Intranasal interleukin-12 gene therapy enhanced the activity of ifosfamide against osteosarcoma lung metastases

Circulating microRNAs and Cytokines as Prognostic Biomarkers for Doxorubicin-Induced Cardiac Injury and for Evaluating the Effectiveness of an Exercise Intervention

PURPOSE

To define a set of biomarkers that can be used to identify patients at high risk of developing late doxorubicin (DOX)-induced cardiac morbidity with the goal of focused monitoring and early interventions.

EXPERIMENTAL DESIGN

Mice received phosphate buffered saline or DOX 2.5 mg/kg 2x/week for 2 weeks. Blood samples were obtained before and after therapy for quantification of miRNAs (6 and 24 hours), cytokines (24 hours), and troponin (24 hours, 4 and 6 weeks). Cardiac function was evaluated using echocardiography before and 24 hours after therapy. To assess the effectiveness of exercise intervention in preventing DOX-induced cardiotoxicity blood samples were collected from mice treated with DOX or DOX + exercise. Plasma samples from 13 DOX-treated patients with sarcoma were also evaluated before and 24 hours after therapy.

RESULTS

Elevations in plasma miRNA-1, miRNA-499 and IL1α, IL1β, and IL6 were seen in DOX-treated mice with decreased ejection fraction and fractional shortening 24 hours after DOX therapy. Troponin levels were not elevated until 4 weeks after therapy. In mice treated with exercise during DOX, there was no elevation in these biomarkers and no change in cardiac function. Elevations in these biomarkers were seen in 12 of 13 patients with sarcoma treated with DOX.

CONCLUSIONS

These findings define a potential set of biomarkers to identify and predict patients at risk for developing acute and late cardiovascular diseases with the goal of focused monitoring and early intervention. Further studies are needed to confirm the predictive value of these biomarkers in late cardiotoxicity.

Local administration of IL-12 with an HC vector results in local and metastatic tumor control in pediatric osteosarcoma

Osteosarcoma is the most frequent and aggressive bone tumor in children and adolescents, with a long-term survival rate of 30%. Interleukin-12 (IL-12) is a potent cytokine that bridges innate and adaptive immunity, triggers antiangiogenic responses, and achieves potent antitumor effects. In this work, we evaluated the antisarcoma effect of a high-capacity adenoviral vector encoding mouse IL-12. This vector harbored a mifepristone-inducible system for controlled expression of IL-12 (High-Capacity adenoviral vector enconding the EF1α promoter [HCA-EFZP]-IL-12). We found that local administration of the vector resulted in a reduction in the tumor burden, extended overall survival, and tumor eradication. Moreover, long-term survivors exhibited immunological memory when rechallenged with the same tumor cells. Treatment with HCA-EFZP-IL-12 also resulted in a significant decrease in lung metastasis. Immunohistochemical analyses showed profound remodeling of the osteosarcoma microenvironment with decreases in angiogenesis and macrophage and myeloid cell numbers. In summary, our data underscore the potential therapeutic value of IL-12 in the context of a drug-inducible system that allows controlled expression of this cytokine, which can trigger a potent antitumor immune response in primary and metastatic pediatric osteosarcoma.

Recent advances in the management of osteosarcoma and forthcoming therapeutic strategies

Osteosarcoma is the most frequent primary bone tumor and occurs mainly in young patients (average age: 18 years). No evolution of the survival rates has been recorded for two decades in response to current treatment, associating often toxic and badly tolerated cures of chemotherapy (given a significant rate of bad responders) with preserving surgery. Among the proposed innovative strategies, immune-based therapy, antiangiogenesis agents, tumor-suppressor or suicide gene therapy, or anticancer drugs not commonly used in osteosarcoma are presented. A further strategy is to target the tumor microenvironment rather than the tumor itself.

The histone deacetylase inhibitor, MS-275 (entinostat), downregulates c-FLIP, sensitizes osteosarcoma cells to FasL, and induces the regression of osteosarcoma lung metastases

The purpose of this study was to determine the effects of the histone deacetylase inhibitor, MS-275, on the Fas signaling pathway and susceptibility of osteosarcoma (OS) to Fas ligand (FasL)-induced cell death. OS metastasizes almost exclusively to the lungs. We have shown that Fas expression in OS cells is inversely correlated with their metastatic potential. Fas(+) cells are rapidly eliminated when they enter the lungs via interaction with FasL, which is constitutively expressed in the lungs. Fas(-) OS cells escape this FasL-induced apoptosis and survive in the lung microenvironment. Moreover, upregulation of Fas in established OS lung metastases results in tumor regression. Therefore, agents that upregulate Fas expression or activate the Fas signaling pathway may have therapeutic potential. Treatment of Fas(-) metastatic OS cell lines with 2 µM MS-275 sensitized cells to FasL-induced cell death in vitro. We found that MS-275 did not alter the expression of Fas on the cell surface; rather it resulted in the downregulation of the anti-apoptotic protein, c-FLIP (cellular FLICE-inhibitory protein), by inhibiting c-FLIP mRNA. Downregulation of c- FLIP correlated with caspase activation and apoptosis induction. Treatment of nu/nu-mice with established OS lung metastases with oral MS-275 resulted in tumor regression, increased apoptosis and a significant inhibition of c-FLIP expression in tumors. Histopathological examination of mice showed no evidence of significant toxicity. Overall, these results suggest that the mechanism by which MS-275 sensitizes OS cells and lung metastases to FasL-induced cell death may be by a direct reduction in the expression of c-FLIP.

Participation of the Fas/FasL signaling pathway and the lung microenvironment in the development of osteosarcoma lung metastases

The lungs are the most common site for the metastatic spread of osteosarcoma. Success in using chemotherapy to improve overall survival has reached a plateau. Understanding the biologic properties that permit osteosarcoma cells to grow in the lungs may allow the identification of novel therapeutic approaches-the goal being to alter the tumor cells' expression of cell surface proteins so that there is no longer compatibility with the metastatic niche. We have demonstrated that the Fas Ligand positive (FasL(+)) lung microenvironment eliminates Fas(+) osteosarcoma cells that metastasize to the lungs. Indeed, osteosarcoma lung metastases from patients are Fas(-), similar to what we found in several different mouse models. The Fas(+) cells are cleared from the lungs through apoptosis induced by the Fas signaling pathway following interaction of Fas on the tumor cell surface with the lung FasL. Blocking the Fas signaling pathway interferes with this process, allowing the Fas(+) cells to grow in the lungs. Our investigations show that Fas expression in osteosarcoma cells is regulated epigenetically by the micro-RNA miR-20a, encoded by the miR-17-92 cluster. Our studies support the feasibility of finding agents that can re-induce Fas expression as a novel therapeutic approach to treat osteosarcoma patients with lung metastases. We have identified two such agents, the histone deacetylase inhibitor entinostat and the chemotherapeutic agent gemcitabine (GCB). Aerosol GCB and oral entinostat induce the upregulation of Fas and the regression of established osteosarcoma lung metastases. Aerosol GCB was not effective in the FasL-deficient gld mouse confirming that the lung microenvironment was central to the success of this therapy. Our studies establish the critical role of the lung microenvironment in the metastatic process of osteosarcoma to the lungs and suggest an alternative focus for therapy, that is, incorporating the lung microenvironment as part of the treatment strategy against established osteosarcoma disease in the lungs.

Using canine osteosarcoma as a model to assess efficacy of novel therapies: can old dogs teach us new tricks?

Since its domestication more than 10,000 years ago, the dog has been the animal that most intimately shares our work and homelife. Interestingly, the dog also shares many of our diseases including cancer such as osteosarcoma. Like the human, osteosarcoma is the most common bone malignancy of the dog and death from pulmonary metastasis is the most common outcome. The incidence of this spontaneous bone neoplasm occurs ten times more frequently that it does so in children with about 8,000-10,000 cases estimated to occur in dogs in the USA. Because there is no "standard of care" in veterinary medicine, the dog can also serve us by being a model for this disease in children. Although the most common therapy for the dog with osteosarcoma is amputation followed by chemotherapy, not all owners choose this route. Consequently, novel therapeutic interventions can be attempted in the dog with or without chemotherapy that could not be done in humans with osteosarcoma due to ethical concerns. This chapter will focus on the novel therapies in the dog that have been reported or are in veterinary clinical trials at the author's institution. It is hoped that collaboration between veterinary oncologists and pediatric oncologists will lead to the development of novel therapies for (micro- or macro-) metastatic osteosarcoma that improve survival and might ultimately lead to a cure in both species.

Inhaled gene therapy in lung cancer: proof-of-concept for nano-oncology and nanobiotechnology in the management of lung cancer

Lung cancer still remains one of the leading causes of death among cancer patients. Although novel targeted therapies have been established in everyday treatment practice, and conventional platinum-based doublets have demonstrated effective results regarding overall and progression-free survival, we have still failed to achieve long-term survival. Therefore, several strategies of applying locoregional therapy are under investigation. Aerosol chemotherapy is already under investigation and, taking this a step further, aerosol gene therapies with multiple delivery systems are being developed. Several efforts have demonstrated its efficiency and effectiveness, but there are still multiple factors that have to be considered and combined to achieve an overall more effective multifunctional treatment. In the current review, we present data regarding aerosol delivery systems, transporters, carriers, vectors, genes, toxicity, efficiency, specificity, lung microenvironment and delivery gene therapy systems. Finally, we present current studies and future perspectives.

Association of interleukin-12 polymorphisms and serum IL-12p40 levels with osteosarcoma risk

No previous studies reported the association of IL-12 polymorphisms with osteosarcoma. We aimed to investigate the association in a Chinese population. IL-12A rs568408, rs2243115, and IL-12B rs3212227 polymorphisms were evaluated in a case-control study of 106 osteosarcoma patients and 210 health controls by using polymerase chain reaction-restriction fragment length polymorphism. Serum IL-12p40 levels were measured by enzyme-linked immunosorbent assay. The serum IL-12p40 levels were significantly higher in controls than those in osteosarcoma patients (p<0.01). Genotypes of rs568408 GA and GA/AA, and rs3212227 CC and AC/CC were associated with the risk of osteosarcoma (rs568408 GA: odds ratios [OR]=1.86, 95% confidence intervals [CI]=1.11-3.12; GA/AA: OR=1.75, 95% CI=1.06-2.89, and rs3212227 CC: OR=2.70, 95% CI=1.38-5.28; CC/AC: OR=1.73, 95% CI=1.03-2.90). Moreover, rs3212227 CC/AC genotypes were significantly associated with decreased serum IL-12p40 levels in osteosarcoma patients compared to AA genotypes (p=0.035). Stratification analysis showed no associations between rs3212227 variant and the patients' gender, tumor location, and metastasis. Our data suggest that the serum IL-12p40 levels associate with the risk of osteosarcoma and are regulated by IL-12B rs3212227 polymorphism. The IL-12A rs568408 and IL-12B rs3212227 may confer the susceptibility to osteosarcoma risk.

Protein kinase C epsilon and genetic networks in osteosarcoma metastasis

Osteosarcoma (OS) is the most common primary malignant tumor of the bone, and pulmonary metastasis is the most frequent cause of OS mortality. The aim of this study was to discover and characterize genetic networks differentially expressed in metastatic OS. Expression profiling of OS tumors, and subsequent supervised network analysis, was performed to discover genetic networks differentially activated or organized in metastatic OS compared to localized OS. Broad trends among the profiles of metastatic tumors include aberrant activity of intracellular organization and translation networks, as well as disorganization of metabolic networks. The differentially activated PRKCε-RASGRP3-GNB2 network, which interacts with the disorganized DLG2 hub, was also found to be differentially expressed among OS cell lines with differing metastatic capacity in xenograft models. PRKCε transcript was more abundant in some metastatic OS tumors; however the difference was not significant overall. In functional studies, PRKCε was not found to be involved in migration of M132 OS cells, but its protein expression was induced in M112 OS cells following IGF-1 stimulation.

Vectors for inhaled gene therapy in lung cancer. Application for nano oncology and safety of bio nanotechnology

Novel aerosol therapeutic modalities have been investigated for lung cancer. Inhaled gene therapy has presented safety and effectiveness previously in cystic fibrosis. However, safety concerns have been raised regarding the safety of non-viral vectors for inhaled gene therapy in lung cancer, and therefore small steps have been made towards this multifunctional treatment modality. During the last decade, numerous new nanocomplexes have been created and investigated as a safe gene delivery nano-vehicle. These formulations are multifunctional; they can be used as either local therapy or carrier for an effective inhaled gene therapy for lung cancer. Herein, we present current and future perspectives of nanocomplexes for inhaled gene therapy treatment in lung cancer.

Therapeutic effect of recombinant plasmid-encoded human interleukin-12 in tumor-bearing mice

The aim of this study was to investigate the effects of gene therapy using a recombinant plasmid encoding human interleukin-12 (rIL-12, pcDNA6-p70) on transplanted tumors in mice. Tumor-bearing mice were transplanted with sarcoma‑180 (S-180) cells and randomly divided into three groups of 10 mice with each group receiving a separate treatment. Following this, pcDNA6-p70 (dissolved in purified water; 100 µg/mouse), cyclophosphamide (dissolved in 0.9% saline; 40 mg/kg) or 0.9% saline (100 µl/mouse) was directly injected into the tumors on the 4th, 7th, 10th, 14th and 17th days following transplantation of the S-180 cells. Mice survival time was monitored and surviving mice were sacrificed on the 21st day. In addition to survival time, tumor volume, NK cell activity, spleen lymphocyte proliferation and IFN-γ production were investigated. The mice were also monitored for any adverse effects regarding the administration of pcDNA6-p70. Our results demonstrated that pcDNA6-p70 prolongs the survival time of tumor-bearing mice, decreases tumor size (P<0.01) and increases the proliferative response of spleen cells, the activity of NK cells and the serum level of IFN-γ. There were no significant adverse effects caused by the administration of pcDNA6-p70. The results of the present study support the hypothesis that gene therapy using the rIL-12 plasmid exerts a therapeutic effect in tumor models by triggering antitumor cellular immunity.

Molecular alterations associated with osteosarcoma development

Osteosarcoma is the most frequent malignant primary bone tumor characterized by a high potency to form lung metastases which is the main cause of death. Unfortunately, the conventional chemotherapy is not fully effective on osteosarcoma metastases. The progression of a primary tumor to metastasis requires multiple processes, which are neovascularization, proliferation, invasion, survival in the bloodstream, apoptosis resistance, arrest at a distant organ, and outgrowth in secondary sites. Consequently, recent studies have revealed new insights into the molecular mechanisms of metastasis development. The understanding of the mechanism of molecular alterations can provide the identification of novel therapeutic targets and/or prognostic markers for osteosarcoma treatment to improve the clinical outcome.

miR-20a encoded by the miR-17-92 cluster increases the metastatic potential of osteosarcoma cells by regulating Fas expression

The ability of osteosarcoma cells to form lung metastases has been inversely correlated to cell surface Fas expression. Downregulation of Fas allows osteosarcoma cells to circumvent FasL-mediated apoptosis upon entrance into the FasL(+) lung microenvironment. However, the mechanism of Fas regulation remains unclear. Here, we show that miRNA plays a role in the downregulation of Fas expression in osteosarcoma. Expression levels of several members of the miR-17-92 cluster including miR-20a and miR-19a were found to be higher in metastatic low-Fas-expressing LM7 cells than in the parental nonmetastatic high-Fas-expressing SAOS-2 cells. We also found an inverse correlation between Fas and miR-20a expression in all 8 cell lines derived from patient samples. Overexpression of miR-20a consistently resulted in the downregulation of Fas expression in SAOS-2 cells and thus in decreased sensitivity to FasL. Conversely, inhibiting miR-20a in LM7 cells increased Fas expression and their sensitivity to FasL. Mice injected with LM7 stably transfected with anti-miR-20a had fewer metastases than those with control plasmids. Taken together, our findings suggest that miR-20a, encoded by miR-17-92, downregulates Fas expression in osteosarcoma, thus contributing to the metastatic potential of osteosarcoma cells by altering the phenotype and allowing survival in the FasL(+) lung microenvironment.

Molecular alterations as target for therapy in metastatic osteosarcoma: a review of literature

Treating metastatic osteosarcoma (OS) remains a challenge in oncology. Current treatment strategies target the primary tumour rather than metastases and have a limited efficacy in the treatment of metastatic disease. Metastatic cells have specific features that render them less sensitive to therapy and targeting these features might enhance the efficacy of current treatment. A detailed study of the biological characteristics and behaviour of metastatic OS cells may provide a rational basis for innovative treatment strategies. The aim of this review is to give an overview of the biological changes in metastatic OS cells and the preclinical and clinical efforts targeting the different steps in OS metastases and how these contribute to designing a metastasis directed treatment for OS.

Antitumoral efficacy of DNA nanoparticles in murine models of lung cancer and pulmonary metastasis

Polyethylenimine (PEI)-DNA complexes are nanoparticles that are able to efficiently transfer plasmids to the lungs. Interleukin-12 (IL12) gene transfer using PEI may represent an important strategy for lung cancer treatment. In this study, we evaluated the antitumoral efficacy of the administration of PEI-DNA nanoparticles carrying IL12 gene (PEI-IL12) for the treatment of lung cancer and pulmonary metastases in animal models. After inoculation of tumor cells, mice were treated intravenously with a single dose of PEI-IL12, PEI nanoparticles carrying the reporter gene beta-galactosidase (PEI-LacZ) or vehicle. Transgene expression, survival rates and immune response were analyzed in both models. Administration of PEI-LacZ and PEI-IL12 nanoparticles controlled tumor growth and prolonged survival times in both animal models. Although PEI-IL12 and PEI-LacZ administration showed similar antitumoral effects in the lung cancer model, the efficacy of PEI-IL12 was significantly superior in the inhibition of the development of pulmonary metastases. Furthermore, the administration of PEI-DNA nanoparticles results in the production of high levels of proinflammatory cytokines. Our results showed that PEI-DNA nanoparticles are an efficient vector for mediating gene transfer to the lungs, are a potent inducer of the innate immune response and represents an interesting strategy for the treatment of bronchogenic carcinoma and metastatic lung carcinoma.

Fas expression in metastatic osteosarcoma cells is not regulated by CpG island methylation

Fas expression in osteosarcoma (OS) cells is inversely correlated with the metastatic potential of OS to the lung. The purpose of this study was to determine whether loss of Fas expression in metastatic OS cells is secondary to DNA methylation of CpG islands in the Fas gene. SAOS-2 cells have high levels of Fas expression and do not form lung metastases when injected intravenously, whereas LM7 cells have low levels of Fas expression and do produce lung metastases. Using the endonucleases HpaII and MspI and a polymerase chain reaction-based methylation assay, we found that all four CpG sites in the CCGG sequence in the Fas promoter region were unmethylated in both SAOS-2 and LM7 cells. We performed detailed analysis of the 28 and 46 CpG sites in the Fas promoter and first intron region, respectively, using bisulfite-modified genomic DNA sequencing. More than 99.8% of the examined CpG sites were unmethylated and there was no difference of CpG methylation in SAOS-2 and LM7 cells as well as LM7 metastatic lung tumor tissue samples. Treatment of LM7 cells and another OS cell line, DLM8 with low levels of Fas expression, with demethylation agent, 5-azadeoxycitidine (AzadC), did not change the Fas expression and did not increase sensitivity of AzadC-treated cells to Fas ligand (FasL) treatment. In conclusion, our data indicate that decreased Fas expression in OS cells is not secondary to DNA methylation of CpG islands in the Fas gene and that Fas expression cannot be increased by using demethylation agents.

Polyethylenimine-mediated gene delivery to the lung and therapeutic applications

Nonviral gene delivery is now considered a promising alternative to viral vectors. Among nonviral gene delivery agents, polyethylenimine (PEI) has emerged as a potent candidate for gene delivery to the lung. PEI has some advantages over other polycations in that it combines strong DNA compaction capacity with an intrinsic endosomolytic activity. However, intracellular (mainly the nuclear membrane) and extracellular obstacles still hamper its efficiency in vitro and in vivo, depending on the route of administration and the type of PEI. Nuclear delivery has been increased by adding nuclear localization signals. To overcome nonspecific interactions with biological fluids, extracellular matrix components and nontarget cells, strategies have been developed to protect polyplexes from these interactions and to increase target specificity and gene expression. When gene delivery into airway epithelial cells of the conducting airways is necessary, aerosolization of complexes seems to be better suited to guarantee higher transgene expression in the airway epithelial cells with lower toxicity than observed with either intratracheal or intravenous administration. Aerosolization, indeed, is useful to target the alveolar epithelium and pulmonary endothelium. Proof-of-principle that PEI-mediated gene delivery has therapeutic application to some genetic and acquired lung disease is presented, using as genetic material either plasmidic DNA or small-interfering RNA, although optimization of formulation and delivery protocols and limitation of toxicity need further studies.

Is there a role for immunotherapy in osteosarcoma?

With the introduction of effective systemic chemotherapy, the prognosis for patients with osteosarcoma has improved dramatically. Estimates of overall survival for osteosarcoma patients prior to 1975 ranged from 5 to 20%, even for patients with localized disease of the extremity treated with amputation. The majority of these patients eventually developed pulmonary metastases and succumbed to their disease. The introduction of effective chemotherapy has dramatically improved the outcome of patients with localized disease, but has not altered the survival of patients with metastatic disease. Moreover, there has been little, if any, improvement in the outcomes of patients with localized disease since the mid-1980s. This has led to the investigation of other treatment approaches, including immunotherapy. Coincident with the initial development of chemotherapy, there were early attempts at immunotherapy. These met with little success. Subsequent approaches to harnessing the immune system have yielded more encouraging results. This chapter will review these various approaches, highlighting the role that immunotherapy might play in the multi-modality treatment of localized and metastatic osteosarcoma.

Biomarkers in Osteosarcoma

Osteosarcoma is the most common primary tumor of bone and accounts for approximately 19% of all malignant tumors of bone. It is the third most common malignant tumor in teenagers. More than twenty years ago, the advent of a multidisciplinary approach that combined multi-agent chemotherapy and limb-sparing surgery greatly improved the survival rate of patients with osteosarcoma. Unfortunately, since that time, survival rates have not dramatically improved. To date, the most powerful predictors of outcome have remained the ability to detect metastatic disease at diagnosis and the histopathologic response of the tumor to preoperative chemotherapy. Presently, 80% of patients who do not have distant metastases at initial diagnosis will become long-term survivors. Unfortunately, this means that approximately 20% of patients who do not present with metastases at diagnosis will not survive. This group of patients appears to be resistant to current treatment as attempts to intensify therapy after surgery for patients with a poor histopathologic response has not significantly improved survival rates. It is these patients that are in the greatest need of additional clinically relevant markers for prognosis and who can be most helped by molecular analysis. While steady progress has been made in the identification of genetic alterations in osteosarcoma, no individual molecular marker has thus far been demonstrated to have a better prognostic significance in the treatment of osteosarcomas than the current clinical markers. Thus there is clearly a need to employ new comprehensive analysis technologies to develop significantly more informative classification systems and to identify new therapeutic targets.

Oncolytic Semliki forest virus vector as a novel candidate against unresectable osteosarcoma

Oncolytic viruses are a promising tool for treatment of cancer. We studied an oncolytic Semliki Forest virus (SFV) vector, VA7, carrying the enhanced green fluorescent protein gene (EGFP), as a novel virotherapy candidate against unresectable osteosarcoma. The efficiency and characteristics of the VA7-EGFP treatment were compared with a widely studied oncolytic adenovirus, Ad5Delta24, both in vitro and in vivo. VA7-EGFP resulted in more rapid oncolysis and was more efficient at low multiplicities of infection (MOI) when compared with Ad5Delta24 in vitro. Yet, in MG-63 cells, a subpopulation resistant to the VA7-EGFP vector emerged. In subcutaneous human osteosarcoma xenografts in nude mice treatment with either vector reduced tumor size, whereas tumors in control mice expanded quickly. The VA7-EGFP-treated tumors were either completely abolished or regressed to pinpoint size. The efficacy of VA7-EGFP vector was studied also in an orthotopic osteosarcoma nude mouse model characterized by highly aggressive tumor growth. Treatment with oncolytic SFV extended survival of the animals significantly (P < 0.01), yet none of the animals were finally cured. Sera from SFV-treated mice contained neutralizing antibodies, and as nude mice are not able to establish IgG response, the result points out the role of IgM class antibodies in clearance of virus from peripheral tumors. Furthermore, biodistribution analysis at the survival end point verified the presence of virus in some of the brain samples, which is in line with previous studies demonstrating that IgG is required for clearance of SFV from central nervous system.

Non-viral methods for gene transfer towards osteosarcoma therapy

Osteosarcoma, a class of cancer that originates from bone, afflicts mainly young people usually in their teenage years of life. Despite surgery and chemotherapy, the outlook for sufferers is not that positive, with a third of patients with metastatic disease not surviving past the 10-year mark. Like other neoplasms, other forms of therapeutics are being evaluated, and amongst these is gene therapy. This review discusses approaches for gene therapy of osteosarcoma using cationic liposomes and polyethylenimine in vivo. The field is still in its infancy as far as osteosarcoma is concerned and much more needs to be done to test its true potential as a feasible therapeutic modality.

Gene therapy for osteosarcoma: steps towards clinical studies

Gene therapy, an applied form of biotechnology, relies on the delivery of foreign DNA into cells. More than 50% of all reported clinical trials for gene therapy are for cancer, though only a scant number for osteosarcoma. Osteosarcoma is a neoplasm afflicting young adults, who in their prime years of life suffer debilitation if not death. The disease is not entirely curable, even with surgery combined with aggressive chemotherapy. Thus, other forms of therapies are being evaluated, including gene therapy. There exist two major forms of gene transfer: viral and non-viral. This review only covers proof-of-principle work carried out in cancer beyond the cell culture stage, in animals. Drawing from the experiences of gene therapy against other cancers, studies for which have already reached the clinical phase, the review discusses potential pitfalls and solutions to enhance gene therapy for osteosarcoma.

Liposomal muramyl tripeptide phosphatidyl ethanolamine: a safe and effective agent against osteosarcoma pulmonary metastases

Osteosarcoma is the most common form of primary malignant bone tumor. The use of chemotherapy drugs with many side effects, including high-dose methotrexate, doxorubicin, cisplatin and ifosfamide, has greatly improved osteosarcoma survival compared with surgery alone. However, for 20 years, overall survival remained at a plateau of 60-70% in nonmetastatic disease and 20-30% in metastatic osteosarcoma owing to lung metastases. Liposomal muramyl tripeptide phosphatidyl ethanolamine (L-MTP-PE) is a new agent that improves overall osteosarcoma survival (chemotherapy without L-MTP-PE 70% versus with L-MTP-PE 78%; p = 0.03). L-MTP-PE offers additional benefit for osteosarcoma treatment in combination with chemotherapy, particularly ifosfamide-containing regimens. Clinical experience indicates that side effects such as fever are temporary and controlled or prevented with ibuprofen and/or acetoaminophen premedication; severe side effects are rare. Although surgery will remain the main approach for osteosarcoma treatment of lung metastases, L-MTP-PE combined with other modalities, including chemotherapy, appears to be of benefit in these patients as well.

Mucosal priming with PEI/DNA complex and systemic boosting with recombinant TianTan vaccinia stimulate vigorous mucosal and systemic immune responses

An effective vaccine strategy for HIV-1 will probably requires the induction and maintenance of both humoral and cellular immunity. We tested a new prime-boost approach of intranasal priming with 10 microg DNA plasmid in the PEI/DNA complexes and boosting with 10(7)PFU of replicative recombinant TianTan vaccinia virus (rTTV) expressing HIV-1 Gag in BALB/c mice. Intranasal priming with PEI/DNA complexes elicited strikingly stronger HIV-specific T-cell (p=0.0358) and IgA immune responses at mucosal sites of lung (p=0.0445) and vaginal tract (p=0.0469) than intranasal priming with naked DNA, though both are followed by the same rTTV boosting. Furthermore, an intramuscular boosting with rTTV could profoundly enhance both T-cell and antibody immune responses raised by intranasal priming. These results demonstrate that the combination of intranasal priming with PEI/DNA complexes and systemic boosting with rTTV is a preferable regimen for induction of both T-cell and humoral immune responses.

Gene therapy for pulmonary diseases

Gene therapy has not yet met the high expectations of "the early days." However, it is a promising new treatment for lung diseases. Not only single gene disorders such as CF are potential candidates for gene therapy, but also cancer and chronic lung diseases characterized by an imbalance of damaging and protective mechanisms. This review summarizes the recent advances in the development of more efficient gene transfer systems and highlights areas of clinical application of gene therapy.

Liposomal muramyl tripeptide phosphatidyl ethanolamine: ifosfamide-containing chemotherapy in osteosarcoma

Liposomal muramyl tripeptide phosphatidyl ethanolamine (L-MTP-PE) is a synthetic biological investigational agent used for treating osteosarcoma. It has been used in both canine and human osteosarcoma to reduce pulmonary metastases, the most common pattern of treatment failure for sarcomas. L-MTP-PE has been well tolerated using the concept of biological cancer therapy during chemotherapy. The use of L-MTP-PE with ifosfamide is the best studied combination with single agent chemotherapy. This may represent a new treatment choice for osteosarcoma patients receiving ifosfamide. Such patients include those with a poor initial histological response to primary therapy and/or metastatic disease including pulmonary metastases. Reduction of side effects of L-MTP-PE, such as fever and/or flu-like symptoms, with ibuprofen has not reduced efficacy. Since improved symptom control is possible using drug combinations that are especially effective for delayed nausea, outpatient high-dose ifosfamide chemotherapy combined with L-MTP-PE may lead to a safe and effective therapy while maintaining the patients’ quality of life.