Targeting Thyroid-Stimulating Hormone Receptor: A Perspective on Small-Molecule Modulators and Their Therapeutic Potential

TSHR is a member of the glycoprotein hormone receptors, a subfamily of class A G-protein-coupled receptors and plays pivotal roles in various physiological and pathological processes, particularly in thyroid growth and hormone production. The aberrant TSHR function has been implicated in several human diseases including Graves' disease and orbitopathy, nonautoimmune hyperthyroidism, hypothyroidism, cancer, neurological disorders, and osteoporosis. Consequently, TSHR is recognized as an attractive therapeutic target, and targeting TSHR with small-molecule modulators including agonists, antagonists, and inverse agonists offers great potential for drug discovery. In this perspective, we summarize the structures and biological functions of TSHR as well as the recent advances in the development of small-molecule TSHR modulators, highlighting their chemotypes, mode of actions, structure-activity relationships, characterizations, in vitro/in vivo activities, and therapeutic potential. The challenges, new opportunities, and future directions in this area are also discussed.