Real-world characteristics, treatment patterns and clinical outcomes among patients with high-risk, early-stage, estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2–) breast cancer – retrospective cohort study

Objectif(s) de la recherche et intérêt pour la santé publique

Finalité de l'étude

Objectifs poursuivis

Domaines médicaux investigués

Bénéfices attendus

Breast cancer is among the leading causes of cancer deaths in women worldwide and the ER+/HER2- immunohistochemical subtype is the most prevalent form. When diagnosed early and treated effectively, it has a low recurrence rate and good prognosis. However, ER+/HER2– breast cancer is a heterogeneous disease and includes a subpopulation that is at high risk of recurrence and has poor long-term outcomes. The European Society for Medical Oncology (ESMO) clinical practice guidelines for diagnosis, treatment and follow-up of early breast cancer emphasize the importance of individual risk-benefit analysis for every patient to guide treatment pathways, indicating that there is variability in standards of care. The treatment landscape has also shifted in recent years, with increasing emphasis on the potential survival benefits of neoadjuvant and adjuvant chemotherapy of the same regimen. There has also been growing recognition of the potential for improvements in the rate of pathological complete response (pCR) through the introduction of novel immunotherapies or targeted therapies such as abemaciclib, in combination with chemotherapy. Results from Merck’s Phase III trial KEYNOTE-756 show that the novel immunotherapy KEYTRUDA® (pembrolizumab) in combination with chemotherapy, significantly improves pCR among high-risk ER+/HER2- breast cancer patients, compared to placebo in combination with chemotherapy in the neoadjuvant and adjuvant setting. Given these recent advances and ongoing research into these novel immunotherapies and their settings for high-risk ER+/HER2- breast cancer, there is a need to better understand real-world patient characteristics, treatment patterns and clinical outcomes to inform understanding of unmet needs of the disease. This study aims to fill the gap in knowledge of the characteristics of high-risk ER+/HER2- early breast cancer patients and their treatment patterns in recent years. It also aims to provide real world evidence of clinical outcomes among high-risk ER+/HER2- early breast cancer patients who have received neoadjuvant chemotherapy and those who have received adjuvant chemotherapy and/or adjuvant abemaciclib.