Hope for breast cancer patients who suffer heart woes from chemo: Scientists successfully predict who will – and discover an existing diabetes drug could offset the side effects
- 15% of people with aggressive HER2-positive tumors (found in around 66,000 US women a year) suffer side effects from their chemo
- The most effective chemo drug against HER2 tumors can cause heart woes
- Scientists discovered they could predict who will suffer these reactions by testing white blood cells drawn from patients
- They found the existing diabetes drug metformin could reboot heart cells to consume energy as they normally do
Scientists have discovered how to predict which breast cancer patients will suffer heart problems from chemotherapy – and how to prevent these side effects.
Around 15 percent of patients who take trastuzumab, used for a fifth of breast cancer cases, suffer heart issues, slowing their heart rate and sometimes leading to heart failure.
And yet, there are currently no methods to mitigate the debilitating and life-threatening reaction, short of quitting the drug.
Now researchers at the Stanford Cardiovascular Institute have found they can apply the drug to blood samples from patients first to see whether they are likely to suffer a reaction.
They also found that metformin, a drug already approved to treat diabetes, rejuvenated heart cells.
Fifteen percent of people with aggressive HER2-positive tumors (around 9,000 US women a year) suffer side effects from their chemo. A Stanford study found a way to predict and mitigate that
‘We could use this method to find out who’s going to develop chemo-related toxicity and who’s not,’ senior author Joseph Wu, MD, PhD, professor of cardiovascular medicine and of radiology and director of the Stanford Cardiovascular Institute, said.
‘And now we have an idea about the cardioprotective medications we can give them.’
Trastuzumab, sold under the brand name Herceptin, is the most effective chemotherapy drug used to fight HER2-positive tumors (diagnosed in about 66,000 US women a year), which tend to be more aggressive than other types.
The drug targets the gene HER2 in a bid to hamper, control and kill the tumor.
These types of tumors are rarely sensitive to treatment, meaning there are few alternatives to trastuzumab.
And yet it seems a number of patients have a genetic predisposition that causes a cardiovascular reaction.
Dr Wu and his team sought to find a way around it.
For their study, published today in the journal Circulation, they tested blood samples from three healthy women and seven with HER2-positive breast cancer – five of whom had had cardiac reactions to chemo.
They extracted the white blood cells and developed them into heart cells, then administered trastuzumab.
As hoped, they were able to see which cells reacted to the drug.
Crucially, they could see how the cells reacted.
It seemed that in those with heart issues from trastuzumab, their heart cells were not consuming energy properly, which slowed them down.
Dr Wu suggested that metformin, which controls sugar and energy in diabetics, could have a positive effect on these heart cells.
In their small study, they found that to be the case.
The team is now looking at data on breast cancer patients with diabetes who have used both drugs in conjunction to see if their findings hold true.
They hope that both the testing method and the remedy could one day be rolled out widely, to save sufferers from the ordeal and cut costs.
‘You can screen them in a dish first,’ Dr Wu said. ‘This will significantly cut the cost of drug development, providing better and more affordable drugs to the population.’