Identification of triazolopyridazinones as potent p38α inhibitors

Structure–activity relationship (SAR) investigations of a novel class of triazolopyridazinone p38α mitogen activated protein kinase (MAPK) inhibitors are disclosed. From these studies, increased in vitro potency was observed for 2,6-disubstituted phenyl moieties and N-ethyl triazolopyridazinone cores due to key contacts with Leu108, Ala157 and Val38. Further investigation led to the identification of three compounds, 3g, 3j and 3m that are highly potent inhibitors of LPS-induced MAPKAP kinase 2 (MK2) phosphorylation in 50% human whole blood (hWB), and possess desirable in vivo pharmacokinetic and kinase selectivity profiles.