A breast cancer drug has been found to extend survival time for more women, raising the prospect of its use being extended for 17,000 women on the NHS.
Enhertu, manufactured by AstraZeneca, is currently available to around 400 women in England with advanced breast cancer, and previous trials showed it reduced the risk of disease progression or death by 72 per cent.
But experts have identified a new subset of breast cancer patients - representing 16,800 women in the UK - who would also benefit from the treatment.
The drug is used for patients with metastatic breast cancer, meaning it has spread, and who are classed as HER2-positive - a type of protein that helps cancer cells to grow and survive.
Around 35,000 people are living with metastatic breast cancer in the UK. Some 80 per cent are categorised as HER2-negative, but of those up to 60 per cent (16,800) express low levels of HER2.
Latest results published
The latest results of AstraZeneca's DESTINY trial, assessing the efficacy of Enhertu, were presented on Sunday at the American Society of Clinical Oncology’s (ASCO) conference in Chicago.
Some 557 HER2-low patients, from Asia, Europe and North America, were enrolled in the trial and had already been treated with at least one round of chemotherapy. One group was assigned Enhertu, while the other was given standard chemotherapy.
Enhertu, which is administered intravenously every three weeks, resulted in a 49 per cent reduction in the risk of the cancer progressing and a 36 per cent cut in the risk of death, compared to those who received standard treatment.
The overall survival time for patients increased from 17.5 months to 23.9, and the time during which the tumour growth was stable or shrunk nearly doubled from 5.4 months to 10.1 months.
Dr Susan Galbraith, who leads Oncology Research & Development at AstraZeneca, said the drug could be available on the NHS as soon as next year, following a successful NICE review.
Seeking regulatory review
She confirmed the firm had asked the regulatory body to review the drug for this new cohort of patients.
Last year, the National Institute for Health and Care Excellence (NICE) recommended Enhertu, also known as trastuzumab deruxtecan, for HER2-positive patients who are not eligible for surgery or who have already tried two or more treatment options.
Around 400 people in England were immediately eligible for the treatment on the Cancer Drugs Fund (CDF). NICE has said it will use these latest findings when it reassesses the drug’s effectiveness, following its period on the CDF.
Charles Swanton, chief clinician at Cancer Research UK, said these DESTINY results could pave the way for Enhertu to be extended to thousands more patients.
“I would anticipate this study could well form the basis for future approvals to extend its use to HER2 low breast cancers for more patients,” he said.
New category of patients
Speaking at the world’s largest cancer conference, Dr Jane Lowe Meisel, ASCO expert in breast cancers, said the findings would “redefine how we classify breast cancer” by creating a new category of patients; HER2-low.
HER2-low is not currently defined as a type of breast cancer in the UK, but scientists from the Memorial Sloan Kettering Cancer Centre, New York, who led the research, are now calling for it to be officially recognised.
AstraZeneca also confirmed other ongoing trials are assessing the use of Enhertu for early stage breast cancer, which could increase cure rates in these groups.
Other research is also underway to trial the drug in lung and stomach cancer.
“I do think that the principle of these antibody drug conjugates, a technology that delivers the cell killing mechanism directly to the cancer cell, is something that can extend across multiple different cancers with multiple different targets,” Dr Galbraith said.
“This new technology can be applicable to really quite a large patient population [and] that's exciting promise for the future.”
Looking at new ways to fight cancer
Dr Kotryna Temcinaite, senior research communications manager at Breast Cancer Now, said: “With an estimated 35,000 people living with secondary (metastatic) breast cancer in the UK, we urgently need to find new ways to treat this devastating disease.
“It’s hugely exciting trastuzumab deruxtecan [Enhertu], which is already being used on the NHS to treat some women with HER2-positive secondary breast cancer, may benefit even more breast cancer patients giving them the hope of additional precious time with their loved ones.
“This treatment must now be promptly submitted for licensing, and assessed for use on the NHS, so this different group of eligible women have the chance to benefit from it as soon as possible.”