Background
HR-positive/HER2-negative advanced breast cancer, non-visceral disease
PROLIFERATIVE
Endocrine therapy has been the established treatment for patients with hormone receptor (HR)-positive, human epidermal growth factor receptor (HER2)-negative advanced breast cancer for many years. More recently, addition of cyclin-dependent kinase (CDK) 4/6 inhibitors to endocrine therapy has been shown to improve survival outcomes and is now considered standard of care in this setting [One option, based on findings of the Phase III BOLERO-2 trial, is exemestane plus everolimus, a mammalian target of rapamycin (mTOR) inhibitor [Preclinical data suggest that the efficacy of mTOR inhibitors may be limited by compensatory signalling via the insulin-like growth factor (IGF) type 1 receptor (IGF-1R), which results in activation of AKT [Xentuzumab is a humanised monoclonal antibody that binds to the IGF-1 and IGF-2 ligands and neutralises their proliferative activity [Here, we report results of a randomised Phase II trial (NCT03659136) that evaluated the addition of xentuzumab to everolimus and exemestane in patients with HR-positive/HER2-negative advanced breast cancer with non-visceral disease who had received prior endocrine therapy with or without CDK4/6 inhibitors.