Cancer cells have a tendency to spread (or metastasise) to other sites in the body, forming secondary tumours. Once this has happened, the disease can be difficult to treat. In the next in our series of Expert Opinion interviews, Dr Powe discusses his plans to find out whether a common drug could stop cancer in its tracks.
Cancer Research UK: Why are you so interested in breast cancer spread?
Des Powe: Around a third of breast cancer patients develop metastasis but those patients account for 90 per cent of breast cancer-associated deaths. So, if you can stop the cancer spreading in the first place, you could save the majority of those patients from dying and improve their quality of life in the process. And really that’s what my study is about.
Cancer Research UK: Could you tell us about the background underpinning your work?
Des Powe: Our approach is based on how cancer cells migrate. In the early 1990s, laboratory studies showed that the stress hormone norepinephrine (also known as noradrenaline) could make cancer cells migrate or move. Norepinephrine sticks to a molecule on the cell surface called the ‘adrenergic receptor’ and if you block this receptor, you stop cell migration.
Fortunately, drugs that block the noradrenergic receptor are already on the market – they are called beta-blockers, and they’re commonly used to treat cardiovascular disease and anxiety. So the question that we set out to address was whether beta-blockers stop metastasis in breast cancer.
Cancer Research UK: And where are you now with your research?
Des Powe: In 2009, we performed an initial population study of around 500 women who had had breast cancer. We found that women who had already been treated with beta-blockers prior to their breast cancer diagnosis were 51 per cent less likely to develop metastasis. And they had a 71 per cent decreased risk of cancer-associated death, which was very encouraging.
Cancer Research UK: Could you tell us a bit more about the larger study?
Des Powe: The idea is that if beta-blockers can stop the formation of secondary cancers, the patient should do better. We’ll go through patient records for around 30,000 breast cancer patients looking at tumour recurrence and survival to see whether patients previously treated with beta-blockers live longer. We’d also like to understand the role of dosage and duration of treatment with beta-blockers and find out whether certain types of beta-blocker are more effective than others.
If these results confirm our previous findings, then there will be a very strong case for commencing clinical trials to test whether giving beta-blockers to women diagnosed with breast cancer can improve survival.
Cancer Research UK: How long do you expect this work to take?
Des Powe: We’re pushing to try and get it done in one year. I believe it’s very important so I want it done fast.
Cancer Research UK: How would you envision beta-blockers being used in the clinic?
Des Powe: Beta-blockers could be used as an ‘adjuvant’ therapy, meaning that they would support current treatments. You could potentially give beta-blockers to patients as soon as they are diagnosed and this might give protection against them developing secondary tumours.
Cancer Research UK: Beta-blockers are already in use so could they potentially reach patients faster than a completely new drug?
Des Powe: Yes. That should have a significant impact on the time spent in clinical trials.
Cancer Research UK: Is there any way of distinguishing patients that would respond to treatment with beta-blockers from patients who wouldn’t?
Des Powe: I would say that some of the most successful treatments for breast cancer are those that target specific molecules. The classic examples are Herceptin, which is targeted against HER2, and tamoxifen, which targets the oestrogen receptor.
So the patients whose tumours produce these receptors are, in theory, good candidates for receiving the targeted treatment and you’ve got a good reason to suspect that those patients will benefit from it. Beta-blockers neutralise adrenergic receptors, so you could identify the patients most likely to respond to them by testing whether their tumours produce these receptors.
Earlier this year, I found that tumours from around about 60 per cent of breast cancer patients produce one type of adrenergic receptor – the β2-adrenergic receptor. So theoretically, about 60 per cent of breast cancer patients could benefit from treatment with beta-blockers.
Cancer Research UK: You’re focussing on breast cancer in this study but could beta-blockers be used to treat other types of cancer?
Des Powe: Yes. Laboratory studies have shown that prostate, bowel and some types of lung cancer cells over-produce adrenergic receptors. This would suggest that these cancer types might respond to beta-blockers. But this will need to be confirmed.
Cancer Research UK: And finally, what inspires you most about your job?
Des Powe: I’ve always been interested in science and research is so challenging and exciting. I’ve always wanted to make an impact in fighting diseases – so it’s a reward coming into work!
Interview conducted by Safia Danovi, August 2011