RI-962 (RI 962) is a potent and selective RIPK1 inhibitor with IC50 of 5.9 nM in ADP-Glo assays.
RI-962 shows little to no activity against a panel of 408 human kinases (IC50>10 μM) except MLK3 (IC50=3.75 μM, 107-fold less potent against MLK3 than against RIPK1).
RI-962 occupies both the ATP-binding pocket and the allosteric site simultaneously, indicating a type II kinase inhibitor.
RI-962 exerted a dose-dependent protective effect against necroptotic death, with EC50 values of 10.0, 4.2, 11.4, and 17.8 nM for HT29, L929, J774A.1, and U937 cells, respectively.
RI-962 inhibited TSZ-induced necroptosis and improved cell survival in a concentration-dependent manner, which is more potent than positive control GSK3145095.
RI-962 markedly inhibited the phosphorylation of RIPK1 and its downstream signaling proteins RIPK3 and MLKL in a dose-dependent manner.
RI-962 (40 mg/kg, i.v.) remarkably reduced the TNFα-induced systemic inflammatory response syndrome (SIRS), and the concentrations of proinflammatory cytokines (IL-1β and IL-6) in mice.
RI-962 reduced inflammation in acute DSS-induced colitis, reduced the levels of pRIPK1, pRIPK3, and pMLKL proteins in the colon during DSS challenge, but did not impact the expression of RIPK1, RIPK3, and MLKL proteins.