Abstract 4342: The allosteric Akt inhibitor MK-2206 inhibits neuroblastoma tumor cell growth in vitro and in vivo

Abstract Background: Activated Akt in tumor tissue of NB patients is a marker of decreased event-free as well as overall survival. Our studies indicate activated Akt induces chemoresistance in NB cells and chemoresistance is a major problem in the treatment of Neuroblastoma (NB). The allosteric Akt inhibitor, MK-2206 inhibits the activation of the 3 Akt isoforms with IC50-Akt1 = 5.3nM, -Akt2 = 12nM and -Akt3 = 65nM. In this study we tested the effects of MK-2206 in vitro and in vivo pre-clinical models of NB. Methods: NB cell lines (NGP, SY5Y, KCNR, BE2, SKNFI, and AS) were treated with increasing concentrations of MK-2206 for 48 hours. MK-2206-induced cell death was evaluated by MTS assay. Phosphorylated Akt and its downstream target S6 were determined by Western Blot analysis. The effect of MK-2206 (100 or 200mg/kg/3 days/wk) on NB tumor growth was evaluated in a xenograft nude mouse model. Results: NB cell lines express all 3 Akt isoforms to varying levels. In in vitro studies, MK-2206 inhibited cell growth in all NB cell lines although with different sensitivities. The growth of NGP, SY5Y, KCNR and BE2 cells were more sensitive to MK-2206, with IC50<4μM; while the growth of AS and SKNFI were less sensitive, with IC50>11μM. MK-2206 treatment decreased phosphorylated-Akt and its target phosphorylated-S6 in NB cells to a comparable level in all tested cell lines regardless of biologic sensitivity to MK-2206. In in vivo studies, mice bearing the sensitive BE2 NB tumors were treated with MK-2206 (100 or 200mg/kg) while mice bearing the less sensitive AS tumors received MK-2206 (200mg/kg). There was an approx. 30% inhibition of tumor growth in each tumor model only in mice treated with 200mg/kg MK-2206 (P<0.01). MK-2206 (200mg/kg) treatment led to a comparable increase in survival in both models (P<0.01). Conclusion: This study indicates that despite differences in in vitro growth sensitivities, the Akt inhibitor, MK-2206 has a comparable anti-tumor cell growth inhibiting activity in vivo. This study supports the future evaluation of the combination of MK-2206 with chemotherapeutic drugs to improve the treatment efficacy in NB. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4342. doi:10.1158/1538-7445.AM2011-4342