Abstract 5499: Preclinical evaluation of PI3K inhibitor BYL719 as a single agent and its synergism in combination with cisplatin or MEK inhibitor in nasopharyngeal carcinoma (NPC) using 3D cell culture system

Abstract

BYL719 is a novel specific inhibitor against the alpha-isoform of Class I PI3K that imposes impacts on AKT-mTOR signaling axis, thereby mediating relevant pathways such as MAPK, STAT3 and EGFR. The study aims to investigate the effects of BYL719 on nasopharyngeal carcinoma (NPC) which has a high prevalence in Southeast Asia, and its synergism on combination with cisplatin or MEK inhibitor. Six NPC cell lines including C666-1, CNE-2, HK1, HK1-EBV, HONE-1, HONE-1-LMP were selected for this preclinical study. All cell lines had a basal expression in both phosphorylated and total forms of Akt, mTOR and p70S6K which are the downstream pathways of PI3K. MTT assay was used to evaluate the cytotoxicity of BYL719 on NPC, cells were incubated in BYL719 with escalating concentration (10nM, 50nM, 0.1µM, 0.5µM, 1µM, 5µM and 10µM) for 48 or 72 hours in culture medium. The maximum growth inhibition was attained in 72 hours of BYL719 incubation, the IC50s of all cell lines with 72-hour BYL719 treatment were in micromolar range (C666-1=1.85µM, CNE-2=0.90µM, HONE-1=0.56µM, HONE-1-LMP=0.95µM, HK-1-EBV=1.50µM and HK-1=1.53µM). Two sensitive cell lines CNE-2 and HONE-1 were selected for further analysis on apoptosis, cell cycle and BYL719's synergistic effect by 3D cell culture system. After 72 hours of treatment, BYL719 up-regulated mTOR, EGFR, p-EGFR (Y1086), p-STAT3 (Y705) and p-p44/22 MAPK (T202/Y204) in CNE-2 but not in HONE-1, however, it down-regulates mTOR in HONE-1. This suggested that BYL719 is more effective to HONE-1 in inhibiting mTOR downstream pathways and accordingly anti-proliferation. HONE-1 was then used to examine the synergistic effect of BYL719 combined with cisplatin or MEK inhibitor (AZD6244). Drug treatment commenced 72 hours after cell plating and growth inhibition was determined by MTT assay on day 9. As supported by cell viability assay and western blot, strong synergistic effect was expressed when BYL719 was combined with AZD6244. In comparison with using BYL719 alone, there was a 2-fold increase in growth inhibition observed in combination of BYL719 and AZD6244. The combination indices (CI) of 0.6µM BYL719 plus 0.325µM AZD6244 and 0.6µM BYL719 plus 0.65µM AZD6244 are 0.17 and 0.13 respectively, indicating strong synergism in these drug combinations. On the other hand, there was also mild synergistic effect observed when BYL719 was combined with cisplatin, with CI of 0.585 for 0.6µM BYL719 plus 1.2µg/ml cisplatin. The growth inhibition for BYL719 combined with cisplatin was comparable to the effect of high dose cisplatin (1.2µg/ml) administration. BYL719 is effective in NPC growth inhibition, its synergistic effect with MEK inhibitor does provide a great advantage in NPC treatment and is worthwhile for further studies. Acknowledgement: This work is supported by Novartis * Denotes co-authorship. Citation Format: Hio Teng Cheong, Chi Hang Wong, Connie Wun Chun Hui, Anthony Tak Cheung Chan, Brigette Buig Yue Ma. Preclinical evaluation of PI3K inhibitor BYL719 as a single agent and its synergism in combination with cisplatin or MEK inhibitor in nasopharyngeal carcinoma (NPC) using 3D cell culture system. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5499. doi:10.1158/1538-7445.AM2014-5499

Concomitant inhibition of PI3K/mTOR signaling pathways boosts antiproliferative effects of lanreotide in bronchopulmonary neuroendocrine tumor cells

“…As mentioned previously for H720 cells, both p-ERK and ERK were decreased after combination treatment (BYL719 and everolimus plus lanreotide). The addition of lanreotide could possibly have resulted in the suppression of the MAPK feedback activation which, reportedly, monotreatment with BYL719 induces ( Wong et al, 2015 ). Cell death appeared to be induced in both H720 and H727 cells lines, as suggested by the significant rapid increase in BAX after 48 h. Expression of tumor suppressor FOXO1 which is located downstream of PI3K/mTOR was induced after combination treatment in both cell lines as well.…”

Combining MEK and SRC inhibitors for treatment of colorectal cancer demonstrate increased efficacy in vitro but not in vivo

“…Some of them have not translated into improvements in therapeutic outcomes, and others are in the early stages of clinical evaluation. Thus, Most combination strategies under investigation rely on preconceived notions of compensatory pathways (e.g., PI3K/AKT inhibitors added to MEK inhibitors [42,[48][49][50][51] inhibition of proteins upstream of or downstream from MEK [52]. We hypothesized that MEK-targeted therapy in patients with mCRC will be most effective when combined with other treatments, specifically, either chemotherapy or targeted therapy, that are identified using unbiased screening approaches.…”

The Potential of PIP3 in Enhancing Wound Healing

“…Western blot analysis was conducted to evaluate the impact of free PIP3 and the Qstarch/PIP3 complexes on the phosphorylation of AKT in BJ fibroblast cells. To ensure that Akt phosphorylation was the result of the biological activity of the administered PIP3 and was not reflective of endogenously generated PIP3, PI3K was inhibited by BYL-719 [52][53][54]. Subsequent to the inhibition, the cells were treated either with the Q-starch/PIP3 complexes or with free PIP3 for different times, i.e., 3, 24, and 48 h, to determine if reactivation of AKT was achieved.…”