PR: Better breast cancer treatment decisions through genetic testing

22.06.2016

I'm sharing insights from genetic testing and cancer experts. Today, we hear from Professor Laura van ‘t Veer, developer of an award-winning genetic breast cancer test.

The importance of early detection and genetic testing

Breast cancer is the most common form of cancer among women. Every year, more than 1.7 million women worldwide are affected by the disease and, according to the World Health Organization450,000 of them do not survive. Treatments have improved throughout the years, but even when a tumor is successfully removed the chance of recurrence still exists. Prof. Laura van ‘t Veer and her team at Agendia have developed the MammaPrint test to help doctors identify this chance of recurrence and make better treatment decisions. In this interview, Laura discusses how MammaPrint was developed and how the test can prevent chemotherapy over treatment in one third of patient cases.

Professor van ‘t Veer, can you tell us more about yourself and what inspired you to choose this career path?

I am a molecular biologist and I chose to study biology because I was interested in the development of human beings, and specifically tissues in the human body. Through this interest, I developed a focus on cancer research. I started working in this field almost 30 years ago. In the mid-nineties, I was offered a position at the Netherlands Cancer Institute to start the department of Molecular Pathology. My task would be to translate new and existing research findings into solutions for patient care. Breast cancer was a high priority topic at the institute and it fitted with my personal research interests, so I decided to focus on testing new methods that could increase the accuracy of diagnosis.

How was the MammaPrint test developed and which unmet medical need were you trying to address?

We started research for the MammaPrint test in the year 2000. By then, it was well known that women who have been diagnosed with breast cancer have either late, early or no recurrence at all. The problem is that most patients are treated with chemotherapy, even if they have a low risk of recurrence. Out of 100 patients, only 25–30 will likely develop a recurrence. Yet, depending on the local guidelines up to 60–90% of these women will probably receive chemotherapy. This means there is a lot of over treatment. We wanted to develop a test that would help doctors risk-stratify their patient group to guide the use of this therapy.

To do this, we decided to take tissue from women who had been diagnosed with cancer. We focused on women aged below 55 as we knew that for these women, the cancer tends to be more aggressive. These younger women also have a longer life expectancy. Therefore, we wanted to know what the best treatment for them would be in order to reduce the chance of recurrence.

We analyzed 25,000 genes from each tumor sample and we identified an activity pattern in the tumors that would allow us to distinguish between high risk and low risk cases. There are 70 cancer-specific genes active in these tumors, and we learned that we can predict the risk or recurrence by evaluating if the genes are switched on or switched off. If the genes are switched on, the tumor is very aggressive. It invades the surrounding tissue and can give rise to metastasis in other organs. If those 70 genes are switched off, the tumor remains in its place and there is not much risk of recurrence. Patients who have a negligible risk of recurrence would only suffer needlessly from the side effects of chemotherapy. The test results can spare them this rigorous and life-altering process. So far, the use ofMammaPrint has proven to reduce over treatment with chemotherapy in 20–30% of patient cases.

Can you explain your research in more detail and how it compared to other clinical trials?

Our initial study where patients took MammaPrint into account for their actual treatment, looked at 427 patients diagnosed between 2004–2006 in the Netherlands. Their clinical diagnosis took the following into account to determine the risk of recurrence:

1. The age of patients

2. Tumor diameter

3. Number of dividing cells

4. Presence of estrogen receptor in the tumor

We looked at the genes of the tumors themselves for recurrence indicators. When we delivered the results we had a discordance of 30% between the clinical and the MammaPrint diagnosis. Two thirds of these patients decided to forgo chemotherapy based on the MammaPrint results and 98%of these women had no recurrence without taking chemotherapy. These were excellent results.

Currently, we are working on a 5-year study on 7,000 patients. The trial randomizes the use of MammaPrint with a clinical-pathological assessment for chemotherapy. It is the only trial of its kind at such a scale. The study will help us identify if we can be even more selective with treatments using the MammaPrint test. So far, we anticipate that 20–30% will be able toforgo chemotherapy when following MammaPrint without jeopardizing their outcome. The results of the test will be available soon.

How does MammaPrint compare to other tests in the market?

There are two tests available in this area of risk prediction, MammaPrint and Oncotype, which is commercialized by Genomic Health. The biggest difference between them is the approach that was used to develop them. The developers took knowledge from the existing medical literature, selected 16 genes that could predict recurrence and put it all together in one test. The test trial was done in women who had 5 years of endocrine treatment.

MammaPrint, however, looked at all 25,000 genes in tumor cells. These cells have different behavior, so we could compare how normal and invasive cells behave. We used an approach to get to the gene activity pattern associated with aggressive versus low risk recurrence. In addition, we tested it on women who had not received drug interventions.

How do you score the robustness of the test? What is the chance that it can deliver an inaccurate result?

MammaPrint has met all quality criteria in the European Union and theUnited States. It is the first test of its kind with FDA clearance. If you repeat the test, the results will be 99% identical, the chance that something technical can go wrong is below 1%.

Patients with a late recurrence risk (after 15 years), who have slow growing tumors might have a bigger chance of error. We are working on adding more information about patients with late recurrence risk to reduce this error margin. However, it is already known that these patients do not benefit from chemotherapy.

So far, 50,000 women worldwide have used the test. What are the obstacles you face for more widespread adoption?

There are three main obstacles for adoption:

1. Reimbursement by insurance companies — this is a general problem that is not only true for us. Insurance committees have different requirements to agree on reimbursement and this remains a very inefficient and time-consuming process. At the moment, most insurance companies in the Netherlands and Germany reimburse the test and ⅔ of insurances in the US do as well. In other countries, MammaPrint is reimbursed on a case by case basis depending on the country and the patient’s insurance company.

2. Guidelines — tests like ours are considered an option for now. They are considered a standard for some, but not all.

3. Changing clinical practice — we are changing the way physicians think and introducing a new way of testing. We’ve come a long way but even the standards of care and pathology assessments vary depending on the doctor or clinic, so the road to adoption is not without its challenges.

What is your vision for the future of the MammaPrint test?

My vision is that the test will become a standard so we can guide doctors to make more informed and accurate treatment decisions.

We also want to combine MammaPrint with tests that indicate which specific biology is defective in a certain tumor to choose the right drug more effectively. This is currently in development in clinical trials.

About Professor van ‘t Veer

Professor van ‘t Veer is Agendia’s Co-Founder and Chief Research Officer. As one of the world’s leading innovators in cancer diagnostics, she is widely recognized as a pioneer in the field of personalized medicine. She has a 20-year track record in molecular oncology research and recently won the European Inventor Award for her impact on breast cancer diagnostics.

Article last time updated on 22.06.2016.

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