Targeting lysosomal dysfunction with small-molecule TRPML1 ligands: Therapeutic opportunities in lysosomal storage disorders, neurodegeneration and beyond.

TRPML1, a lysosomal Ca2+ channel, has emerged as a clinically relevant target due to its genetic and mechanistic links to lysosomal storage disorders and neurodegenerative diseases, including Gaucher disease, Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. This evidence has prompted TRPML1 drug discovery efforts across academia and industry, with several small-molecule agonists advancing toward clinical development. In this review, we provide a comprehensive overview of the therapeutic potential of TRPML1 as a molecular target from a medicinal chemistry perspective. We summarize the structural basis of channel activation and inhibition, highlighting insights from recent cryo-EM studies that define the principal ligand-binding sites and mechanisms of allosteric modulation. We systematically survey the chemical space of TRPML1 ligands reported to date, including diverse agonist and antagonist chemotypes, and extend this analysis to encompass undisclosed or recently disclosed compounds emerging from industry pipelines. Furthermore, we discuss key determinants of ligand design and developability, including the challenges associated with targeting a deeply embedded, lipophilic binding pocket within the membrane. Overall, the available evidence positions TRPML1 as a promising target for small-molecule drug discovery and provides a framework for the rational design of next-generation lysosome-directed therapeutics.