Obesity and cancer: new data
Obesity increases the effectiveness of cancer immunotherapy
Sergey Kolenov, Hi-tech+
Overweight is considered one of the main factors in the development of cancer, second only to smoking. However, a new study shows that the relationship between obesity and cancer may be more complicated than previously thought.
One of the promising approaches to cancer treatment is immunotherapy using checkpoint inhibitors. This Nobel Prize-winning technique is based on blocking the PD-1 protein, which is located on the surface of immune T cells. The tumor activates this protein to weaken the immune response.
Drugs that disable this molecular brake allow T-lymphocytes to attack cancer cells. In experiments, checkpoint inhibitors led to the destruction of incurable skin and lung tumors. However, unfortunately, not all patients respond to immunotherapy.
In an attempt to find out what determines the success of immunotherapy, oncologists have revealed an unusual pattern: it turned out that this technique gives better results in obese patients.
A group of researchers from the University of California, whose work is described by the UC Davis Health Obesity press release both feeds tumors and helps immunotherapy kill cancer, confirmed this observation in the laboratory and found a possible explanation for it. Experiments with mice have confirmed that in obese animals, tumors grow faster, and T-cells work worse. Among other things, there is more PD-1 protein on their surface, which increases the possibility of the tumor to turn off the immune response. According to the researchers, an excess of PD-1 is associated with an increased content of leptin, a hormone that is produced by adipose tissues.
In general, obesity increases the risk of cancer, but a large amount of PD-1 paradoxically increases the sensitivity of T-lymphocytes to checkpoint inhibitors. "Taken off the brakes", these cells strenuously attack the tumor, which is further facilitated by glucose and other nutrients stored in adipose tissue.
The unexpected beneficial effect of obesity should not be misleading, the researchers note. In general, the harm of being overweight far exceeds the possible benefits.
In order to use the discovery in cancer therapy, experts intend to study whether it is possible to simulate the detected phenomenon with a high-fat diet and an artificial increase in leptin levels. In addition, it is necessary to analyze how other factors, such as age and gender, affect the detected effect.
Article by Wang et al. The paradoxical effects of obesity on T cell function during tumor progression and PD-1 checkpoint blockade is published in the journal Nature Medicine – VM.
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