Marleen Kok, MD, PhD, Netherlands Cancer Institute, Amsterdam, Netherlands, gives an overview of the role of the tumor microenvironment in triple-negative breast cancer (TNBC), highlighting the use of novel tools for analysis. In particular, Dr Kok discusses multiplex technologies and single-cell RNA sequencing. This interview took place at the virtual European Society for Medical Oncology (ESMO) Breast Cancer Congress 2021.