3D in-vitro Model: Platform for Evaluating Anticancer-Drugs Targeting Organ-Specific TME in Primary & Metastatic Breast-cancer

Over 90% of cancer-related deaths result from metastatic disease, with a mere 5% survival rate for breast cancer patients with bone metastases. Traditional 2D models often fail to capture tumor complexity, while 3D in vitro models more accurately mimic primary and metastatic tumors, replicating tumor architecture and cancer-stromal interactions. In this study, patient-derived cancer cells (PDCs) from three breast cancer subtypes were cultured in a hanging drop system for primary tumors and a bone-mimetic scaffold for metastasis. Co-culturing with stromal cells (endothelial cells and cancer-associated fibroblasts) replicated the tumor microenvironment (TME). Drug sensitivity tests showed significant cell death in 2D cultures, but 3D models revealed greater resistance in metastatic tumors. Gene analysis confirmed higher survival in these tumors after treatment. Post-treatment, EC segments reduced in cancer-EC co-cultures, but increased when CAFs were included, promoting angiogenesis and drug resistance. The study highlights the need for higher drug doses in bone TME and emphasizes the role of stromal cells in drug resistance. This 3D model proves valuable for anticancer drug testing by effectively simulating primary and metastatic conditions.