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.