PD 176252: The first high affinity non-peptide gastrin-releasing peptide (BB2) receptor antagonist

Abstract In this paper we describe the development of a novel series of non-peptide, “balanced” neuromedin-B preferring (BB 1 )/gastrin-releasing peptide preferring (BB 2 ) receptor ligands as exemplified by PD 176252. PD 176252, which exhibits nanomolar affinity for both the BB 1 (K i =0.15nM) and BB 2 (K i =1.0nM) receptors, has been demonstrated to be a competitive antagonist at these bombesin receptor subtypes.