Although breast cancer survival rates are overall very high, some forms of cancer are more difficult to treat than others. However, a new compound proves highly effective against these types by targeting a protein that makes cancer cells resistant to treatment.

Triple negative breast cancer is often resistant to treatment. Its name refers to the hormone receptor status that divides breast cancer into different types, and the cells in this type of cancer are called triple negative because they do not have estrogen receptors, progesterone receptors, or the protein HER2.

Triple negative breast cancer tumors can be particularly aggressive, and they tend to occur in women with a defective BRCA1 gene.

It is estimated that approximately 12 percent of breast cancers are triple negative.

New research, which has recently been published in the journal Science Translational Medicine, tests the effect of a novel anticancer agent on treating different types of breast cancer and finds that a new compound - when administered in combination with conventional anticancer drugs - is "highly effective" for treating both triple negative and HER2 positive breast cancers.

As the authors of the new study note, treatment for triple negative breast cancer has seen little improvement in the past 30 years, so the recent findings are particularly welcome in this context.

The researchers were led by Dr. Delphine Merino, Dr. James Whittle, Dr. François Vaillant, Prof. Jane Visvader, and Prof. Geoff Lindeman, all of whom are from the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia.

Compound targets cancer's 'Achilles' heel'

Dr. Merino and colleagues combined existing anticancer drugs with a new compound called S63845. The uniqueness of the new compound lies in the fact that it targets MCL-1, which is a protein that has previously been shown to be key for the survival of cancer cells.

"MCL-1 gives cancer cells a survival advantage, allowing them to resist chemotherapy or other anti-cancer therapies that would otherwise trigger cancer cell death," explains Dr. Whittle. This advantage has been referred to by the researchers as "Achilles' heel."

As the authors explain in the study, MCL-1 is often overexpressed in breast cancer patients, and high expression usually means poor life expectancy for the patient.

In the new research, Dr. Merino and team tested the effect of the MCL-1 inhibitor in cancer cell cultures, as well as in tissue samples taken from breast cancer patients who had high levels of MCL-1.

Dr. Vaillant explains the methodology used, saying, "With the support of the Victorian Cancer Biobank, and samples donated by breast cancer patients, we have generated a large number of laboratory models that mimic how tumors behave and respond to therapy in the patient, allowing us to test a range of anti-cancer drugs."

S63845 worked together with existing drug docetaxel to combat triple-negative breast cancer, and with the drugs trastuzumab or lapatinib to inhibit HER2-positive breast cancer.

"Combining S63845 with standard therapies, such as chemotherapy or targeted drugs such as Herceptin [trastuzumab], proved highly effective in killing these very aggressive tumor types," says Dr. Merino.

Dr. Whittle also stresses the advantages of combining the new compound with existing treatment.

Medical News Today