Dexter Lee is a PhD student studying glioblastoma, with a focus on how extrachromosomal DNA (ecDNA) contributes to tumour evolution, spatial organisation, and immune microenvironment remodelling. His PhD work investigates whether ecDNA-positive glioblastoma cells establish distinct cellular neighbourhoods and communication patterns with tumour-infiltrating macrophages and microglia, particularly tumour-associated macrophages. Using single-cell and spatial transcriptomic approaches, including CosMx Spatial Molecular Imaging and 10x Genomics platforms, he aims to characterise malignant cell states, copy-number-driven programmes, and ligand–receptor interactions that may shape immune suppression and therapeutic resistance. He is especially interested in how oncogene amplification and tumour plasticity influence crosstalk between malignant cells and myeloid populations in the glioblastoma microenvironment. Through the Croucher summer course in translational immunology, he hopes to strengthen his understanding of tumour–immune interactions, immune evasion, and immunotherapy principles, and to apply these concepts toward developing more clinically relevant models of ecDNA-associated glioblastoma progression and treatment vulnerability.