A Vanderbilt University Medical Center and Stanford University team introduced a spatial single-cell pharmacology (SSP) platform designed to visualize drug–tumor interactions inside human solid tumors at single-cell resolution. Published in Nature Biotechnology, the SSP approach quantifies how therapeutic antibodies distribute, engage targets, and interact with the physical architecture of tumors. The study reported pronounced spatial heterogeneity in delivery and target engagement across head and neck, pancreatic, and other solid tumor types. The results pointed to a consistent limiting factor: dense stromal architecture surrounding tumors, which acts as a physical barrier restricting antibody penetration and downstream activity. The work also analyzed panitumumab-IRDye800CW, an antibody used in Phase I trials and being investigated for fluorescence-guided surgery, demonstrating SSP’s potential to connect therapeutic biology with translational imaging use cases.