Elizabeth A. Mittendorf, MD, PhD, Impact Grantee Dana-Farber Cancer Institute Area of Research: Breast Cancer Immunotherapy has revolutionized the management of patients diagnosed with triple negative breast cancer (TNBC), with anti-PD-1 checkpoint blockade now standard in the first-line setting for metastatic, PD-L1-positive TNBC, and in the neoadjuvant (pre-surgical) setting in combination with chemotherapy for early-stage TNBC regardless of PD-L1 status. In the latter setting, some patients might not need immunotherapy to respond though, and determining who could spare them from possible side effects. This is the question that Dr. Elizabeth Mittendorf is investigating in the Neo-TRIBUTE (Translational Resource for Immuno-Biology to Understand Therapeutic Efficacy) clinical trial. By utilizing multiplex tissue imaging and biospecimens obtained from blood, tissue, and stool before and throughout treatment, Dr. Mittendorf’s team hopes to gain a better understanding of how immunotherapy influences tumor-infiltrating and circulating immune cells as well as how spatial organization of immune cells is associated with response to therapy. Ultimately, they hope to identify composite biomarkers that reflect the tumor, the microenvironment, and patient’s systemic immune status that predicts who is likely to benefit from adding immunotherapy to chemotherapy as well as those most likely to experience toxicity, in order to improve care in the clinic.