Beyond the traditional dish: Advanced 3D ex vivo culture platforms for tumor modelling

The tumor microenvironment (TME) and its complex, dynamic interactions play a pivotal role in cancer development, progression and therapy response. However, faithful recapitulation of the diverse cellular and structural components of the TME in vitro remains a major challenge in cancer research. Traditional 2D cancer cell cultures fail to preserve TME interactions and tissue organization that critically impacts tumor behavior, while advanced 3D systems, including organoids, 3D-bioprinted structures and microfluidic platforms capture only selected aspects of TME complexity and host physiology. Recent advances in the culture of primary tumor specimens with minimal disruption to tissue architecture has led to a rapidly evolving set of model systems that benefit TME research. These ex vivo cultures (EVCs), as we collectively refer to them here, are established from fresh primary tumor tissue and preserve the native tumor architecture, extracellular matrix composition, immune and stromal compartments and their multilayered crosstalk within a physiologically relevant context. This review outlines the historical evolution of 2D and 3D model systems in oncology, followed by a comprehensive overview of current EVC methodologies. Furthermore, we address their applications in fundamental cancer research, personalized medicine and drug discovery, while highlighting their advances and challenges for the future.