For the first time, researchers have identified how a very aggressive form of breast cancer can escape one of the drugs considered to be the most effective in treating it.
In study published in the specialized journal Cancer Discovery, researchers at Massachusetts General Hospital (United States) have studied triple negative breast cancer (TNBC). This is difficult to treat because it does not have receptors for the hormones estrogen and progesterone, nor for the growth factor HER2, all three potential targets for treatment. When it reaches a metastatic stage, this type of breast cancer has a very poor prognosis.
The most effective treatment is sacituzumab govitecan (or SG, whose trade name is Trovdely), an antibody drug designed to specifically target breast cancer cells. Although more effective than chemotherapy alone, this drug sometimes faces resistance from TNBC.
Researchers report having identified two distinct alterations in the genome of TNBC cancer cells that allow them to develop resistance to this drug antibody.
While several resistance mechanisms have been demonstrated, all were linked to genetic modifications in metastatic tumor cells, which appeared after the primary tumor. It would therefore be during the appearance of metastases that triple negative breast cancer would sometimes become resistant to the drug.. We thus speak of acquired resistance, as opposed to an “innate” resistance, which would be present from the start.
This work could help improve the care of women with triple negative breast cancer, by adapting the treatment according to the genetic profile of the metastatic tumor cells. If resistance to the SG drug antibody is demonstrated, other therapeutic approaches should be attempted to better target tumor cells. With the long term, the hope of prolonging the survival of the patients.