Hopes have today been raised for thousands of patients battling terminal breast cancer following a drug breakthrough.
Giving incurable patients a cocktail of three drugs can extend their lives by almost five months, a study found.
Results also showed 34 per cent of patients who took tucatinib alongside Herceptin and Xeloda did not see their disease get worse within a year.
In comparison, the rate was just 12 per cent for HER2 positive breast cancer patients given a placebo to take with the two drugs.
And the three-drug combination was proven to keep the disease at bay in patients whose tumours had spread to their brain, when it is incurable.
Researchers said more effective treatments are needed at this stage of cancer, and said tucatinib is a promising avenue.
Scientists found giving some breast cancer patients another medication to take alongside two existing drugs can extend their lives by almost five months
The findings were published in the prestigious New England Journal of Medicine.
HER2 positive breast cancer accounts for around one in five cases of the disease, which strikes 55,200 each year in the UK and 268,600 American women.
The tumours tend to be more aggressive than other types. An abnormality in the HER2 gene causes cells to grow and multiply at a rapid rate.
Survival rates are considered good – almost 100 per cent of patients diagnosed with breast cancer early are expected to live at least five years.
This drops to just 22 per cent in those at the metastatic stage, which isn’t considered curable. Treatment is used to extend life, but may stop working.
The trial involved patients across the globe, whose disease was advanced and had already been treated with multiple medicines.
The triple-drug combination includes trastuzumab (Herceptin), capecitabine (Xeloda) and tucatinib, an experimental drug
It was led by the Dana-Farber Cancer Institute in Boston, and involved clinics in the UK, such as The Royal Marsden NHS Foundation Trust.
In the first branch of the research, 480 patients were randomly assigned to receive either tucatinib, which has not been branded yet, or a placebo.
All of the patients were already taking both capecitabine (Xeloda) and trastuzumab (Herceptin).
The average length of time patients in the tucatinib group survived without their disease getting worse was 7.8 months.
In comparison, the placebo group lived for around 5.6 months before their disease progressed.
In the second arm of the study, Dr Eric Winer and colleagues looked at 291 patients whose cancer had spread to their brain.
Results showed the risk of death or disease progression was 52 per cent lower in the tucatinib-combination group.
After one year, 24.9 per cent of patients in the tucatinib-combination group had not seen their disease progress, compared to none given the placebo.
Overall, 45 per cent of patients in the tucatinib-combination group survived for two years after treatment – at an average of 21.9 months.
In contrast, the rate was just 26.6 per cent in the patients who were given a placebo – at an average of 17.4 months.
Side effects, such as diarrhoea, nausea, fatigue, vomiting, decreased appetite and headaches, weren’t considered too severe for those taking tucatinib.
Co-author Dr Alicia Okines, oncologist at The Royal Marsden NHS Foundation Trust, said the findings were significant because they showed ‘genuine benefit’.
She said: ‘We found tucatinib was more likely to shrink the tumour, and saw evidence that it was able to stem the progression of the disease for longer than in the placebo group. Most importantly it showed women who received the tucatinib lived a number of months longer.
‘Sadly many women with HER2 positive advanced breast cancer will see it spread to the brain during the course of their illness.
‘Usually this is treated with radiotherapy, sometimes requiring repeat treatments. There is however a limit to the amount of radiotherapy that can be safely delivered to the brain, and so we need more treatments that can penetrate brain disease more effectively.
‘In our trial we found that the combination of drugs with tucatinib was significantly effective at controlling the disease in the brain.’
A 59-year-old woman involved in the study praised the drug for keeping her cancer ‘in check’.
Linda, who didn’t share her last name, was diagnosed with the HER2 positive form of the disease in 2004.
Despite being in remission for 10 years following successful treatment, her cancer returned.
Linda, from Essex, was then offered the opportunity to go onto the trial at The Royal Marsden. So far, her disease has not progressed further.
She said: ‘Thankfully it’s kept my cancer in check. I still come in for regular scans and treatment, but otherwise have been able to get on with my life.’