Losmapimod (GW856553, GW856553X, GSK-AHAB) is a potent and selective inhibitor of p38 MAPK with pKi values of 8.1 and 7.6 for p38α and p38β, respectively [1].

p38 mitogen-activated protein kinase (p38 MAPK) is an intracellular signaling kinase and plays an important role in regulating transcription and translation of the inflammatory response in macrophages and endothelial cells [2].

Losmapimod is an orally active p38 MAPK inhibitor. In the spontaneously hypertensive stroke-prone rats (SHR-SPs) with a salt-fat diet, GSK-AHAB significantly improved survival and renal function in a dose-dependent way and induced vascular relaxation. Also, GSK-AHAB attenuated hypertension, cardiac remodeling, dyslipidemia, plasma renin activity (PRA), interleukin-1
(IL-1
) and aldosterone [1]. In patients with hypercholesterolemia, losmapimod improved acetylcholine, sodium nitroprusside and NG-monomethyl-L-arginine (L-NMMA) responses by 25%, 20% and 10%, respectively. Also, losmapimod reduced C-reactive protein (a systemic inflammatory marker) by 57%. These results suggested that losmapimod improved NO-mediated vasodilatation and inhibited inflammation [2]. In patients with chronic obstructive pulmonary disease (COPD), losmapimod (7.5 mg twice daily) reduced plasma fibrinogen by 11% and was well tolerated [3].

References:
[1].? Willette RN, Eybye ME, Olzinski AR, et al. Differential effects of p38 mitogen-activated protein kinase and cyclooxygenase 2 inhibitors in a model of cardiovascular disease. J Pharmacol Exp Ther, 2009, 330(3): 964-970.
[2].? Cheriyan J, Webb AJ, Sarov-Blat L, et al. Inhibition of p38 mitogen-activated protein kinase improves nitric oxide-mediated vasodilatation and reduces inflammation in hypercholesterolemia. Circulation., 2011, 123(5): 515-523.
[3].? Lomas DA, Lipson DA, Miller BE, et al. An oral inhibitor of p38 MAP kinase reduces plasma fibrinogen in patients with chronic obstructive pulmonary disease. J Clin Pharmacol, 2012, 52(3): 416-424.