BAY-1125976 is an orally bioavailable inhibitor of the serine/threonine protein kinase AKT (protein kinase B) isoforms 1 and 2 (AKT1/2) with potential antineoplastic activity. AKT1/2 inhibitor BAY1125976 selectively binds to and inhibits the phosphorylation and activity of AKT1/2 in a non-ATP competitive manner, which may result in the inhibition of the phosphatidylinositol 3 (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway. This may lead to both the reduction of cell proliferation and the induction of cell apoptosis in AKT-overexpressing tumor cells. The AKT signaling pathway is often deregulated in cancer and is associated with tumor cell proliferation, survival, and migration. BAY 1125976 is equally potent against Akt1 and Akt2 isoforms and up to 86 fold less potent against Akt3 It inhibits the Akt1 and Akt2 by binding into an allosteric binding pocket formed by kinase and PH domain. It inhibits cell proliferation in a broad panel of human cancer cell lines, particularly in breast and prostate cancer cell lines expressing estrogen or androgen receptors. It effectively blocks Akt signaling by inhibiting the phosphorylation of Akt and the downstream effectors, including eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1), glycogen synthase kinase 3 beta (GSK3s), proline-rich Akt substrate 40 kDa (PRAS40), S6 ribosomal protein (S6RP), and 70 kDa ribosomal protein S6 kinase 1 (70S6K). BAY 1125976 exhibits strong in vivo efficacy in both cell line and patient-derived xenograft models such as the KPL4 breast cancer model (PIK3CAH1074R mutant), the MCF7 and HBCx-2 breast cancer models, and the AktE17K mutant driven prostate cancer (LAPC-4) and anal cancer (AXF 984) models.