Could antihistamines help fight cancer?

For those of you that suffer from watery, itchy eyes and runny noses throughout allergy season, antihistamines are likely to be your best friend. But a new study finds the drugs may do more than combat hay fever; they could fight cancer, too.

The research team, including Daniel H. Conrad, PhD, of the Department of Microbiology and Immunology at Virginia Commonwealth University, recently published their findings in The Journal of Leukocyte Biology.

Antihistamines are medication used to prevent or relieve symptoms of allergies, including hay fever, atopic eczema and reactions from insect bites and hives. The drugs work by stopping the release of histamine – a substance produced by the body that causes watery eyes, itching, sneezing, runny nose and breathing problems.

But the researchers found that as antihistamines do their job, they also interfere with the function of myeloid-derived suppressor cells – a type of cell known to hinder the body’s ability to combat tumors – meaning a new cancer drug candidate may be in the cards.

Antihistamines ‘reversed tumor-enhancing effects of myeloid-derived suppressor cells’

To reach their findings, the team analyzed two groups of mice. In one group, the researchers triggered a strong allergic response by infecting them with a rodent intestinal helminth, while the other group of mice had tumors.

The allergic mice were then injected with myeloid-derived suppressor cells and treated with one of two antihistamines – cetirizine or cimetidine. The mice with the tumors were also injected with the cells but were only treated with the antihistamine cimetidine.

The researchers found that in the allergic mice, the antihistamines reversed the effects of the myeloid-derived suppressor cells. However, in the mice with tumors, the antihistamine not only reversed the effects of the cells, but also reversed the increased tumor growth that the cells normally trigger.

The team also analyzed the blood of patients with and without allergies. They found that those with allergies – who usually have a higher release of histamine – had higher levels of myeloid-derived suppressor cells circulating in their blood.

According to the researchers, their study shows that antihistamines should be further investigated as a drug to target myeloid-derived suppressor cells.

Commenting on the team’s findings, John Werry, PhD, deputy editor of The Journal of Leukocyte Biology, says:

“Antihistamines may be one of the most commonly used over-the-counter drugs, but this report shows that we still have much to learn about their potential benefits.

It is certainly not yet time to prophylactically administer antihistamines for cancer prevention, but the more we learn about myeloid-derived suppressor cells, the more interesting these cells and their products become as immunotherapy targets in cancer. These new results suggest that we must be open-minded about seemingly distantly related immune mechanisms to examine.”