Hard-Shelled Glycol Chitosan Nanoparticles for Dual MRI/US Detection of Drug Delivery/Release: A Proof-of-Concept Study

This paper describes a novel nanoformulation for dual MRI/US in vivo monitoring of drug delivery/release. The nanosystem was made of a perfluoropentane core coated with phospholipids stabilized by glycol chitosan crosslinked with triphosphate ions, and it was co-loaded with the prodrug prednisolone phosphate (PLP) and the structurally similar MRI agent Gd-DTPAMA-CHOL. Importantly, the in vitro release of PLP and Gd-DTPAMA-CHOL from the nanocarrier showed similar profiles, validating the potential impact of the MRI agent as an imaging reporter for the drug release. On the other hand, the nanobubbles were also detectable by US imaging both in vitro and in vivo. Therefore, the temporal evolution of both MRI and US contrast after the administration of the proposed nanosystem could report on the delivery and the release kinetics of the transported drug in a given lesion.

Exploring chitosan-shelled nanobubbles to improve HER2 + immunotherapy via dendritic cell targeting

Immunotherapy is a valuable approach to cancer treatment as it is able to activate the immune system. However, the curative methods currently in clinical practice, including immune checkpoint inhibitors, present some limitations. Dendritic cell vaccination has been investigated as an immunotherapeutic strategy, and nanotechnology-based delivery systems have emerged as powerful tools for improving immunotherapy and vaccine development. A number of nanodelivery systems have therefore been proposed to promote cancer immunotherapy. This work aims to design a novel immunotherapy nanoplatform for the treatment of HER2 + breast cancer, and specially tailored chitosan-shelled nanobubbles (NBs) have been developed for the delivery of a DNA vaccine. The NBs have been functionalized with anti-CD1a antibodies to target dendritic cells (DCs). The NB formulations possess dimensions of approximately 300 nm and positive surface charge, and also show good physical stability up to 6 months under storage at 4 °C. In vitro characterization has confirmed that these NBs are capable of loading DNA with good encapsulation efficiency (82%). The antiCD1a-functionalized NBs are designed to target DCs, and demonstrated the ability to induce DC activation in both human and mouse cell models, and also elicited a specific immune response that was capable of slowing tumor growth in mice in vivo. These findings are the proof of concept that loading a tumor vaccine into DC-targeted chitosan nanobubbles may become an attractive nanotechnology approach for the future immunotherapeutic treatment of cancer.

Molecularly imprinted cyclodextrin nanosponges for the controlled delivery of L-DOPA: perspectives for the treatment of Parkinson's disease

BACKGROUND

L-DOPA is an amino acid precursor to the neurotransmitter dopamine that is extensively used as a prodrug for the treatment of Parkinson's disease. However, L-DOPA is an unstable compound: when exposed to light or added to aqueous solutions, it may degrade, compromising its therapeutic properties.

METHODS

In this work, a new type of drug-loaded cyclodextrin-based nanosponge, obtained using molecular imprinting, is described for the prolonged and controlled release of L-DOPA. The molecularly imprinted nanosponges (MIP-NSs) were synthesized by cross-linking β-cyclodextrin with 1,1'-carbonyldiimidazole in DMF in the presence of L-DOPA as a template molecule. TGA, DSC and FTIR analyses were performed to characterize the interactions between L-DOPA and the two nanosponge structures. Quantitative NMR spectroscopy was used to determine the amount and the affinity of L-DOPA entrapped in the nanosponges. The in vitro L-DOPA release kinetics from the NSs were quantitatively determined by HPLC analysis.

RESULTS

The MIP-NSs show a slower and more prolonged release profile than the non-imprinted nanosponges. No degradation of the L-DOPA hosted in the MIP-NSs was observed after long-term storage at room temperature.

CONCLUSIONS

The MIP-NSs are a promising alternative for the storage and controlled delivery of L-DOPA.

Dextran-shelled oxygen-loaded nanodroplets reestablish a normoxia-like pro-angiogenic phenotype and behavior in hypoxic human dermal microvascular endothelium

In chronic wounds, hypoxia seriously undermines tissue repair processes by altering the balances between pro-angiogenic proteolytic enzymes (matrix metalloproteinases, MMPs) and their inhibitors (tissue inhibitors of metalloproteinases, TIMPs) released from surrounding cells. Recently, we have shown that in human monocytes hypoxia reduces MMP-9 and increases TIMP-1 without affecting TIMP-2 secretion, whereas in human keratinocytes it reduces MMP-2, MMP-9, and TIMP-2, without affecting TIMP-1 release. Provided that the phenotype of the cellular environment is better understood, chronic wounds might be targeted by new oxygenating compounds such as chitosan- or dextran-shelled and 2H,3H-decafluoropentane-cored oxygen-loaded nanodroplets (OLNs). Here, we investigated the effects of hypoxia and dextran-shelled OLNs on the pro-angiogenic phenotype and behavior of human dermal microvascular endothelium (HMEC-1 cell line), another cell population playing key roles during wound healing. Normoxic HMEC-1 constitutively released MMP-2, TIMP-1 and TIMP-2 proteins, but not MMP-9. Hypoxia enhanced MMP-2 and reduced TIMP-1 secretion, without affecting TIMP-2 levels, and compromised cell ability to migrate and invade the extracellular matrix. When taken up by HMEC-1, nontoxic OLNs abrogated the effects of hypoxia, restoring normoxic MMP/TIMP levels and promoting cell migration, matrix invasion, and formation of microvessels. These effects were specifically dependent on time-sustained oxygen diffusion from OLN core, since they were not achieved by oxygen-free nanodroplets or oxygen-saturated solution. Collectively, these data provide new information on the effects of hypoxia on dermal endothelium and support the hypothesis that OLNs might be used as effective adjuvant tools to promote chronic wound healing processes.

The combination of sorafenib and everolimus shows antitumor activity in preclinical models of malignant pleural mesothelioma

Background

Malignant Pleural Mesothelioma (MPM) is an aggressive tumor arising from mesothelial cells lining the pleural cavities characterized by resistance to standard therapies. Most of the molecular steps responsible for pleural transformation remain unclear; however, several growth factor signaling cascades are known to be altered during MPM onset and progression. Transducers of these pathways, such as PIK3CA-mTOR-AKT, MAPK, and ezrin/radixin/moesin (ERM) could therefore be exploited as possible targets for pharmacological intervention. This study aimed to identify ‘druggable’ pathways in MPM and to formulate a targeted approach based on the use of commercially available molecules, such as the multikinase inhibitor sorafenib and the mTOR inhibitor everolimus.

Methods

We planned a triple approach based on: i) analysis of immunophenotypes and mutational profiles in a cohort of thoracoscopic MPM samples, ii) in vitro pharmacological assays, ii) in vivo therapeutic approaches on MPM xenografts. No mutations were found in ‘hot spot’ regions of the mTOR upstream genes (e.g. EGFR, KRAS and PIK3CA).

Results

Phosphorylated mTOR and ERM were specifically overexpressed in the analyzed MPM samples. Sorafenib and everolimus combination was effective in mTOR and ERM blockade; exerted synergistic effects on the inhibition of MPM cell proliferation; triggered ROS production and consequent AMPK-p38 mediated-apoptosis. The antitumor activity was displayed when orally administered to MPM-bearing NOD/SCID mice.

Conclusions

ERM and mTOR pathways are activated in MPM and ‘druggable’ by a combination of sorafenib and everolimus. Combination therapy is a promising therapeutic strategy against MPM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1363-1) contains supplementary material, which is available to authorized users.

Abstract 1163: Microenvironment targets in KRAS-mutated metastatic colorectal cancer

The introduction of biodrugs, e.g. the anti-EGFR antibodies, was initially seen as a promise to radically change the landscape for patients with metastatic colorectal cancer. However, although EGFR-targeted therapies, combined with chemotherapy, have prolonged survival expectancy to 24 months, cure remains anecdotal. Target therapies suffer of high costs, important side effects, and low response rates: it is now clear that this approach as it was originally conceived failed to meet the majority of its expectations. Importantly, because of novel prescription guidelines, patients with KRAS-mutated tumors are excluded from EGFR-targeted therapies: for these patients alternative treatments are urgently needed.

We here propose an innovative strategy based on the identification of molecular targets specifically associated with the microenvironment of metastatic colorectal cancer in patients carrying oncogenic KRAS. For this purpose, we set up mice models of metastatic colorectal cancer by intrasplenic (to evaluate liver homing) and intrahepatic (to investigate liver colonization) implantation of human colorectal cancer cell lines (SW48 and LIM1215) in which oncogenic KRAS (G12D, G12V, G13D) variants have been somatically knocked-in. We based our “target fishing” strategy on high-throughput, phage display-mediated proteomic screenings of deriving tumor samples ex vivo. Proteome signatures from the cognate cell lines in vitro served as a subtractive reference for the ex vivo biopanning, aimed at the identification of peptide ligands specific for non-epithelial components. By this combined biological-genetic-bioinformatics approach, we identified peptide/protein signatures selectively associated to metastasis microenvironments with controlled genetic backgrounds in vitro and in vivo.

We selected 2 target proteins and 2 targeting peptides, which were exploited for diagnostic and therapeutic purposes. First, we evaluated by IHC the presence and localization of the target proteins in samples (tumor, healthy liver) from a panel of human biopsies and from the described in vivo models. This analysis confirmed a specific enrichment in KRAS-mutated microenvironments. Second, we tested the capability of dye-conjugated targeting peptides to home to these same tumor microenvironments, observing a specific accumulation in target tissues, compared to their scrambled versions and to control tissues. Third, we investigated a potential anti-metastatic effect of these peptides when orthotopically co-injected with colorectal cancer cell lines; preliminary experiments revealed that the targeting peptides, but not the scrambled variants, inhibit the onset of liver metastases from KRAS-mutated cell lines.

In summary, we obtained proof-of-concept results in preclinical studies and produced prototype compounds to provide innovative tools that can be translated into the clinical practice with a mid-term perspective.

Citation Format: Serena Marchio, Alice Bartolini, Sabrina Cardaci, Marco Soster, Giorgio Corti, Simona Lamba, Federico Bussolino, Davide Cora', Federica Di Nicolantonio. Microenvironment targets in KRAS-mutated metastatic colorectal cancer. [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 1163. doi:10.1158/1538-7445.AM2014-1163

Novel phage display-derived neuroblastoma-targeting peptides potentiate the effect of drug nanocarriers in preclinical settings

Molecular targeting of drug delivery nanocarriers is expected to improve their therapeutic index while decreasing their toxicity. Here we report the identification and characterization of novel peptide ligands specific for cells present in high-risk neuroblastoma (NB), a childhood tumor mostly refractory to current therapies. To isolate such targeting moieties, we performed combined in vitro/ex-vivo phage display screenings on NB cell lines and on tumors derived from orthotopic mouse models of human NB. By designing proper subtractive protocols, we identified phage clones specific either for the primary tumor, its metastases, or for their respective stromal components. Globally, we isolated 121 phage-displayed NB-binding peptides: 26 bound the primary tumor, 15 the metastatic mass, 57 and 23 their respective microenvironments. Of these, five phage clones were further validated for their specific binding ex-vivo to biopsies from stage IV NB patients and to NB tumors derived from mice. All five clones also targeted tumor cells and vasculature in vivo when injected into NB-bearing mice. Coupling of the corresponding targeting peptides with doxorubicin-loaded liposomes led to a significant inhibition in tumor volume and enhanced survival in preclinical NB models, thereby paving the way to their clinical development.

Abstract 5620: Novel phage display-derived neuroblastoma-targeting peptides potentiate the effect of drug nanocarriers in preclinical settings

Purpose: Molecular targeting of drug delivery nanocarriers is expected to improve their therapeutic index while decreasing their toxicity. The identification of novel peptide ligands specific for cells present in high-risk neuroblastoma, a childhood tumor mostly refractory to current therapies, is needed.

Experimental design: We performed combined in vitro/ex-vivo phage display screenings on human neuroblastoma cell lines and on tumors derived from orthotopic mouse models of human neuroblastoma. Binding validation and homing in vivo of selected phage clones were tested by immunohistochemistry/immunofluorescent analyses. Cell association experiments in vitro with the corresponding synthetic biotin-labeled peptides were performed. In vitro cytotoxicity and in vivo tumor accumulation and therapeutic experiments were performed using peptide-targeted, doxorubicin-loaded, nanocarriers.

Results: By designing proper subtractive protocols, we identified phage clones specific either for the primary tumor, its metastases, or for the stromal components. Globally, we isolated 121 phage-displayed neuroblastoma-binding peptides; of these, 26 bound the primary tumor, 15 the metastatic mass, 57 and 23 their respective microenvironments. Of these, five phage clones were further validated for their specific binding ex-vivo to biopsies from stage IV neuroblastoma patients and to neuroblastoma tumors derived from mice. All five clones also targeted tumor cells and vasculature in vivo when injected into neuroblastoma-bearing mice. Coupling of the corresponding targeting peptides with doxorubicin-loaded nanocarriers led to a significant inhibition in tumor volume and enhanced survival in preclinical neuroblastoma models.

Conclusions: Our findings demonstrate that novel ligands of neuroblastoma-associated markers are functional in the design of nanocarriers with therapeutic efficacy paving the way to their clinical development.

Citation Format: Monica Loi, Daniela Di Paolo, Marco Soster, Chiara Brignole, Alice Bartolini, Laura Emionite, Jessica Sun, Pamela Becherini, Flavio Curnis, Andrea Petretto, Monica Sani, Alessandro Gori, Claudio Gambini, Renato Longhi, Michele Cilli, Theresa M. Allen, Federico Bussolino, Wadih Arap, Renata Pasqualini, Angelo Corti, Mirco Ponzoni, Serena Marchiò, Fabio Pastorino. Novel phage display-derived neuroblastoma-targeting peptides potentiate the effect of drug nanocarriers in preclinical settings. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5620. doi:10.1158/1538-7445.AM2013-5620

The Combination of Sorafenib and Everolimus Abrogates mTORC1 and mTORC2 upregulation in osteosarcoma preclinical models

PURPOSE

The multikinase inhibitor sorafenib displays antitumor activity in preclinical models of osteosarcoma. However, in sorafenib-treated patients with metastatic-relapsed osteosarcoma, disease stabilization and tumor shrinkage were short-lived and drug resistance occurred. We explored the sorafenib treatment escape mechanisms to overcome their drawbacks.

EXPERIMENTAL DESIGN

Immunoprecipitation, Western blotting, and immunohistochemistry were used to analyze the mTOR pathway [mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2)]. Cell viability, colony growth, and cell migration were evaluated in different osteosarcoma cell lines (MNNG-HOS, HOS, KHOS/NP, MG63, U-2OS, SJSA-1, and SAOS-2) after scalar dose treatment with sorafenib (10-0.625 μmol/L), rapamycin-analog everolimus (100-6.25 nmol/L), and combinations of the two. Cell cycle, reactive oxygen species (ROS) production, and apoptosis were assessed by flow cytometry. Nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice injected with MNNG-HOS cells were used to determine antitumor and antimetastatic effects. Angiogenesis and vascularization were evaluated in vitro by exploiting endothelial branching morphogenesis assays and in vivo in xenografted mice and chorioallantoic membranes.

RESULTS

After sorafenib treatment, mTORC1 signaling was reduced (downstream target P-S6), whereas mTORC2 was increased (phospho-mTOR Ser2481) in MNNG-HOS xenografts compared with vehicle-treated mice. Combining sorafenib with everolimus resulted in complete abrogation of both mTORC1 [through ROS-mediated AMP-activated kinase (AMPK) activation] and mTORC2 (through complex disassembly). The sorafenib/everolimus combination yielded: (i) enhanced antiproliferative and proapoptotic effects, (ii) impaired tumor growth, (iii) potentiated antiangiogenesis, and (iv) reduced migratory and metastatic potential.

CONCLUSION

mTORC2 activation is an escape mechanism from sorafenib treatment. When sorafenib is combined with everolimus, its antitumor activity is increased by complete inhibition of the mTOR pathway in the preclinical setting.

Preclinical evidence of ET-743 as a potential chemotherapy option for the treatment of biliary carcinoma

193

Background: The standard chemotherapy for unresectablebiliary tract carcinoma (BTC) is based on gemcitabine and platinum compounds. However, these combinations have not been shown to be effective in improving long-term survival. Thus, there is a real need to find new strategies that would impact in a significant way on clinical outcome. Ecteinascidin-743 (ET-743), a compound isolated from the marine tunicate Ecteinascidia turbinata. ET-743, is approved for the treatment of ovarian cancer and soft tissue sarcoma. Phase II and III clinical trials are ongoing for the treatment of different solid tumors. No preclinical data are available about the efficacy of ET-743 in BTC. In a phase I study, one patient received ET-743 plus capecitabine and experienced a long lasting complete metabolic response. Here, we investigated the antitumor activity of ET-743 in preclinical BTC models. Methods: Four BTC cell lines TFK1, EGI-1, HuH28 and TGBC1 were used to evaluate the effect of ET-743 on proliferation, cell cycle, apoptosis and on the activation of DNA damage proteins. The effect on proliferation was also investigated on a primary cell culture of a gallbladder carcinoma (GBC) resistant to gemcitabine and oxaliplatin. On the same cells, the inhibition of VEGF secretion mediated by ET-743 was analyzed by ELISA. The anti-tumor activity of ET-743 was tested on EGI-1 xenografts in NOD/SCID mice. Results: In vitro, ET-743 is able to markedly reduce cell proliferation of BTC cell lines through cell cycle blockage on G0/G1 phase and to inhibit the growth of primary cell culture derived from GBC patient. Moreover, ET-743 promotes apoptosis by caspase 3 activation, activates proteins involved in DNA damage and reduces VEGF secretion. In the in vivo model, ET-743 is able to slow tumor growth in BTC xenograft. The mechanism of anti-tumor activity involves DNA damage, the induction of hypoxia transcription factor-1, and angiogenesis inhibition. ET-743 has no significant effect on apoptosis in vivo. Conclusions: These data suggest that ET-743 could represent an alternative chemotherapy for BTC treatment and encourage the development of clinical trials of ET-743 in BTC patients.

A complex of α6 integrin and E-cadherin drives liver metastasis of colorectal cancer cells through hepatic angiopoietin-like 6

Homing of colorectal cancer (CRC) cells to the liver is a non-random process driven by a crosstalk between tumour cells and components of the host tissue. Here we report the isolation of a liver metastasis-specific peptide ligand (CGIYRLRSC) that binds a complex of E-cadherin and α(6) integrin on the surface of CRC cells. We identify angiopoietin-like 6 protein as a peptide-mimicked natural ligand enriched in hepatic blood vessels of CRC patients. We demonstrate that an interaction between hepatic angiopoietin-like 6 and tumoural α(6) integrin/E-cadherin drives liver homing and colonization by CRC cells, and that CGIYRLRSC inhibits liver metastasis through interference with this ligand/receptor system. Our results indicate a mechanism for metastasis whereby a soluble factor accumulated in normal vessels functions as a specific ligand for circulating cancer cells. Consistently, we show that high amounts of coexpressed α(6) integrin and E-cadherin in primary tumours represent a poor prognostic factor for patients with advanced CRC.

Targeted dual-color silica nanoparticles provide univocal identification of micrometastases in preclinical models of colorectal cancer

Background and methods

Despite the recent introduction of targeted bio-drugs, the scarcity of successful therapeutic options for advanced colorectal cancer remains a limiting factor in patient management. The efficacy of curative surgical interventions can only be extended through earlier detection of metastatic foci, which is dependent on both the sensitivity and specificity of the diagnostic tools.

Results

We propose a high-performance imaging platform based on silica-poly(ethylene glycol) nanoparticles doped with rhodamine B and cyanine 5. Simultaneous detection of these dyes is the basis for background subtraction and signal amplification, thus providing high-sensitivity imaging. The functionalization of poly(ethylene glycol) tails on the external face of the nanoparticles with metastasis-specific peptides guarantees their homing to and accumulation at target tissues, resulting in specific visualization, even of submillimetric metastases.

Conclusions

The results reported here demonstrate that our rationally designed modular nanosystems have the ability to produce a breakthrough in the detection of micrometastases for subsequent translation to clinics in the immediate future.

Abstract LB-366: Everolimus (EV) potentiates Sorafenib (SOR)activity in osteosarcoma (OS) preclinical models: a combination targeting the crosstalk between ERK1/2 and mTORC1/2 signaling pathways

OS is the most frequent primary bone tumor in children and young adults.The mammalian Target of Rapamycin (mTOR) and the Extracellular Regulated Kinases (ERK)1/2 pathways have been shown to cooperate in survival advantage of OS. Inhibition of this signaling can be a rational pharmacological strategy to impinge on OS progression. This study pursued the dual blockage of ERK1/2 and mTOR pathways by combining the multikinase inhibitor SOR with the rapamycin analog EV. The synergistic anti-profilerative effect was found against 5 out 7 OS cell lines (combination index<1, based on Chou-Talalay method). The inhibition of OS colony growth, due to cell cycle arrest and apoptosis induction was obtained. Mechanistically SOR alone, but EV, inhibited phospho-ERK1/2. EV and SOR as single agent induced the down-regulation of P-S6, P-4EBP. EV alone induced an increase in phospho-AKT as a consequence of the release of negative feed back by MTORC1 on MTORC2. Nonetheless, the combined treatment completely abrogated both ERK1/2 and MTORC1/2. The crosstalk among these pathways was interrupted by AMPK activation due to sorafenib-induced ROS burst and MTORC2 disassembling. The anti-tumoral activity and the inhibition of angiogenesis and metastasis in vivo were demonstrated against OS xenografts in NOD/SCID mice and in chicken chorioallantoic membrane model. A 28 daily oral gavage of mice (6/group) with SOR 5mg/kg, EV 1mg/kg, or their combination reduced tumor growth to 34%, 46%, and 29% of control slowing down cell proliferation and inducing apoptosis. In vivo model of OS metastasis obtained by e.v injection of OS cells confirmed the high metastatic potential of human OS consistently with the clinical experience. However, daily treatment of mice induced a significant reduction in number and size of lung metastases (foci area 65%, 74% and 29% of control obtained after 14 daily SOR, EV, and combined treatment). Anti-migratory effect was evidenced in 7 OS cell lines and was attributable to SRC/FAK/ERM pathway inhibition. HUVEC branching morphogenesis inhibition and reduction of blood vessel density in xenografts confirmed a strong potentiation of anti-angiogenic activity of drug combination. These results straighten our understanding of the networking nature of oncogenic signal transduction circuits in OS, therefore sustaining the rational for testing combination of sorafenib and everolimus in clinical setting.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-366. doi:1538-7445.AM2012-LB-366

Antitumor activity of Src inhibitor saracatinib (AZD-0530) in preclinical models of biliary tract carcinomas

Biliary tract carcinoma (BTC) has a poor prognosis due to limited treatment options. There is, therefore, an urgent need to identify new targets and to design innovative therapeutic approaches. Among potential candidate molecules, we evaluated the nonreceptor tyrosine kinase Src, observing promising antitumor effects of its small-molecule inhibitor saracatinib in BTC preclinical models. The presence of an active Src protein was investigated by immunohistochemistry in 19 surgical samples from patients with BTC. Upon saracatinib treatment, the phosphorylation of Src and of its downstream transducers was evaluated in the BTC cell lines TFK-1, EGI-1, HuH28, and TGBC1-TKB. The effect of saracatinib on proliferation and migration was analyzed in these same cell lines, and its antitumor activity was essayed in EGI-1 mouse xenografts. Saracatinib-modulated transcriptome was profiled in EGI-1 cells and in tumor samples of the xenograft model. Src was activated in about 80% of the human BTC samples. In cultured BTC cell lines, low-dose saracatinib counteracted the activation of Src and of its downstream effectors, increased the fraction of cells in G(0)-G(1) phase, and inhibited cell migration. At high concentrations (median dose from 2.26-6.99 μmol/L), saracatinib was also capable of inhibiting BTC cell proliferation. In vivo, saracatinib treatment resulted in delayed tumor growth, associated with an impaired vascular network. Here, we provide a demonstration that the targeted inhibition of Src kinase by saracatinib is of therapeutic benefit in preclinical models of BTC. We propose our results as a basis for the design of saracatinib-based clinical applications.

Abstract 3625: Novel phage-display derived peptides for tumor- and vasculature-targeted therapies in neuroblastoma

Disseminated neuroblastoma (NB) is refractory to most current therapeutic regimens. The therapeutic index of anticancer drugs is increased by liposome encapsulation and further improvements is obtained by coupling tumor-targeting ligands to the surface of the lipidic envelop. Phage display technology is a powerful tool in discovering novel ligands specific to receptors on the surface of tumor epithelial and endothelial cells. Therapeutic targeting to tumor blood vessels combines blood vessel destruction with the expected anti-tumor activities of the drug, resulting in increased efficacy and reduced toxicity.

To find NB-specific targeting moieties, we established a protocol for the isolation of heterogeneous cell populations by tissue fractionation of primary tumors and metastases from two models of human NB (with tumor cells injected either intravenously, to mimic minimal residual disease, or orthotopically in the adrenal gland of mice, to reflect the growth of advanced NB in children with large adrenal gland tumors and small metastatic lesions) and from stage IV, stroma poor, NB-derived specimens immediately after surgical removal. Cells extracted from corresponding healthy organs from mice and patients were used both in a negative pre-selection step and as a negative control for specific phage enrichment. The NB cell suspensions were subjected to multi-step screenings with the phage-displayed peptide library CX7C (where C = cysteine and X = any aminoacid). We globally isolated 135 NB-binding peptides. Of these, 31 were selected for binding to the primary tumor mass, 16 to the metastatic mass, 63 to tumor endothelial cells, and 25 to endothelial cells of metastases. Several proteins presenting sequence homology with the discovered peptides have been identified by BLAST analysis and were evaluated for their expression in NB tumors, derived from both mouse xenogratfs and patient specimens. Specifically, 5 novel phage display derived-peptides showed specific binding on NB specimens and homing to tumor cells and tumor vasculature, 10 minutes and 24 hours after injection through the tail vein of NB-bearing mice. We are testing the new molecular, tumor- and vasculature-specific peptides for generating novel tumor-specific liposomal therapies against NB. The availability of novel ligands binding to additional tumor-associated antigens and to targets on both endothelial and perivascular tumor cells will allow to design more sophisticated liposomal targeted anticancer strategies that exhibit high levels of selective toxicity for the cancer cells.

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 3625. doi:10.1158/1538-7445.AM2011-3625