A drug that’s already approved to treat certain ovarian cancers holds some advanced breast cancers at bay longer than standard chemotherapy, according to results from a clinical trial.
Tumours shrank in about 60% of women who received the targeted drug, called olaparib (Lynparza), compared with 29% of those who received chemotherapy.
The OlympiAD trial also found that women who took olaparib, a type of drug called a PARP inhibitor, experienced fewer side effects and had a better quality of life than those given standard chemotherapy.
Results from the trial were presented at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago in the US, and are published in the New England Journal of Medicine.
“This is the first demonstration of improved outcomes with a PARP inhibitor compared to standard treatment in women with BRCA mutation-associated breast cancer,” said Dr Mark E. Robson, clinic director of the Clinical Genetics Service and medical oncologist at Memorial Sloan Kettering Cancer Center in New York, who led the study.
Dr Jean Abraham, a breast cancer expert from the Cancer Research UK Cambridge Centre, said the results “paved way for the possibility of new treatment options” for these women.
The women who took part in the trial had breast cancer that had spread and was caused by faults in the BRCA genes, which olaparib is designed to target.
Their breast cancer cells also either had to have one of two hormone sensing molecules on their surface or be free from these molecules along with the HER2 molecule, so-called ‘triple negative’ breast cancers.
The 302 women who took part in the phase III trial had all previously received standard treatment for their disease, including chemotherapy and hormone therapy. These women were then given either the standard treatment at this advanced stage – a single chemotherapy drug – or olaparib.
The researchers found that it took significantly longer for the disease to get worse in those given olaparib – 7 months for olaparib compared to 4.2 months for standard chemotherapy.
This meant that women given olaparib had a lower risk of their disease worsening than those given standard chemotherapy. Women treated with olaparib also experienced fewer side effects than those treated with standard chemotherapy.
“[Olaparib] helps preserve patient quality of life, offers the chance to postpone the need for I.V. chemotherapy, and avoids side effects like hair loss and low white blood cell counts,” said Robson.
It’s too early to know if the benefit seen with olaparib will ultimately lead to these women surviving longer. But since these patients have few treatment options other than chemotherapy, Abraham said the results are an “important step forward in finding targeted drugs for this type of breast cancer”.
“The study suggests that olaparib is more effective and causes fewer side effects than treatment with a single chemotherapy drug for these patients,” she added.
“The challenge now will be to identify whether olaparib can be used in patients with early breast cancer, either with chemotherapy or after chemotherapy, to prevent their disease from spreading.
“There are already two trials looking at these questions, one – PARTNER, which is co- supported by Cancer Research UK – will also help us to understand if olaparib can be used more widely than just for breast cancer patients with BRCA faults.”
Professor Arnie Purushotham, Cancer Research UK’s senior clinical adviser, described the results as “encouraging”.
“Cancer Research UK scientists have been closely involved in the development of olaparib, from the earliest discoveries through to clinical trials to test the drug,” he added.
The OlympiAD trial was funded by AstraZeneca.
Robson, M., et al. (2017) Olaparib for Metastatic Breast Cancer in Patients with a Germline BRCA Mutation. NEJM. DOI: 10.1056/NEJMoa1706450