DNA testing helping to personalise breast cancer treatment

Dr Francis Hunter. Photo / Doug Sherring

Patients battling advanced breast cancer could avoid wasting time on needless treatments with the latest DNA sequencing technology helping to identify genes that reject drugs.

"If we can understand the way in which cells are changing to become resistant to treatment then that provides us with an opportunity to do something about it," said University of Auckland research fellow Dr Francis Hunter.

Hunter, who spoke at the Queenstown medical research conference this week, has been examining a new drug called Kadcyla.

The drug has been approved to treat New Zealand women with advanced HER2+ cancer but was not yet publically funded.

Clinical trials showed that about 44 per cent of tumours shrank when treated with Kadcyla and on average patients survived for seven months longer.

Hunter said one of the biggest challenges with the drug was, while it worked initially, in virtually every patient the cancer started to grow again.

Using the DNA-sequencing technology, his team have systematically been screening all 20,000 genes one-by-one to identify which genes were important to controlling how sensitive those cells were to rejecting treatment.

"We found that about 600 genes - which is about 3 per cent of all human genes, which is a large number - may have some role in causing resistance to the drug."

The next stage was testing those lab findings to see if the same results applied in women using the treatment.

Roche - the drug company of Kadcyla - has provided $30,000 over the next year to get a clinical study underway.

Tissue samples will be collected from women at the beginning of their treatment and after they develop resistance.

Through a molecular analysis, researchers will observe whether the changes were the same as what was occurring in the lab.

"If it is, then that gives us a clear signal that we are moving down the right track."

Hunter said the next follow up was essentially finding more effective treatments for women with advanced HER2+ cancer.

"This could include combination therapies, so combining drugs that prevent resistance mechanisms that we identified or developing new therapies that employ related but different chemicals that would again avoid resistance.

"In New Zealand, a low portion of patients use Kadcyla because it's still only available privately, overseas it was being used widely.

"Part of the reason why it remains in the private realm was because the benefit is limited by the emergence of resistance, so if we can avoid that or reverse it then that puts the drug in favour of providing greater access."

What is breast cancer?

Breast cancer is the result of abnormal gene "mistakes" or mutations, which are usually acquired over time as we age. These mutated cells grow and multiply in an uncontrolled way.

Breast cancer in New Zealand

• Most common cancer for women in New Zealand with 3000 new diagnoses each year.

• Around 600 New Zealand women die from breast cancer every year.

• Around 70 per cent breast cancers are diagnosed in women over the age of 50.

• Around 90 per cent of people diagnosed have no breast cancer in the family.

• Māori and Pacific women at greater risk of dying from breast cancer.

About Dr Francis Hunter:

The 33-year-old graduated from the University of Auckland with a BSc and Honours in Biomedical Science.

He completed his PhD at the University of Auckland in December 2014 and gained a place on the Dean's List for the excellence of his doctoral research.

In 2014, he won the global Breast Cancer Startup Challenge from nearly 700 entries.

In 2015, he was a member of the international winning team in the Merck Serono Innovation Cup in Darmstadt in Germany where he was selected as one of 30 finalists, from a pool of 850 entries.

His proposal was chosen as the overall winning concept for the Merck Serono Innovation Cup, sharing the €20,000 prize and trophy among the winning team.