Chapter 12 Liposome-Mediated Therapy of Neuroblastoma

Neuroblastoma-targeted nanoparticles and novel nanotechnology-based treatment methods

Neuroblastoma is a complicated pediatric tumor, originating from the neural crest, which is the most prevalent in adrenal glands, but may rarely be seen in some other tissues as well. Studies are focused on developing new strategies through novel chemo- and immuno-therapeutic drug targets. Different types of oncogenes such as MYCN, tumor suppressor genes such as p53, and some structural genes such as vascular endothelial growth factor are considered as targets for neuroblastoma therapy. The individual expression patterns in NB cells make them appropriate for this purpose. The combined effect of nano-drug delivery systems and specific drug targets will result in lower systemic side effects, prolonged therapeutic effects, and improvements in the pharmacokinetic properties of the drugs. Some of these novel drug delivery systems with a focus on liposomes as carriers are also discussed. In this review, genes and protein products that are beneficial as drug targets in the treatment of neuroblastoma have been discussed.

The CAM Assay as an Alternative In Vivo Model for Drug Testing

In the last decade, the chicken chorioallantoic membrane (CAM) assay has been re-discovered in cancer research to study the molecular mechanisms of anti-cancer drug effects. Literature about the CAM assay as an alternative in vivo cancer xenograft model according to the 3R principles has exploded in the last 3 years. Following a summary of the basic knowledge about the chicken embryo, we compare advantages and disadvantages with the classical mouse xenograft model, exemplify established and innovative imaging techniques that are used in the CAM model, and give examples of its successful utilization for studying major hallmarks of cancer such as angiogenesis, proliferation, invasion, and metastasis.

Tumor regression and modulation of gene expression via tumor-targeted tocotrienol niosomes

AIM

To develop 6-O-palmitoyl-ascorbic acid-based niosomes targeted to transferrin receptor for intravenous administration of tocotrienols (T3) in breast cancer.

MATERIALS & METHODS

Niosomes were prepared using film hydration and ultrasonication methods. Transferrin was coupled to the surface of niosomes via chemical linker. Nanovesicles were characterized for size, zeta potential, morphology, stability and biological efficacy.

RESULTS

When evaluated in MDA-MB-231 cells, entrapment of T3 in niosomes caused 1.5-fold reduction in IC₅₀ value compared with nonformulated T3. In vivo, the average tumor volume of mice treated with tumor-targeted niosomes was 12-fold lower than that of untreated group, accompanied by marked downregulation of three genes involved in metastasis.

CONCLUSION

Findings suggested that tumor-targeted niosomes served as promising delivery system for T3 in cancer therapy.

A new fluorescence-based optical imaging method to non-invasively monitor hepatic myofibroblasts in vivo

BACKGROUND & AIMS

Currently, staging of fibrosis in preclinical rodent liver fibrosis models is achieved histologically. Many animals are used at multiple time-points to assess disease progression or therapeutic responses. Hepatic myofibroblasts promote liver fibrosis therefore quantifying these cells in vivo could assess disease or predict therapeutic responses in mice. We fluorescently labelled a single chain antibody (C1-3) that binds hepatic myofibroblasts to monitor fibrogenesis in vivo.

METHODS

CCl4 was used to induce acute liver injury in WT and cRel(-/-) mice. Bile duct ligation was used to model chronic fibrosis. Hepatic myofibroblasts were depleted using a liposome-drug delivery system or chemically with sulfasalazine. An IVIS® spectrum visualised fluorophore-conjugated C1-3 in vivo.

RESULTS

IVIS detection of fluorescently labelled-C1-3 but not a control antibody discriminates between fibrotic and non-fibrotic liver in acute and chronic liver fibrosis models. cRel(-/-) mice have a fibro-protective phenotype and IVIS signal is reduced in CCl4 injured cRel(-/-) mice compared to wild-type. In vivo imaging of fluorescently labelled-C1-3 successfully predicts reductions in hepatic myofibroblast numbers in fibrotic liver disease in response to therapy.

CONCLUSIONS

We report a novel fluorescence imaging method to assess murine hepatic myofibroblast numbers in vivo during liver fibrosis and after therapy. We also describe a novel liposomal antibody targeting system to selectively deliver drugs to hepatic myofibroblasts in vivo. C1-3 binds human hepatic myofibroblast therefore imaging labelled-C1-3 could be used for clinical studies in man to help stage fibrosis, demonstrate efficacy of drugs that promote hepatic myofibroblast clearance or predict early therapeutic responses.

LAY SUMMARY

In response to damage and injury scars develop in the liver and the main cell that makes the scar tissue is the hepatic myofibroblast (HM). C1-3 is an antibody fragment that binds to the scar forming HM. We have fluorescently labelled C1-3 and given it to mice that have either normal or scarred livers (which contain HM) and then used a machine called an in vivo imaging system (IVIS) that takes pictures of different wavelengths of light, to visualise the antibody binding to HM inside the living mouse. Using fluorescently labelled C1-3 we can assess HM numbers in the injured liver and monitor response to therapy. We have also used C1-3 to target drugs encapsulated in lipid carriers (liposomes) to the HM to kill the HM and reduce the liver disease.

Nanoparticle delivery of an SN38 conjugate is more effective than irinotecan in a mouse model of neuroblastoma

Neuroblastoma (NB) is the most common and deadly solid tumor in children. The majority of NB patients have advanced stage disease with poor prognosis, so more effective, less toxic therapy is needed. We developed a novel nanocarrier-based strategy for tumor-targeted delivery of a prodrug of SN38, the active metabolite of irinotecan. We formulated ultrasmall-sized (<100 nm) biodegradable poly(lactide)-poly(ethylene glycol) based nanoparticles (NPs) containing SN38 conjugated to tocopherol succinate (SN38-TS). Alternative dosing schedules of SN38-TS NPs were compared to irinotecan. Comparison of SN38-TS NPs (2 doses) with irinotecan (20 doses) showed equivalent efficacy but no cures. Comparison of SN38-TS NPs (8, 8, and 16 doses, respectively) to irinotecan (40 doses) showed that all SN38-TS NP regimens were far superior to irinotecan, and "cures" were obtained in all NP arms. SN38-TS NP delivery resulted in 200× the amount of SN38 in NB tumors at 4 hr post-treatment, compared to SN38 detected for the irinotecan arm; no toxicity was seen with NPs. We conclude that this SN38-TS NP formulation improved delivery, retention, and efficacy, without causing systemic toxicity.

Enhanced anti-tumor and anti-angiogenic efficacy of a novel liposomal fenretinide on human neuroblastoma

Neuroblastoma is an embryonal tumor originating from the simpatico-adrenal lineage of the neural crest. It approximately accounts for about 15% of all pediatric oncology deaths. Despite advances in multimodal therapy, metastatic neuroblastoma tumors at diagnosis remain a clinical challenge. Retinoids are a class of compounds known to induce both terminal differentiation and apoptosis/necrosis of neuroblastoma cells. Among them, fenretinide (HPR) has been considered one of the most promising anti-tumor agent but it is partially efficacious due to both poor aqueous solubility and rapid metabolism. Here, we have developed a novel HPR formulation, by which the drug was encapsulated into sterically stabilized nanoliposomes (NL[HPR]) according to the Reverse Phase Evaporation method. This procedure led to a higher structural integrity of liposomes in organic fluids for a longer period of time, in comparison with our previous liposomal formulation developed by the film method. Moreover, NL[HPR] were further coupled with NGR peptides for targeting the tumor endothelial cell marker, aminopeptidase N (NGR-NL[HPR]). Orthotopically xenografted neuroblastoma-bearing mice treated with NGR-NL[HPR] lived statistically longer than mice untreated or treated with free HPR (NGR-NL[HPR] vs both control and HPR: P<0.0001). Also, NL[HPR] resulted in a statistically improved survival (NL[HPR] vs both control and HPR: P<0.001) but to a less extent if compared with that obtained with NGR-NL[HPR] (NGR-NL[HPR] vs NL[HPR]: P<0.01). Staining of tumor sections with antibodies specific for neuroblastoma and for either pericytes or endothelial cells evidenced that HPR reduced neuroblastoma growth through both anti-tumor and anti-angiogenic effects, mainly when delivered by NGR-NL[HPR]. Indeed, in this group of mice a marked reduction of tumor progression, of intra-tumoral vessel counts and VEGF expression, together with a marked down-modulation of matrix metalloproteinases MMP2 and MMP9, was observed. In conclusion, the use of this novel targeted delivery system for the apoptotic and antiangiogenic drug, fenretinide, could be considered as an adjuvant tool in the future treatment of neuroblastoma patients.

Second generation liposomal cancer therapeutics: transition from laboratory to clinic

Recent innovations and developments in nanotechnology have revolutionized cancer therapeutics. Engineered nanomaterials are the current workhorses in the emerging field of cancer nano-therapeutics. Lipid vesicles bearing anti-tumor drugs have turned out to be a clinically feasible and promising nano-therapeutic approach to treat cancer. Efficient entrapment of therapeutics, biocompatibility, biodegradability, low systemic toxicity, low immunogenicity and ability to bypass multidrug resistance mechanisms has made liposomes a versatile drug/gene delivery system in cancer chemotherapy. The present review attempts to explore the recent key advances in liposomal research and the vast arsenal of liposomal formulations currently being utilized in treatment and diagnosis of cancer.

Mechanisms of the antitumor activity of human Vγ9Vδ2 T cells in combination with zoledronic acid in a preclinical model of neuroblastoma

Low expression of surface major histocompatibility complex (MHC) class I molecules and defects in antigen processing machinery make human neuroblastoma (NB) cells appropriate targets for MHC unrestricted immunotherapeutic approaches. Human T-cell receptor (TCR) Vγ9Vδ2 lymphocytes exert MHC-unrestricted antitumor activity and are activated by phosphoantigens, whose expression in cancer cells is increased by aminobisphosphonates. With this background, we have investigated the in vivo anti-NB activity of human Vγ9Vδ2 lymphocytes and zoledronic acid (ZOL). SH-SY-5Y human NB cells were injected in the adrenal gland of immunodeficient mice. After 3 days, mice received ZOL or human Vγ9Vδ2 T cells or both agents by intravenous administration once a week for 4 weeks. A significantly improved overall survival was observed in mice receiving Vγ9Vδ2 T cells in combination with ZOL. Inhibition of tumor cell proliferation, angiogenesis and lymphangiogenesis, and increased tumor cell apoptosis were detected. Vγ9Vδ2 T lymphocytes were attracted to NB-tumor masses of mice receiving ZOL where they actively modified tumor microenvironment by producing interferon-γ (IFN-γ), that in turn induced CXCL10 expression in NB cells. This study shows that human Vγ9Vδ2 T cells and ZOL in combination inhibit NB growth in vivo and may provide the rationale for a phase I clinical trial in patients with high-risk NB.

Ferri-liposomes as an MRI-visible drug-delivery system for targeting tumours and their microenvironment

The tumour microenvironment regulates tumour progression and the spread of cancer in the body. Targeting the stromal cells that surround cancer cells could, therefore, improve the effectiveness of existing cancer treatments. Here, we show that magnetic nanoparticle clusters encapsulated inside a liposome can, under the influence of an external magnet, target both the tumour and its microenvironment. We use the outstanding T2 contrast properties (r2=573-1,286 s(-1) mM(-1)) of these ferri-liposomes, which are ∼95 nm in diameter, to non-invasively monitor drug delivery in vivo. We also visualize the targeting of the tumour microenvironment by the drug-loaded ferri-liposomes and the uptake of a model probe by cells. Furthermore, we used the ferri-liposomes to deliver a cathepsin protease inhibitor to a mammary tumour and its microenvironment in a mouse, which substantially reduced the size of the tumour compared with systemic delivery of the same drug.

Nanoparticles: Emerging carriers for drug delivery

The core objective of nanoparticles is to control and manipulate biomacromolecular constructs and supramolecular assemblies that are critical to living cells in order to improve the quality of human health. By definition, these constructs and assemblies are nanoscale and include entities such as drugs, proteins, DNA/RNA, viruses, cellular lipid bilayers, cellular receptor sites and antibody variable regions critical for immunology and are involved in events of nanoscale proportions. The emergence of such nanotherapeutics/diagnostics will allow a deeper understanding of human longevity and human ills that include cancer, cardiovascular disease and genetic disorders. A technology platform that provides a wide range of synthetic nanostructures that may be controlled as a function of size, shape and surface chemistry and scale to these nanotechnical dimensions will be a critical first step in developing appropriate tools and a scientific basis for understanding nanoparticles.