American scientists describe how estrogen reduces the immune system’s ability to attack tumors, but also reduces the effectiveness of immunotherapies used to treat triple-negative breast cancers.
- Estrogens contribute to increased tumor growth in estrogen receptor-negative breast cancer tumors.
- Antiestrogen drugs reversed the effects of estrogen and restored the power of immunotherapies.
- One of them, which is called “lasofoxifene”, will be tested in women suffering from triple negative breast cancer.
Estrogens are known to promote tumor growth in breast cancer cells that carry their receptors. However, a new study, published in the journal Science Advancesshows that these hormones produced by the ovaries are also involved in the growth of tumors lacking receptors, as well as in many other cancers.
Estrogen promotes the growth of breast tumors
To reach this conclusion, researchers at Duke University (United States) focused on a type of white blood cells, called “eosinophils”, which are generally activated during allergic reactions and inflammatory diseases. Recently, eosinophils have been identified as being important in tumors. “Peripheral eosinophilia and tumor-associated tissue eosinophilia (or TATE) predict improved response to immune checkpoint blockade in breast cancer” and therefore better results in patients also suffering from colon, esophagus, stomach, oral, melanoma and liver cancers.
In their work, the team reports that in mice with estrogen receptor-negative breast cancer and melanoma, estrogen decreased the number of peripheral eosinophils and tissue eosinophilia, which contributed to increased tumor growth. . Conversely, antiestrogen therapies inhibit estrogen receptor signaling and enhance the effectiveness of immunotherapies, thereby slowing tumor growth.
Triple negative breast cancer: an anti-estrogen drug tested soon
“These results highlight the importance of estrogen receptor signaling as a regulator of eosinophil biology and TATE and highlight the potential short-term clinical application of anti-estrogen drugs to augment the benefits of immunotherapies in multiple types of tumors”, declared Donald McDonnellprofessor in the departments of medicine, pharmacology and cancer biology, who led the research.
According to the authors, clinical trials are planned with an experimental anti-estrogen drug called “lasofoxifene.” The latter will be tested on patients suffering from triple negative breast cancer.
