PP149 CD24hiCD27+Bregs within mLN orchestrate the stemness and multi-drug resistance of breast cancer cells via direct contact-interaction

Axillary lymph node (LN) is the primary and dominant metastatic organ in breast cancer (BC), and lymph node metastasis (mLN) not only associated with poor prognosis, but also the axillary lymph node dissection (ALND) greatly affect the living quality of patients. In addition, recent researches strongly suggested the importance of mLN to the immune checkpoints inhibition efficiency. More than 10% of BC patients receiving neoadjuvant therapy (NAT) get breast pCR but still have residual tumor cells in mLN, indicating a different drug resistance mechanism between the primary lesion and mLN.