Research progress and future perspectives in proteolysis-targeting chimeras.

Proteolysis-targeting chimeras (PROTACs) have emerged as a transformative modality within the targeted protein degradation (TPD) landscape, inducing spatial proximity between E3 ubiquitin ligases and proteins of interest (POIs) to hijack the ubiquitin-proteasome system (UPS). Unlike traditional occupancy-driven inhibitors, this catalytic, event-driven mechanism enables the targeting of historically "undruggable" proteomes and circumvents acquired resistance. However, the field faces formidable challenges, including suboptimal pharmacokinetic profiles, the stoichiometric "hook effect," and a disproportionate reliance on a limited pool of E3 ligases (notably cereblon (CRBN) and von Hippel-Lindau (VHL)). This review critically examines PROTAC core principles and provides a nuanced functional categorization across oncology, immune modulation, neurodegenerative diseases, and basic research. We further evaluate three pivotal technical strategies-degrader architecture innovations, conditional activation modalities, and advanced delivery platforms-while systematically appraising current clinical progress. Finally, we discuss key limitations and future translational directions, aiming to provide a realistic roadmap for the next-generation of TPD therapeutics.