Abstract PS5-03: Celtil score and long-term survival outcome in early stage HER2-positive (HER2+) breast cancer treated with anti-HER2-based chemotherapy: A correlative analysis of neoALTTO trial

Background: Biomarkers to help escalate or de-escalate systemic therapies are urgently needed in early-stage HER2+ breast cancer patients. The combination of high stromal tumor infiltrating lymphocytes (TILs) and low tumor cellularity at 2 weeks of anti-HER2 therapy (CelTIL score) has been associated with high rates of pathologic complete response (pCR) after completion of neoadjuvant therapy. However, the value of CelTIL as a prognostic...