Abstract B10: Noninvasive pharmacodynamic markers of the dual mTORC1/2 inhibitor AZD2014 in combination with paclitaxel, in cisplatin-resistant ovarian carcinoma xenografts

Abstract

Abstract Background: The PI3K/AKT/mTOR pathway is known to regulate glucose metabolism, proliferation and apoptosis, hence the inhibition of mTOR is expected have impact on these important mechanisms of tumor growth and survival. Studies of cancer metabolism following mTOR inhibition reported to date have only been carried out on allosteric mTOR inhibitors which selectively inhibit the activity of mTORC1. The metabolic changes associated with dual mTORC1 and 2 inhibitions remain unknown. AZD2014 is a dual mTORC1/2 inhibitor. The aims of this study are to (i) examine the effects on tumor metabolism following mTORC1/2 inhibition alone and in combination with paclitaxel, (ii) to develop a non-invasive pharmacodynamic (PD) biomarker for tumor response. Methods: We investigated the effects of AZD2014 alone (A: 50mg/kg/3 days/week po), paclitaxel alone (P: 20mg/kg/1 day/week ip) and the combination of AZD2014 and paclitaxel (A+P: same doses) on tumor growth, signal transduction (pSer473-AKT, pSer240/244-S6) and apoptosis (cleaved PARP) in a cisplatin resistant ovarian (A2780CisR) carcinoma xenograft model following 2 weeks of treatment. Metabolic profiles of A2780CisR tumor extracts after 2 weeks of treatment were also measured by high resolution in vitro 1H- and 31P-MRS. In order to develop early non-invasive PD markers of tumor response, in vivo 1H-MRS before and after 3 days of treatment were also performed. Results: Growth and molecular response- Following two weeks of treatment, tumor volumes of the A2780CisR xenografts increased by 280±100% in A+P (p<0.05; compared to vehicle-controls (V)), 420±160% in A (not significant compared to V (ns)), 730±180% in P (ns) and 560±20% in V. Reduced pSer473-AKT and pSer240/244-S6 protein levels and increased cleaved-PARP expression were observed in A- and A+P-treated xenografts consistent with mTORC1/2 inhibition and induction of apoptosis, respectively. In vitro 1H- and 31P-MRS of tumor extracts- Similar significant increases in branched-chain amino acids (p<0.03), glutamine (p<0.002), tyrosine (p<0.0001), phenylalanine (p<0.02) and glucose (p<0.03) were found in A- and A+P-treated tumors when compared with V. Significant decreases in phosphocholine (PC, p<0.002), glycero-phosphocholine (GPC, p<0.002), phosphoethanolamine (PE, p<0.02) and ATP (p<0.003), together with reduced expression of choline kinase, were only seen in A+P-treated tumors. An increase in threonine (p<0.03) was only observed in P- and A+P-treated tumors compared with V. In vivo 1H-MRS- The reduction in phospholipid metabolites (PC, GPC and PE) following A+P treatment was confirmed in vivo with a significant decrease in the ratio of total choline/water signal (p=0.04) observed at the early time-point of 3 days of treatment. Conclusions: A+P is effective in preclinical ovarian tumors, with additive growth inhibition and increased apoptosis. Very few metabolic changes were observed in P-treated tumors compared with V. The non-phospholipid changes in the metabolic profiles of A- and A+P-treated tumors are consistent with previous findings where similar metabolic profiles were found following mTOR inhibition (1). A+P treatment also caused decreases in PC (associated with reduced choline kinase expression) and other choline-related metabolites and these phospholipid changes may have potential as surrogate non-invasive markers for determining tumor response following AZD2014 and paclitaxel combination treatment. (1) Lin et al. Cell Symposia: Angiogenesis, Metabolic Regulation, and Cancer Biology in association with VIB, Belgium 2012. This work is supported by the CR-UK and EPSRC Cancer Imaging Centre in association with the MRC and Department of Health (England) grants C1060/A10334 and C1060/A16464, NHS funding to the NIHR Biomedical Research Centre. MOL is an NIHR Senior Investigator. Citation Format: Anne-Christine LF Wong Te-Fong, Efthymia Papaevangelou, Martin O. Leach, Udai Banerji, Yuen-Li Chung. Noninvasive pharmacodynamic markers of the dual mTORC1/2 inhibitor AZD2014 in combination with paclitaxel, in cisplatin-resistant ovarian carcinoma xenografts. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr B10.