Activity of a novel dual PI3-kinase/mTOR inhibitor NVP-BEZ235 to enhance antitumor activities of gemcitabine and EMAP II in pancreatic cancer.

Abstract

255 Background: Gemcitabine (Gem, G) has limited benefits as single agent or in combination for pancreatic ductal adenocarcinomas (PDACs). The phosphatidylinositol-3-kinase (PI3K)/AKT and mammalian target of rapamycin (mTOR) signaling pathways are frequently dysregulated in diverse human cancers including PDAC. NVP-BEZ235 (BEZ, B) is a novel dual PI3K/mTOR inhibitor that has been shown to have antitumor activity in multiple tumor types. Endothelial monocyte activating polypeptide II (EMAP, E) is an antiendothelial and antiangiogenic agent that enhances Gem and docetaxel activity in PDAC. We tested the combination benefits of BEZ and Gem in addition to EMAP in experimental PDAC. Methods: In vitro cell proliferation and protein expression were analyzed by WST-1 assay and Western blotting. In vivo animal survival experiments were performed in NOD-SCID PDAC xenografts. Results: Cultured cells of PDAC (AsPC-1), endothelial (HUVECs), and fibroblast origin (WI-38) all expressed AKT and mTOR protein. BEZ inhibited in vitro cell proliferation of AsPC-1 and HUVECs cells, with some additive effects in combination with Gem or EMAP, after 72 hours of incubation. In AsPC-1, treatment of BEZ (100 nM), Gem (100 nM) and EMAP (1 μM) caused 34, -7, -16, 62, 51, 3, and 59 percent inhibition in proliferation in the B, G, E, B+G, B+E, G+E and B+G+E groups. In HUVECs, percent inhibition in proliferation was 35, 33, 15, 55, 35, 31 and 53 in the B, G, E, B+G, B+E, G+E and B+G+E groups, respectively. Compared to controls (median survival: 16 days), an animal survival increase after BEZ and EMAP therapy alone (both 21 days) and Gem therapy alone (28 d) was observed. Further increases in survival occurred in combination therapy groups B+G (30 d, p=0.007), B+E (27 d, p=0.02), G+E (31 d, p=0.001) and B+G+E (33 d, p=0.004). Conclusions: Bez has experimental PDAC antitumor activity in vitro and in vivo that is further enhanced by combination of Gem and EMAP. These findings demonstrate advantages of combination therapy strategies targeting multiple pathways in pancreatic cancer treatment. No significant financial relationships to disclose.