Gaia Griguolo, MD, Instituto Oncologico Veneto I.R.C.C.S, Padova, Italy, discusses the results from a study investigating spatial interactions between immune cells in patients with HER2-positive breast cancer (BC) and triple-negative breast cancer (TNBC) with brain metastases. Using multiplex immunofluorescence (mIF), an interaction between PD-L1-positive CD163-positive M2 macrophages and PD-1-positive CD3-positive T-cells was associated with a worse prognosis in patients with HER2-positive BC. This information might help design therapeutic strategies combining anti-HER2 targeted agents and anti-PD-1 or anti-PD-L1 immunotherapeutic agents for this patient population. Conversely, a variety of immune interactions associated with a positive prognostic impact were observed in TNBC. This interview took place at the European Society for Medical Oncology (ESMO) 2021 congress.