Patients with HR+ and HER2- node positive high-risk early breast cancer experience improved long term overall survival seven years on, following two years of taking a targeted drug alongside standard hormone therapy, according to new research.
The seven-year data from the international monarchE trial was simultaneously published in Annals of Oncology and presented at the European Society for Medical Oncology 2025 Congress by Professor Stephen Johnston, Head of the Breast Unit and Consultant Medical Oncologist at The Royal Marsden NHS Foundation Trust and Professor of Breast Cancer Medicine at The Institute of Cancer Research, London.
The monarchE Phase III trial examined whether adding a targeted drug called abemaciclib to standard hormone therapy could reduce disease recurrence and improve the overall survival rate for women with hormone receptor-positive (HR+), human epidermal growth factor 2-negative (HER2-), node-positive, high-risk early breast cancer.
Statistically significant reduced risk of death
The data presented showed patients who took adjuvant abemaciclib and hormone therapy combined had a statistically significant and clinically meaningful 15.8 per cent reduced risk of death compared to those patients who received hormone therapy alone.
Additionally, fewer patients in the abemaciclib arm of the trial developed, or were living with, metastatic disease compared to those in the hormone therapy only arm. 32 per cent fewer patients treated with abemaciclib combined with hormone therapy were living with metastatic disease compared to those receiving hormone therapy alone (6.4% versus 9.4% respectively). Continued long term follow up will determine if this translates into further improvements in overall survival.
Approximately 70 per cent of breast cancer patients have HR+ and HER2- tumours, and of those a proportion of patients will have a higher risk of relapsing in the first two years. Patients with disease that has spread to lymph nodes, with either a large size or high grade of tumour were considered to be at ‘high-risk’ of recurrence and recruited to the study.
"It is wonderful to see patients able to live their lives fully"
"The most recent data from our monarchE study reaffirms that this is the first medicine in over two decades to deliver a clear improvement in overall survival for patients in the adjuvant setting," said Professor Stephen Johnston, Head of the Breast Unit and Consultant Medical Oncologist at The Royal Marsden NHS Foundation Trust and Professor of Breast Cancer Medicine at The Institute of Cancer Research.
"It is wonderful to see these patients in my clinic who continue to remain disease free and are able to live their lives fully."
The monarchE trial was funded by Eli Lilly and Company. Breast cancer research at The Royal Marsden NHS Foundation Trust is funded by The Royal Marsden Cancer Charity and National Institute for Health and Care Research (NIHR).