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Addition of abemaciclib to hormone therapy reduces the risk of cancer recurrence by 25% in high-risk breast cancer patients with early hormone receptor positive (HR +) receptor 2 negative for human epidermal growth factor (HER2-). ), based on the results of an ESMO 2020 study.
“This is the first time in more than 20 years that we have seen an advance in adjuvant treatment for this form of breast cancer,” said lead author Professor Stephen Johnston, Royal Marsden Hospital NHS Foundation Trust, London, UK. United. He explained that hormone receptor-positive breast cancer is the most common form of breast cancer, affecting 70% of patients, and most are diagnosed with an early disease.
“Many of these patients can be cured with currently available treatments: surgery, radiation therapy, chemotherapy and hormonal treatment. But about 20% have high-risk disease and will develop a recurrence, either locally in the breast or elsewhere. of the body during the first ten years. years of treatment, “he explained.
“These high-risk early breast cancer patients show a degree of resistance to hormone therapy, relapsing early despite all that we currently give them,” Johnston said.
“CDK4 / 6 inhibitors, such as abemaciclib, have transformed the way we treat metastatic breast cancer in recent years, bypassing primary endocrine resistance and improving survival. So it was an obvious step to see whether to add abemaciclib to treatment. hormonal therapy in high-risk early breast cancer patients may reduce the risk of the cancer coming back. “
The international phase 3 monarchE study included 5,637 HR + HER2- early breast cancer patients with clinical and / or pathological risk factors that put them at high risk of relapse. After completing their primary treatment, they were openly randomized to abemaciclib (150 mg twice daily for two years) plus endocrine therapy or endocrine therapy alone.
We found a 25% reduction in cancer recurrence with the first two years when abemaciclib was added to hormone therapy compared to hormone therapy alone. “
Stephen Johnston, lead study author and professor, Royal Marsden Hospital NHS Foundation Trust, London
During this time, 11.3% of patients in the control group had a relapse of their cancer compared with 7.8% of those in the abemaciclib group, an absolute difference of 3.5% that translates into a 25.3% risk reduction. Most of the reductions occurred at distant metastatic sites, especially the liver and bone.
“This is the first study to show that the addition of a CDK4 / 6 inhibitor to endocrine therapy significantly improves invasive disease-free survival in the adjuvant setting,” said Giuseppe Curigliano, associate professor of medical oncology at the University of Milan. , Italy, and chair of the ESMO Guidelines Committee.
“This is a very important trial and the findings will change practice. Once approved for HR + HER2- high-risk early breast cancer, the new standard of care for these patients will be adding two years of abemaciclib to endocrine therapy.” , He suggested.
Curigliano suggested that it would have been interesting to have included the genetic signature in the evaluation of high-risk patients, in addition to the number of positive lymph nodes, tumor size, histological grade, and Ki-67 (a proliferation marker).
Johnston said that tissue and plasma samples had been collected from all study participants for translational research that will include observation of genomic signatures and response to abemaciclib.
“The safety data is important, in particular the number of patients treated with abemaciclib who had to stop treatment or required dose reductions due to side effects,” Curigliano said.
A total of 463 (16.6%) of the patients discontinued abemaciclib use due to adverse events, most commonly diarrhea; 306 of them continued with endocrine therapy. The protocol allowed for dose reduction from 150 to 100 mg twice daily if necessary.
He noted: “Treatment adherence will be an important issue to consider in the real-life patient population when this treatment is approved and used in clinical practice.”
Curigliano added: “For the future it will be important to understand whether we can do without chemotherapy in this group of patients treated with a CDK4 / 6 inhibitor. This should be investigated in a randomized clinical trial.”
Source:
European Society for Medical Oncology
Magazine reference:
Johnston, SRD, et al. (2020) Abemaciclib combined with endocrine therapy for the adjuvant treatment of HR +, HER2−, early node-positive breast cancer, high risk, and early breast cancer (monarchE). Journal of Clinical Oncology. doi.org/10.1200/JCO.20.02514.
