TSHR antagonist S37a is a highly selective thyrotropin receptor (TSHR) antagonist, with potential for the treatment of Graves’ orbitopathy[1].
TSHR antagonist S37a exhibits inhibition activity for TSHR, with IC50s of 40 µM and approximately 20 µM for mTSHR and hTSHR, respectively, in HEK293 cells[1].TSHR antagonist S37a not only inhibits the TSHR activation by thyrotropin itself but also activation by monoclonal TSAb M22 (human), KSAb1 (murine), and the allosteric small-molecule agonist C2[1].
TSHR antagonist S37a also inhibits cyclic adenosine monophosphate formation by oligoclonal TSAb, which are highly enriched in GO patients’ sera[1].TSHR antagonist S37a (10 mg/kg ;i.g.) displays no toxicity and a remarkable 53% oral bioavailability in mice[1].
[1]. Marcinkowski P, et al. A New Highly Thyrotropin Receptor-Selective Small-Molecule Antagonist with Potential for the Treatment of Graves’ Orbitopathy. Thyroid. 2019 Jan;29(1):111-123.