Copanlisib (BAY 80-6946) is a phosphoinositide 3-kinase (PI3K) inhibitor with potential antineoplastic activity. Copanlisib inhibits the activation of the PI3K signaling pathway, which may result in inhibition of tumor cell growth and survival in susceptible tumor cell populations. Activation of the PI3K signaling pathway is frequently associated with tumorigenesis and dysregulated PI3K signaling may contribute to tumor resistance to a variety of antineoplastic agents.

In both KPL4 cells and LPA-stimulated PC3 cells, BAY 80-6946 reduces pAKT levels. In a subset of human cancer cell lines with PIK3CA mutations and/or overexpression of HER2, BAY 80-6946 shows antiproliferative activity and induces apoptosis. [1] The combination of HER2-targeted therapies and BAY 80-6946 inhibits growth more effectively than either therapy used alone, and can restore sensitivity to trastuzumab and lapatinib in cells. [2]

In rat KPL4 or HCT116 tumor xenograft model, BAY 80-6946 (6 mg/kg, i.v.) induces 100% complete tumor regression. In nude mice with Lu7860 erlotinib-resistant, patient-derived NSCLC and MAXF1398 patient-derived luminal breast tumor models, BAY 80-6946 (14 mg/kg, i.v.) also causes tumor growth inhibition. [1]

Biochemical lipid kinase assays: The effect of BAY 80-6946 on PI3Kα, PI3Kβ, and PI3Kγ activity is measured by the inhibition of 33P incorporation into phosphatidylinositol (PI) in 384-well MaxiSorp? plates coated with 2 μg/well of PI and phosphatidylserine (PS) (1:1 molar ratio). In each PI3K isoform assay, 9 μL of reaction buffer (50 mM MOPSO, pH 7.0, 100 mM NaCl, 4 mM MgCl2, 0.1% BSA) containing 7.5 ng of His-tagged N-terminal truncated p110α or p110β protein, or 25 ng of purified human p110γ protein, is used. The reaction is started by adding 5 μL of a 40-μM ATP solution containing 20 μCi/mL [33>/sup>P]-ATP. After 2 hours incubation at room temperature, the reaction is terminated by addition of 5 μL of a 25-mM EDTA solution. The plates are washed and Ultima Gold? scintillation cocktail (25 μL) is then added. The radioactivity incorporated into the immobilized PI substrate is determined with a BetaPlate Liquid Scintillation Counter.

Cell proliferation over a 72-hour period is determined using the CellTiter-Glo? luminescent cell viability kit. Briefly, cells are plated in separate microtiter plates. Following an overnight incubation at 37oC, luminescence values in the t=0 hour plates are determined. Test compounds diluted in growth medium are added to the t=72 hour plates, and the cells are then incubated for 72 hours at 37oC. Luminescence values are determined with a Wallac 1420 Victor2? 1420 multilabel HTS counter after a 10-minute reaction with CellTiter-Glo? solution. The percentage inhibition of cell growth is calculated by subtracting the luminescence values in the t=0 hour plates from the corresponding values in the t=72 hour plates. Differences in values between drug-treated cells and controls are used to determine the percentage inhibition of cell growth.(Only for Reference)