Protocol for establishing a chemoresistant orthotopic triple-negative breast cancer patient-derived xenograft model for preclinical drug testing

Here, we present a protocol for establishing patient-derived xenograft (PDX) mouse models of chemoresistant triple-negative breast cancer (TNBC). We describe steps for tumor collection, surgical implantation, and serial expansion. We then detail procedures for histopathological validation and in vivo therapeutic assessment to confirm the maintenance of chemoresistance across passages. These models provide a clinically relevant platform to investigate mechanisms of treatment resistance, evaluate novel therapeutic strategies in preclinical settings, and predict therapeutic responses in refractory TNBC. • Establishment of chemoresistant TNBC patient-derived xenograft (PDX) models • Orthotopic implantation into the mammary fat pad of immunodeficient NSG mice • Serial passaging to preserve tumor identity and treatment resistance • Preclinical drug evaluation maintaining tumor biology and resistance phenotype Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics. Here, we present a protocol for establishing patient-derived xenograft (PDX) mouse models of chemoresistant triple-negative breast cancer (TNBC). We describe steps for tumor collection, surgical implantation, and serial expansion. We then detail procedures for histopathological validation and in vivo therapeutic assessment to confirm the maintenance of chemoresistance across passages. These models provide a clinically relevant platform for investigating mechanisms of treatment resistance, preclinical testing of novel therapeutic strategies, and predicting therapeutic responses in refractory TNBC.