Prof Sunil Badve speaks to ecancer about tumour infiltrating lymphocytes (TILs) and pathologic complete response (pCR) in stage II/III HER2+ breast cancer treated with taxane, trastuzumab, and pertuzumab (THP): secondary results from the ECOG-ACRIN EA1181/CompassHER2 pCR trial.

In this analysis, researchers evaluated whether stromal tumour-infiltrating lymphocytes (sTILs) predict pathologic complete response (pCR) in stage II/III HER2-positive breast cancer treated with preoperative trastuzumab, pertuzumab, and taxane chemotherapy (THP).

Prof Badve says that among 1,328 evaluable patients, higher sTIL levels, whether analysed continuously or by clinically relevant cutoffs, were significantly associated with higher pCR rates, particularly in HER2+/ER+ disease.

Overall pCR was 44.5%, but increased markedly as sTIL density rose, reinforcing the role of tumour immunity and highlighting sTILs as a promising tool to identify patients most likely to benefit from de-escalated or optimised HER2-targeted therapy.