The Antigen-Presentation Bottleneck in Pediatric Solid Tumors: Developmental Antigens, MHC-I Suppression, and Therapeutic Restoration of Tumor Immune Recognition

Background

Pediatric solid tumors respond poorly to T-cell-directed immunotherapy despite expressing developmentally restricted, cancer-testis, fusion-derived, and lineage-associated antigens, suggesting that therapeutic failure may reflect defective conversion of intracellular antigen expression into surface peptide-major histocompatibility complex class I (pMHC-I) display. This review examines the antigen-presentation bottleneck as a framework for tumor immune invisibility and therapeutic resistance.