CDK4/6 inhibitors have shown efficacy in breast cancer, and are gaining attention as a promising treatment option. Sibylle Loibl, MD, PhD, from the University of Frankfurt, Frankfurt, Germany discusses the attention that these agents are receiving, talking us through clinical trials such as the MONARCH 3 study (NCT02246621) and the PALOMA-2 study (NCT01740427). Prof. Liobl also discusses two clinical trials which aim to examine the efficacy of CDK4/6 inhibitors in HER2-negative breast cancer, MONARCH 2 (NCT02107703) and PALOMA-3 (NCT01942135), and explains the need to discover markers to identify which patients would respond best to this these treatments. This interview was recorded at the 2017 European Society for Medical Oncology (ESMO) conference held in Madrid, Spain.