At the ongoing AAAAI meeting in San Antonio, researchers from Escient Pharmaceuticals Inc. presented preclinical data for the Mas-related G-protein coupled receptor X2 (MRGPRX2) antagonist EP-262, being evaluated as a novel therapeutic approach for mast cell-mediated diseases. In vitro, EP-262 acted as a potent and highly selective antagonist of MRGPRX2, which inhibited MRGPRX2 activation induced by a wide variety of agonists.