New breast cancer drug that can help 1 in 5 patients

‘A very exciting discovery’

MORE than 10,000 women a year could benefit from a powerful new breast cancer drug, a study suggests.

British scientists have spent 20 years creating drugs to shut down cancer cells’ defence mechanisms, killing them quickly without hurting healthy tissue.

The PARP inhibitors have been met with great excitement as early trials have shown they can extend women’s lives with few side effects.

But until now they were thought to benefit only between 1 and 5 per cent of breast cancer patients.

Now a major study by the Wellcome Trust Sanger Institute in Cambridgeshire suggests they may actually work for up to 20 per cent of patients. The finding was last night greeted as a watershed moment by experts. Scientists pre- viously thought PARP inhibitors would only work for women with a mutated BRCA gene, famously carried by film star Angelina Jolie.

She had a preventative double mastectomy in 2013, having lost her mother, grandmother and aunt to cancer. But the new research, published in the Nature Medicine journal, suggests they will also work for thousands of breast cancers similar to those with the BRCA mutation.

The first of these drugs – called olaparib – is already available on the NHS for women with ovarian cancer, and the first phase-three clinical trials are due later this year for breast cancer.

Study leader Dr Serena Nik-Zainal of the Sanger Institute said: ‘PARP inhibitors are important for quality of life because they specifically target cancer cells and so are well tolerated. I feel so strongly about the fact that one in five women might benefit from these drugs.

‘A lot of people who could be getting these treatments are not being offered them. This could change how clinical trials are designed in the future.’

The team, who analysed DNA from breast cancer tissue samples taken from 560 patients, found 22 had previously diagnosed BRCA 1 and 2 mutations. Another 55 had unexpected BRCA mutations, including some very unusual ones that were not inherited.

A further 47 had BRCA genes with no recognised mutations, yet in these patients the repair mechanisms controlled by the genes were still faulty. PARP inhibitors have been developed by researchers in Sheffield, Cambridge and London over the last 20 years.

They work by targeting the ‘Achilles’ heel’ of breast cancer, by attacking its defence mechanism.

Baroness Delyth Morgan, chief executive of the charity Breast Cancer Now, hoped the study ‘could now lead to a watershed moment for the use of mutational signatures in treating the disease’.

Jane Murphy, clinical nurse specialist at the charity Breast Cancer Care, called the findings ‘a very exciting discovery’ but cautioned ‘ there’s a long road ahead until we can get the complete picture’.

Breast cancer is the most common cancer among British women, with more than 55,000 diagnosed each year. Scientists are also trialling olaparib for cancers of the prostate, pancreas and stomach.