CCG258747

CCG258747 is an indazole analog of paroxetine with highly potent GRK2 inhibitory activity (18 nM in cell-free assay). Potent GRK2 inhibition was also confirmed in a kinase selectivity and profiling assay panel, which also revealed strong selectivity against GRK1, GRK3, GRK4, GRK7, protein kinase D (PRKD2), and ROCK1, and also against 104 other protein kinases (approx. 20% of the human kinome). Selectivity was also confirmed against GRK5 and PKA. CCG258747 was confirmed to penetrate cell membranes and demonstrated robust efficiency in inhibiting MOR phosphorylation and internalisation at 20 uM (HEK293 and U2OS cells stably expressing SpH-MOR). However, GPCR internalisation blocking efficiency was not tested in a more physiological setting, such as cultured neurons, which may express a significantly lower MOR density. Furthermore, a crystal structure of GRK2-CCG258747 is also available (PDB: 6U7C). CCG258747 needs further exploration before in vivo use for interrogating GRK2 physiological and pathological roles. Indeed, CCG258747 showed better metabolic stability than paroxetine, and plasma levels exceeded the GRK2 IC50 for at least 7 h. However, considering that CCG258747 efficiency against MOR internalisation was confirmed in cells at 20 uM (concentration higher than Cmax = 1.530 uM) and is dependent on diffusion across plasma membrane, a single intraperitoneal dose of 10 mg/kg might not be sufficient to exhibit the desired pharmacological effects. Therefore, further experimentation is warranted to confirm the in vivo efficiency at various doses and to investigate the potential toxicity of CCG258747 in model organisms.