Prexasertib Mesylate Hydrate (LY2606368 Mesylate Hydrate) is a potent, selective, ATP competitive CHK1 and CHK2 inhibitor, with a Ki of 0.9 nM for CHK1 and IC50s of <1 nM, 8 nM for CHK1 and CHK2, respectively. Prexasertib Mesylate Hydrate inhibits HT-29 CHK1 autophosphorylation (S296) and HT-29 CHK2 autophosphorylation (S516). Prexasertib Mesylate Hydrate shows potent anti-tumor activity, significantly abrogates the G2/M checkpoint in p53 deficient HeLa cells with an EC50 of 9 nM. Chk1|0.9 nM (Ki)|Chk1|<1 nM (IC50)|Chk2|8 nM (IC50) Prexasertib Mesylate Hydrate (LY2606368 Mesylate Hydrate) is an ATP competitive CHK1 inhibitor, with a Ki of 0.9 nM and an IC50 of <1 nM.Prexasertib (LY2606368) shows high anti-tumor activity against U-2 OS, Calu-6 and HeLa cells (IC50, 3, 3, 37 nM, respectively), causes DNA damage during S-phase requiring CDC25A and CDK2 at 4 μM.Prexasertib (0-20 nM) synergizes with olaparib (0-20 μM) to decrease cell viability in HGSOC cells.