Discovery of a Novel Small Molecule Modulator of C-X-C Chemokine Receptor Type 7 as a Treatment for Cardiac Fibrosis.

C-X-C chemokine receptor type 7 (CXCR7) is involved in cardiac and immune pathophysiology. We report the discovery of a novel 1,4-diazepine CXCR7 modulator, demonstrating for the first time the role of pharmacological CXCR7 intervention in cardiac repair. Structure activityrelationship (SAR) studies demonstrated that a net reduction in lipophilicity (log D) and an incorporation of saturated ring systems yielded compounds with good CXCR7 potencies and improvements in oxidative metabolic stability in human-liver microsomes (HLM). Tethering an ethylene amide further improved the selectivity profile (e.g., for compound 18, CXCR7 K-i = 13 nM, adrenergic alpha la K-b > 10 000 nM, and adrenergic beta 2 K-b > 10 000 nM). The subcutaneous administration of 18 in mice led to a statistically significant increase in circulating concentrations of plasma stromal-cell-derived factor la (SDF-1 alpha) of approximately 2-fold. Chronic dosing of compound 18 in a mouse model of isoproterenol-induced cardiac injury further resulted in a statistically significant reduction of cardiac fibrosis.