Expression of MT4-MMP, EGFR and Rb in triple negative breast cancers strongly sensitizes tumors to Erlotinib and Palbociclib combination therapy

Triple negative breast cancer (TNBC) comprises heterogeneous tumors displaying an aggressive pattern of progression and metastasis. The standard systemic treatment relies entirely on chemotherapy. While epidermal growth factor receptor (EGFR) is frequently over-expressed in TNBC, targeted therapies against EGFR did not show clinical benefit. Recently, we demonstrated that EGFR interacts with MT4-MMP, the membrane-type 4 matrix metalloproteinase in TNBC. Also, based on an immunohistochemistry (IHC) analysis we reported that EGFR and MT4-MMP are co-expressed in 79 % of human TNBC samples. Here, we identified MT4-MMP/EGFR axis as an important driver of cancer cell proliferation through CDK4 activation and retinoblastoma protein (Rb) inactivation. Finally, we investigated the significance of targeting EGFR and CDK4 in TNBC expressing MT4-MMP and EGFR.