Breast cancer is the most diagnosed cancer among women over the world, ranking it in the second place globally for cancer-related mortality. Out of the four subtypes of breast cancer known, triple-negative breast cancer (TNBC) has the most aggressive phenotype. It often tends to relapse post standard chemotherapy and radiotherapy in over 50% of the patients. In this study, we first developed an innovative platform of an antibody-drug conjugate (ADC) carrying two payloads (DualADC), a cytotoxic topoisomerase inhibitor and an immunoregulating toll-like receptor (TLR7/8) agonist. Topoisomerase inhibitors are a group of anti-cancer agents that arrest cancer cell growth by causing accumulation of DNA strand breaks leading to severe cell death. TLR 7/8 agonists play a pivotal role in recruiting and activating immune cells within the immunologically "cold" tumor microenvironment. Furthermore, we developed a monoclonal antibody to target EpCAM, a transmembrane protein overexpressed in TNBCs and associated with cancer cell adhesion, proliferation, migration, and epithelial-to-mesenchymal transition. Then we developed the scalable biomanufacturing of anti-EpCAM DualADC and characterized its TNBC targeting, drug delivery and cytotoxicity. This new all-in-one molecule showed great potential in TNBC treatment by reducing tumor burden, inhibiting metastasis, and blocking the heterogenous patient-derived xenograft (PDX) growth in mouse models. The mechanism of action studies indicated synergistic anti-cancer mechanisms such as DNA damage, immune upregulation and apoptosis. The translational evaluations will be performed to facilitate pre-clinical and clinical trials in future.
