spaXio is an innovative European Marie Skłodowska-Curie Actions (MSCA) doctoral training network focused on understanding how cancer spreads to distant organs — a process known as metastasis. Metastasis is a major cause of death and, once established, metastatic disease can be controlled by treatment, but not cured. Understanding how tumor cells develop in a new environment, how they grow and interact with it, will not only help explain why cancer becomes metastatic, but also open up new therapeutic perspectives for treating metastases.  spaXio combines cutting-edge methods like spatial multi-omics, 3D tumoroid models, and AI-powered data analysis to uncover how metastatic niches form and how they might be targeted therapeutically. 13 doctoral candidates will receive interdisciplinary hands-on training in academic and industry settings, preparing them to become leaders in cancer research and pioneers in the rapidly growing field of spatial biology.