The phase 3 trial, which compared Enhertu’s performance against trastuzumab emtansine as a treatment for HER2-positive metastatic breast cancer, involved around 500 patients at multiple sites in Asia, Europe, North America, Oceania and South America.
AstraZeneca said nearly all patients treated with Enhertu were alive after 12 months (94.1 per cent) compared to 85.9 per cent of patients treated with trastuzumab emtansine (T-DM1).
A new breast cancer drug reduces the risk of death or disease progression by 72 per cent compared to an existing treatment, AstraZeneca has announced.
The British pharmaceutical firm said the results of its trial of Enhertu were “groundbreaking” and showed “a strong trend towards improved overall survival.”
However AstraZeneca warned that the analysis is “not yet mature and is not statistically significant”.
Susan Galbraith, executive vice president of Oncology R&D at AstraZeneca, said: “Today’s results are ground-breaking.
“These unprecedented data represent a potential paradigm shift in the treatment of HER2-positive metastatic breast cancer, and illustrate the potential for Enhertu to transform more patient lives in earlier treatment settings.”
Javier Cortes, from the International Breast Cancer Centre in Barcelona, said patients with previously treated HER2-positive metastatic breast cancer will typically experience disease progression in less than a year with available HER2-directed treatments.
He said the the “high and consistent benefit” seen across efficacy endpoints and key subgroups of patients receiving Enhertu is “remarkable and supports the potential of Enhertu to become the new standard of care for those who have previously been treated for HER2-positive metastatic breast cancer”.
Ken Takeshita, global head of R&D at Daiichi Sankyo, said: “These landmark data will form the basis of our discussions with global health authorities to potentially bring Enhertu to patients with previously treated HER2-positive metastatic breast cancer as a more effective treatment option as soon as possible.”
While breast cancer survival rates have doubled over the last four decades in the UK, every year around 11,500 women and 85 men die from the disease.