NCT05917821 is an observational, discovery-stage immunotherapy study aiming to identify glioblastoma (GB)-specific antigens and select/develop therapeutic monoclonal antibodies (mAbs). Drug/intervention: therapeutic mAbs (biologic antibodies). Intended mechanisms: bind GB-specific cell-surface antigens to (a) directly block oncogenic/ survival receptor signaling and (b) recruit immune effector functions such as antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). Methods include tissue microarrays to map mAb specificity and target distribution, and selection of GB-specific functional mAbs. Target cells/pathways: glioblastoma tumor cells expressing GB-restricted antigens, the exact pathways depend on identified antigens, with focus on tumor-associated surface targets to maximize tumor selectivity and minimize off-tumor binding. No therapeutics are administered to participants in this phase. Status: not yet recruiting.