In vitro activity: BAY-1895344 is a potent, highly selective and orally available ATR (ataxia telangiectasia and Rad3-related) inhibitor with an IC50 of 7 nM. In vitro, BAY 1895344 potently inhibits proliferation of a broad spectrum of human tumor cell lines (median IC50 = 78 nM). In cellular mechanistic assays BAY 1895344 potently inhibited hydroxyurea-induced H2AX phosphorylation (IC50 = 36 nM). Moreover, BAY 1895344 revealed significantly improved aqueous solubility, bioavailability across species and no activity in the hERG patch-clamp assay. BAY 1895344 also demonstrated very promising efficacy in monotherapy in DNA damage deficient tumor models as well as combination treatment with DNA damage inducing therapies. The start of clinical investigation of BAY 1895344 is planned for early 2017.

Kinase Assay: BAY 1895344 is shown to be a very potent and highly selective ATR inhibitor (IC50 = 7 nM), which potently inhibits proliferation of a broad spectrum of human tumor cell lines (median IC50 = 78 nM). In cellular mechanistic assays BAY 1895344 potently inhibits hydroxyurea-induced H2AX phosphorylation (IC50 = 36 nM).

Cell Assay: In cellular mechanistic assays BAY 1895344 potently inhibited hydroxyurea-induced H2AX phosphorylation (IC50 = 36 nM).