B7-H3 molecular imaging for the era of pan-cancer targeted therapy.

B7-H3 (CD276) is broadly overexpressed across solid tumors and plays active roles in immune evasion, tumor angiogenesis, and metabolic reprogramming. As B7-H3-directed antibody-drug conjugates chimeric antigen receptor T-cell therapies, and radioimmunotherapy agents advance through clinical trials, non-invasive whole-body imaging of B7-H3 expression has become a pressing clinical need. Tissue biopsy with IHC cannot capture systemic target heterogeneity, and the recent IDeate-PanTumor01 trial found no correlation between baseline B7-H3 H-score and response to ifinatamab deruxtecan-illustrating the gap that molecular imaging must fill. This mini review surveys B7-H3-targeted imaging agents by scaffold class-antibodies, affibodies, nanobodies, and bicyclic peptides-and examines radioimmunotherapy platforms that couple PET-based dosimetry with targeted radionuclide delivery.