Abstract 2622: New therapeutic strategies in neuroblastoma: combined targeting of a novel tyrosine kinase inhibitor and liposomal siRNAs against ALK
Authors: Paolo Daniela D. , Emionite Laura , Liu George , Cilli Michele , Fiore Annarita D. , Brignole Chiara , Liang Chris , Pastorino Fabio , Gibbons Jay , Ponzoni Mirco , Perri Patrizia 
Published: May 2015

Abstract
The anaplastic lymphoma kinase (ALK), a tyrosine kinase receptor involved in the genesis of several human cancers, is a promising therapeutic target in Neuroblastoma (NB). Many studies on sporadic cases with advanced NB have shown ALK mutated or highly expressed independently of its genetic status (mutated, amplified, wild-type) and its pivotal role in NB growth and survival. As ALK is currently considered a master driver of NB oncogenesis, the use of therapies inhibiting ALK represents a suitable treatment option.
The ALK inhibitor Crizotinib was recently approved for the treatment of advanced NSCLC patient. However, as often observed with kinase inhibitors, some patients develop acquired resistance in part due to genetic ALK mutations. To overcome this limitation a selective and more potent ALK inhibitor, X-396, was developed that is currently in phase I clinical trial in adult patients with advanced solid tumors, but it has not been tested in preclinical animal models of NB.
We have successfully employed a RNAi-mediated therapeutic approach to selectively knockdown ALK expression by using nanoliposomes entrapping siRNA and coupled with anti-GD2 antibodies to target NB cells. Our data demonstrate for the first time a role of ALK in NB-induced angiogenesis and in tumor invasion.
Here, we aimed to test whether the combination of the novel ALK kinase inhibitor X-396 with the liposome-based silencing of ALK could represent a powerful synergistic and or additive effect in NB xenografts to promote long-term survival.
In vitro, X-396 showed to be more effective than Crizotinib in inhibiting cell proliferation and in inducing cell death in both LAN-5 (R1275Q ALK mut, Crizotinib-sensitive) and SH-SY5Y (F1174L ALK mut, Crizotinib-resistant) cells.
Pharmacokinetic profiles of X-396 after multiple PO administration in NB-xenografts revealed a good bioavailability and a moderate half-life. Biodistribution study clearly indicated that the concentration of X-396 8h post-administration was 35 fold higher in the tumor site than in plasma. X-396 reduced the tumor volume in subcutaneous SH-SY5Y NB-model in a dose-dependent manner and it was more effective than Crizotinib when administered at the same concentration. In orthotopic xenografts of SH-SY5Y and LAN-5 cells, X-396 significantly increased life span. In combination studies, all effects were significantly improved in the mice treated with targeted liposomal formulation of ALK-siRNA and X-396 compared to untreated control mice or mice receiving the single agent treatments. In the latter studies, further enhancement of life span was obtained by increasing the X-396 dose. Moreover, the combined treatment was also proven to be effective in the SH-SY5Y-pseudometastatic model in determining long-term survivors. Our findings provide a rational basis to design innovative molecular-based combination of treatments for clinical application in NB.
Citation Format: Daniela Di Paolo, Laura Emionite, George Liu, Michele Cilli, Annarita Di Fiore, Chiara Brignole, Chris Liang, Fabio Pastorino, Jay Gibbons, Mirco Ponzoni, Patrizia Perri. New therapeutic strategies in neuroblastoma: combined targeting of a novel tyrosine kinase inhibitor and liposomal siRNAs against ALK. [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 2622. doi:10.1158/1538-7445.AM2014-2622