Characterization of the Activity of the PI3K/mTOR Inhibitor XL765 (SAR245409) in Tumor Models with Diverse Genetic Alterations Affecting the PI3K Pathway

Abstract

Activation of the PI3K (phosphoinositide 3-kinase) pathway is a frequent occurrence in human tumors and is thought to promote growth, survival, and resistance to diverse therapies. Here, we report pharmacologic characterization of the pyridopyrimidinone derivative XL765 (SAR245409), a potent and highly selective pan inhibitor of class I PI3Ks (a, b, g, and d) with activity against mTOR. Broad kinase selectivity profiling of >130 protein kinases revealed that XL765 is highly selective for class I PI3Ks and mTOR over other kinases. In cellular assays, XL765 inhibits the formation of PIP 3 in the membrane, and inhibits phosphorylation of AKT, p70S6K, and S6 phosphorylation in multiple tumor cell lines with different genetic alterations affecting the PI3K pathway. In a panel of tumor cell lines, XL765 inhibits proliferation with a wide range of potencies, with evidence of an impact of genotype on sensitivity. In mouse xenograft models, oral administration of XL765 results in dose-dependent inhibition of phosphorylation of AKT, p70S6K, and S6 with a duration of action of approximately 24 hours. Repeat dose administration of XL765 results in significant tumor growth inhibition in multiple human xenograft models in nude mice that is associated with antiproliferative, antiangiogenic, and proapoptotic effects. Mol Cancer Ther; 13(5); 1078-91. Ó2014 AACR.

The Selective PI3K Inhibitor XL147 (SAR245408) Inhibits Tumor Growth and Survival and Potentiates the Activity of Chemotherapeutic Agents in Preclinical Tumor Models

“…Kinase inhibition assays and the PIP 3 mass balance assay were performed as previously described (14).…”

“…pAKT and pS6 ELISA ELISA for pAKT T308 and total AKT were performed on PC-3 cell lysates and analyzed as previously described (14). The pS6 ELISA was performed as previously described (15) with minor modifications.…”

“…Cell lines were obtained from the ATCC in 2001-2005 and maintained in culture conditions at 37 C under 5% CO 2 as previously described (14). For PI3K pathway status assessment following EGF treatment, the culture medium was replaced with test compounds dissolved in serum-free DMEM containing 0.3% DMSO.…”

“…For PI3K pathway status assessment following EGF treatment, the culture medium was replaced with test compounds dissolved in serum-free DMEM containing 0.3% DMSO. After incubation for 3 hours, cells were stimulated with 100 ng/mL of EGF (R&D Systems, 236-EG) for 10 minutes and Western immunoblot analysis of cell lysates was performed as previously described (14). Assessment of mTOR pathway status in Ramos cells was performed as previously described (14).…”

“…After incubation for 3 hours, cells were stimulated with 100 ng/mL of EGF (R&D Systems, 236-EG) for 10 minutes and Western immunoblot analysis of cell lysates was performed as previously described (14). Assessment of mTOR pathway status in Ramos cells was performed as previously described (14). Cellular proliferation was assessed as previously described (16) using the Cell Proliferation ELISA, bromodeoxyuridine (BrdUrd) chemiluminescence kit (Roche, Applied Science).…”