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9th April 2018

New Strategy to Beat Therapy Resistant Breast Cancer

Associate Professor Theresa Hickey   breast cancer

Estrogen receptor positive breast cancer is the most common breast cancer to affect our community, making up 75 per cent of all diagnoses of this devastating disease. Thanks to the support from our donor community, women diagnosed with this breast cancer do have a targeted treatment available to them to help beat their disease.

Unfortunately, many patients develop resistance to this targeted treatment, and without access to any other treatment options, they can only undergo chemotherapy.

Now armed with funding from Australian Breast Cancer Research, Dr Theresa Hickey from the Dame Roma Mitchell Cancer Research Laboratories at The University of Adelaide is pioneering vital research to better understand why patients develop therapy resistance in the hope of coming up with new treatment options to combat this fatal form of the disease.

We believe that breast cancer represents a state of hormone imbalance and are exploring whether restoring this balance will be an effective, less toxic way of treating or prevention estrogen receptor positive breast cancer.

Estrogen receptor positive breast cancer occurs when the cancer cells grow in response to the sex hormone estrogen. These cancers also commonly have other sex hormone receptors, including androgen and progesterone receptors.

“Breast cancers that have all three sex hormone receptors are much more likely to respond to anti-estrogen therapy than those that have estrogen receptor alone. Those that have estrogen receptor and just one other sex hormone receptor lie in between these extremes in terms of therapy response,” Theresa said.

“We know that the major cause of death from breast cancer is resistance to current estrogen receptor target therapies, so through our research we are developing alternative approaches to treat or prevent therapy resistant disease.”

To develop these alternative therapies, Dr Hickey and her team first had to understand the hormonal imbalance that occurs within breast cancer to decipher how to target this with a potential treatment.

“The sex hormones estrogen and androgen are natural antagonists in men and women, and their relative action dictates biological gender and sex differences in the functioning of many body organs. The breast is an excellent example of sex hormone antagonism as breasts develop in women due to a predominance of estrogen action and do not develop in men due to a predominance of androgen action.

We aim, through a new therapy, to reawaken androgen receptor activity in estrogen receptor positive breast cancers to stimulate its ability to control the actions of estrogen and in turn prevent breast cancer from forming or treat it once it has developed.

“Since estrogen receptor positive breast cancer is driven by abnormal estrogen activity, we suspect the androgen receptor is not able to play its normal role to keep the balance in check.”

Continuing to explore the role of these receptors in estrogen driven breast cancer, Dr Hickey’s research will open up avenues for repurposing drugs currently in use for other diseases in the hopes of beating the most aggressive breast cancers affecting our loved ones.