Monovalent Nondegrading Molecular Glues: An Updated Overview of Emerging Mechanisms and Therapeutic Development

Chemically induced proximity (CIP) has revolutionized small-molecule pharmacology by moving beyond traditional occupancy-based inhibition and activation. Within this paradigm, monovalent nondegrading molecular glues (ndMGs) represent a structurally compact and mechanistically distinct class of linkerless compounds. These agents stabilize or induce selective biomolecular interactions, altering the functional state or cellular localization of macromolecular complexes without causing component degradation. Once considered rare phenomena unique to specific natural products, ndMGs are now being actively engineered across diverse therapeutic landscapes, with multiple candidates advancing into clinical trials and achieving regulatory validation. We systematically highlight their evolving capabilities to modulate oncogenic networks, intervene with immune activity, rectify metabolic signaling, control neurodegenerative trafficking and stress networks, and disrupt critical pathogen assemblies, while broadening the druggable landscape into non-canonical mechanisms. In each section, we analyze the therapeutic value of the targets, the molecular mechanisms of action, the latest progress, and the unique challenges faced by these strategies. In summary, the ndMG modality represents a highly versatile strategy to unlock the undruggable proteome.