied glucose levels to investigate the effects of elevated blood sugar.

They found that excess glucose, combined with conditions characteristic of the tumor environment, caused cells to develop a thicker protective layer of carbohydrate molecules. This “sugar coating” helped cancer cells evade attacks by the immune system.

The researchers also identified a key role for the protein HSF1, which is involved in the cellular stress response. When this protein was absent, the ability of tumor cells to form the protective coating was reduced.

According to the researchers, drugs that block HSF1 could potentially “disarm” cancer cells and make immunotherapy more effective, particularly in metastatic cancer.

The findings may also help explain the link between high blood sugar, type 2 diabetes, and poorer outcomes in some cancer patients. Excess glucose may create conditions that give tumors an additional survival advantage.

At the same time, the researchers emphasize that the findings do not mean that sugar directly “feeds cancer.” Rather, the study identifies a biological mechanism through which metabolic disturbances may affect the ability of tumors to evade immune surveillance.

Further research will be needed to determine whether targeting HSF1 can improve cancer treatment and whether this approach can be safely translated into clinical practice.

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