Breast Cancer Patient-derived Organoids as case study for the investigation of patient's specific tumour evolution. Homo sapiens

Breast cancer (BC) is the most diagnosed type of tumour and the principal cause of death among women worldwide. In recent years, three-dimensional (3D) cell cultures have been widely used as a preclinical model of numerous diseases, including cancer, to bridge the gap between two-dimensional (2D) cell cultures and animal models. More recently, the tumour patient-derived organoid (PDO) approach, in which the cellular complexity and the internal genetic heterogeneity of original cancerous tissue are preserved, has emerged as a very promising tool in translational cancer research and personalized cancer medicine. Organoid cultures consist of clusters of organ-specific cells (stem or progenitors) directly derived from fragments of the original tumour. In the case of BC, PDOs may be much more useful to study tumour evolution, aiming to resolve the molecular and cellular complexity of the tumour and directing towards more effective therapies. In this study, we report the case of a 69-years-old BC patient from whom two PDO cultures were successfully established from specimens collected before (O-PRE) and after (O-POST) neoadjuvant chemotherapy (NACT). Thanks to an extensive characterization of both PDO cultures by flow cytometry, immunofluorescence immunohistochemistry and bulk RNA-seq analysis combined with single-cell sequencing (scRNA-seq) analysis to have a resolution at single-cell level, we have achieved a model able to resume in vitro patient's tumour evolution following NACT, obtaining specific cell-type gene expression changes and biological and molecular portraits focusing on the expression profile of some biomarkers associated with tumour proliferation and metastasis.