ML161 is a selective inhibitor of PAR1 with IC50 value of 0.26 μM [1].

Protease-activated receptor-1(PAR-1) is a unique G-protein-coupled receptor belonging to the protease-activated receptor family and its activation leads to downstream signaling events that launch a variety of cellular responses related to tumor progression [1].

ML161 is a potent PAR1 inhibitor and has a different selectivity with the reported ALK inhibitor crizotinib. When tested with human platelets, ML161 treatment inhibited the activation of thrombin-induced platelet in a dose-dependent manner by detecting P-selectin expression [1]. When tested with granule secretion, ML161 exhibited a potent inhibition on P-selectin expression in a dose-dependent manner with EC50 value of 0.3μM and also inhibited SFLLRN-induced thrombus formation [2].

References:
[1].  Dockendorff, C., et al., Discovery of 1,3-Diaminobenzenes as Selective Inhibitors of Platelet Activation at the PAR1 Receptor. ACS Med Chem Lett, 2012. 3(3): p. 232-237.
[2].  VerPlank, L., et al., Chemical Genetic Analysis of Platelet Granule Secretion-Probe 3, in Probe Reports from the NIH Molecular Libraries Program. 2010, National Center for Biotechnology Information (US): Bethesda (MD).