E1B-55kD-deleted oncolytic adenovirus armed with canstatin gene yields an enhanced anti-tumor efficacy on pancreatic cancer. Cancer Lett. 2009;285:89-98. [PMID: 19481338 DOI: 10.1016/j.canlet.2009.05.006]

Context Matters: Response Heterogeneity to Collagen-Targeting Approaches in Desmoplastic Cancers

Simple Summary

A common feature of tumor types such as breast cancer, prostate cancer, pancreatic cancer, and soft-tissue sarcoma is the deposition of collagen-rich tissue called desmoplasia. However, efforts to control tumor growth by disrupting desmoplasia, collectively known as “collagen-targeting approaches”, have had mixed and contradictory results, sometimes even within the same cancer type. We believe that this phenomenon may be due—at least partially—to the fact that “collagen” is not a single molecule, but rather a diverse molecular family composed of 28 unique collagen types. Therefore, in this review, we discuss the diversity of collagen molecules in normal and cancer tissue, and explore how collagen heterogeneity relates to the mixed efficacy of collagen-targeting approaches for cancer therapy.

Abstract

The deposition of collagen-rich desmoplastic tissue is a well-documented feature of the solid tumor microenvironment (TME). However, efforts to target the desmoplastic extracellular matrix (ECM) en masse, or collagen molecules more specifically, have been met with mixed and sometimes paradoxical results. In this review, we posit that these discrepancies are due—at least in part—to the incredible diversity of the collagen superfamily. Specifically, whereas studies of “collagen-targeting” approaches frequently refer to “collagen” as a single molecule or relatively homogeneous molecular family, 28 individual collagens have been identified in mammalian tissues, each with a unique structure, supramolecular assembly pattern, tissue distribution, and/or function. Moreover, some collagen species have been shown to exert both pro- and anti-neoplastic effects in the desmoplastic TME, even within the same cancer type. Therefore, herein, we describe the diversity of the collagen family in normal tissues and highlight the context-specific roles of individual collagen molecules in desmoplastic tumors. We further discuss how this heterogeneity relates to the variable efficacy of “collagen-targeting” strategies in this setting and provide guidance for future directions in the field.

Oncolytic virotherapy in hepato-bilio-pancreatic cancer: The key to breaking the log jam?

Traditional therapies have limited efficacy in hepatocellular carcinoma, pancreatic cancer, and biliary tract cancer, especially for advanced and refractory cancers. Through a deeper understanding of antitumor immunity and the tumor microenvironment, novel immunotherapies are becoming available for cancer treatment. Oncolytic virus (OV) therapy is an emerging type of immunotherapy that has demonstrated effective antitumor efficacy in many preclinical studies and clinical studies. Thus, it may represent a potential feasible treatment for hard to treat gastrointestinal (GI) tumors. Here, we summarize the research progress of OV therapy for the treatment of hepato-bilio-pancreatic cancers. In general, most OV therapies exhibits potent, specific oncolysis both in cell lines in vitro and the animal models in vivo. Currently, several clinical trials have suggested that OV therapy may also be effective in patients with refractory hepato-bilio-pancreatic cancer. Multiple strategies such as introducing immunostimulatory genes, modifying virus capsid and combining various other therapeutic modalities have been shown enhanced specific oncolysis and synergistic anti-cancer immune stimulation. Combining OV with other antitumor therapies may become a more effective strategy than using virus alone. Nevertheless, more studies are needed to better understand the mechanisms underlying the therapeutic effects of OV, and to design appropriate dosing and combination strategies.

Oncolytic Viruses for Cancer Therapy: Barriers and Recent Advances

Oncolytic viruses (OVs) are powerful new therapeutic agents in cancer therapy. With the first OV (talimogene laherparepvec [T-vec]) obtaining US Food and Drug Administration approval, interest in OVs has been boosted greatly. Nevertheless, despite extensive research, oncolytic virotherapy has shown limited efficacy against solid tumors. Recent advances in viral retargeting, genetic editing, viral delivery platforms, tracking strategies, OV-based gene therapy, and combination strategies have the potential to broaden the applications of oncolytic virotherapy in oncology. In this review, we present several insights into the limitations and challenges of oncolytic virotherapy, describe the strategies mentioned above, provide a summary of recent preclinical and clinical trials in the field of oncolytic virotherapy, and highlight the need to optimize current strategies to improve clinical outcomes.

A current perspective of canstatin, a fragment of type IV collagen alpha 2 chain

Type IV collagen is a main component of basement membrane extracellular matrix. Canstatin, a non-collagenous C-terminal fragment of type IV collagen α2 chain, was firstly identified as an endogenous anti-angiogenic and anti-tumor factor, which also has an anti-lymphangiogenic effect. Then, canstatin has been widely investigated as a novel target molecule for cancer therapy. The anti-angiogenic effect of canstatin may be also useful for the treatment of ocular neovascularization. Recently, we have demonstrated that canstatin, which is abundantly expressed in the heart tissue, exerts various biological activities in cardiac cells. In rat H9c2 cardiomyoblasts, canstatin inhibits isoproterenol- or hypoxia-induced apoptosis. Canstatin plays an important role in modulating voltage-dependent calcium channel activity in rat cardiomyocytes. Canstatin also regulates various biological functions in rat cardiac fibroblasts and myofibroblasts. The expression of canstatin decreases in the infarcted area after myocardial infarction. This review focuses on a current perspective for the roles of canstatin in tumorigenesis, ocular neovascularization and cardiac pathology.

NIPS, a 3D network-integrated predictor of deleterious protein SAPs, and its application in cancer prognosis

Identifying deleterious mutations remains a challenge in cancer genome sequencing projects, reflecting the vast number of candidate mutations per tumour and the existence of interpatient heterogeneity. Based on a 3D protein interaction network profiled via large-scale cross-linking mass spectrometry, we propose a weighted average formula involving the combination of three types of information into a 'meta-score'. We assume that a single amino acid polymorphism (SAP) may have a deleterious effect if the mutation rarely occurs naturally during evolution, if it inhibits binding between a pair of interacting proteins when located at their interface, or if it plays an important role in a protein interaction (PPI) network. Cross-validation indicated that this new method presents an AUC value of 0.93 and outperforms other widely used tools. The application of this method to the CPTAC colorectal cancer dataset enabled the accurate identification of validated deleterious mutations and yielded insights into their potential pathogenesis. Survival analysis showed that the accumulation of deleterious SAPs is significantly associated with a poor prognosis. The new method provides an alternative method to identifying and ranking deleterious cancer SAPs based on a 3D PPI network and will contribute to the understanding of pathogenesis and the discovery of prognostic biomarkers.

Antitumor activity and inhibitory effects on cancer stem cell-like properties of Adeno-associated virus (AAV) -mediated Bmi-1 interference driven by Bmi-1 promoter for gastric cancer

Bmi-1 is aberrantly activated in various cancers and plays a vital role in maintaining the self-renewal of stem cells. Our previous research revealed that Bmi-1 was overexpressed in gastric cancer (GC) and it's overexpression was an independent negative prognostic factor, suggesting it can be a therapeutic target. The main purpose of this investigation was to explore the antitumor activity of Bmi-1 interference driven by its own promoter (Ad-Bmi-1i) for GC. In this study, we used adenoviral vector to deliver Bmi-1 shRNA driven by its own promoter to treat GC. Our results revealed that Ad-Bmi-1i could selectively silence Bmi-1 in GC cells which overexpress Bmi-1 and suppress the malignant phenotypes and stem-like properties of GC cells in vitro and in vivo. Moreover, direct injection of Ad-Bmi-1i into xenografts suppressed tumor growth and destroyed cancer cells in vivo. Ad-Bmi-1i inhibited the proliferation of GC cells mainly via inducing senescence in vitro, but it suppressed tumor through inducing senescence and apoptosis, and inhibiting angiogenesis in vivo. Bmi-1 knockdown by Ad-Bmi-1i downregulated VEGF via inhibiting AKT activity. These results suggest that Ad-Bmi-1i not only inhibits tumor growth and stem cell-like phenotype by inducing cellular senescence directly, but also has an indirect anti-tumor activity by anti-angiogenesis effects via regulating PTEN/AKT/VEGF pathway. Transfer of gene interference guided by its own promoter by an adeno-associated virus (AAV) vector might be a potent antitumor approach for cancer therapy.

Cancer immunotherapy: moving forward with peptide T cell vaccines

Recent advances in cancer immunology, such as the discovery of immune checkpoint inhibitors, have validated immune cells as potential key players for effective cancer treatment. The efficacy of these therapies seems to be codependent on a tumor-reactive T lymphocyte response. For many years, numerous attempts and strategies in developing vaccines to generate tumor-reactive T cells have yielded poor results in the clinic due to suboptimal immunogenicity and the inability to overcome an immunosuppressive tumor microenvironment. In this review, we summarize past and current advances in T cell vaccines and describe our experience in developing optimized methods for antigen/adjuvant selection and vaccine administration in order to induce powerful anti-tumor responses.

Oncolytic viral therapy for pancreatic cancer

Outcomes of pancreatic adenocarcinoma (PDA) remain dismal despite extensive clinical investigation. Combination chemotherapy provides modest improvements in survival above best supportive care, and immunotherapy has thus far not proven effective. Nevertheless, growing insight into antitumor immunity and the tumor microenvironment has inspired the discovery of novel agents targeting PDA. Oncolytic viruses represent an emerging class of immunotherapeutic agents that have undergone extensive preclinical investigation and warrant further investigation in well-designed clinical trials.

Combining Oncolytic Virotherapy with p53 Tumor Suppressor Gene Therapy

Oncolytic virus (OV) therapy utilizes replication-competent viruses to kill cancer cells, leaving non-malignant cells unharmed. With the first U.S. Food and Drug Administration-approved OV, dozens of clinical trials ongoing, and an abundance of translational research in the field, OV therapy is poised to be one of the leading treatments for cancer. A number of recombinant OVs expressing a transgene for p53 (TP53) or another p53 family member (TP63 or TP73) were engineered with the goal of generating more potent OVs that function synergistically with host immunity and/or other therapies to reduce or eliminate tumor burden. Such transgenes have proven effective at improving OV therapies, and basic research has shown mechanisms of p53-mediated enhancement of OV therapy, provided optimized p53 transgenes, explored drug-OV combinational treatments, and challenged canonical roles for p53 in virus-host interactions and tumor suppression. This review summarizes studies combining p53 gene therapy with replication-competent OV therapy, reviews preclinical and clinical studies with replication-deficient gene therapy vectors expressing p53 transgene, examines how wild-type p53 and p53 modifications affect OV replication and anti-tumor effects of OV therapy, and explores future directions for rational design of OV therapy combined with p53 gene therapy.

The antitumor efficacy of a novel adenovirus-mediated anti-p21Ras single chain fragment variable antibody on human cancers in vitro and in vivo

Activated ras genes are found in a large number of human tumors, and therefore are one of important targets for cancer therapy. This study investigated the antitumor effects of a novel single chain fragment variable antibody (scFv) against ras protein, p21Ras. The anti-p21Ras scFv gene was constructed by phage display library from hybridoma KGHR1, and then subcloned into replication-defective adenovirus vector to obtain recombinant adenovirus KGHV100. Human tumor cell lines with high expression of p21Ras SW480, MDA-MB‑231, OVCAR-3, BEL-7402, as well as tumor cell line with low expression of p21Ras, SKOV3, were employed to investigate antitumor effects in vitro and in vivo. Fluorescence microscopy demonstrated that KGHV100 was able to express intracellularly anti-p21Ras scFv antibody in cultured tumor cells and in transplantation tumor cells. MTT, Transwell, colony formation, and flow cytometry analysis showed that KGHV100 led to significant growth arrest in tumor cells with high p21Ras expression, and induced G0/G1 cell cycle arrest in the studied tumor cell lines. In vivo, KGHV100 significantly inhibited tumor growth following intratumoral injection, and the survival rates of the mice were higher than the control group. These results indicate that the adenovirus-mediated intracellular expression of the novel anti-p21Ras scFv exerted strong antitumoral effects, and may be a potential method for therapy of cancers with p21Ras overexpression.

Conditionally replicating oncolytic adenoviral vector expressing arresten and tumor necrosis factor-related apoptosis-inducing ligand experimentally suppresses lung carcinoma progression

Current methods of treatment for lung carcinoma are ineffective for the majority of patients. Conditionally replicating adenoviruses (CRAds) represent a potential novel treatment for a number of neoplastic diseases, including lung carcinoma. The present study aimed to investigate the synergistic mechanisms underlying the anti-angiogenesis gene, arresten, and the apoptosis-inducing gene, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), in order to evaluate their therapeutic potential in lung cancer. The two genes were expressed by CRAd, which was confirmed using reverse transcription-polymerase chain reaction and western blotting. In vitro analyses demonstrated that CRAd adenoviruses are capable of selectively inhibiting A549 lung cancer cell growth and replication but not in that of healthy cells. In vivo analyses demonstrated that the infection of A549 cell lines using CRAd armed with the two genes (CRAd-arresten-TRAIL) enhanced the tumor inhibition, compared with cells infected with CRAd-arresten, CRAd-TRAIL or CRAd, and with the control group. CRAd-arresten-TRAIL may therefore be useful in the treatment of lung cancer.

Anti-tumor effects of an oncolytic adenovirus expressing hemagglutinin-neuraminidase of Newcastle disease virus in vitro and in vivo

Oncolytic virotherapy has been an attractive drug platform for targeted therapy of cancer over the past few years. Viral vectors can be used to target and lyse cancer cells, but achieving good efficacy and specificity with this treatment approach is a major challenge. Here, we assessed the ability of a novel dual-specific anti-tumor oncolytic adenovirus, expressing the hemagglutinin-neuraminidase (HN) gene from the Newcastle disease virus under the human telomerase reverse transcriptase (hTERT) promoter (Ad-hTERTp-E1a-HN), to inhibit esophageal cancer EC-109 cells in culture and to reduce tumor burden in xenografted BALB/c nude mice. In vitro, infection with Ad-hTERT-E1a-HN could inhibit the growth of EC-109 cells significantly and also protect normal human liver cell line L02 from growth suppression in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Ad-hTERT-E1a-HN also effectively and selectively decreased the sialic acid level on EC-109 cells, but not on L02 cells. Furthermore, Ad-hTERT-E1a-HN was shown to induce the apoptosis pathway via acridine orange and ethidium bromide staining (AO/EB staining), increase reactive oxygen species (ROS), reduce mitochondrial membrane potential and release cytochrome c. In vivo, xenografted BALB/c nude mice were treated via intratumoral or intravenous injections of Ad-hTERT-E1a-HN. Although both treatments showed an obvious suppression in tumor volume, only Ad-hTERT-E1a-HN delivered via intratumoral injection elicited a complete response to treatment. These results reinforced previous findings and highlighted the potential therapeutic application of Ad-hTERT-E1a-HN for treatment of esophageal cancer in clinical trials.

Update on oncolytic viral therapy - targeting angiogenesis

Oncolytic viruses (OVs) have the ability to selectively replicate in and lyse cancer cells. Angiogenesis is an essential requirement for tumor growth. Like OVs, the therapeutic effect of many angiogenesis inhibitors has been limited, leading to the development of more effective approaches to combine antiangiogenic therapy with OVs. Angiogenesis can be targeted either directly by OV infection of vascular endothelial cells, or by arming OVs with antiangiogenic transgenes, which are subsequently expressed locally in the tumor microenvironment. In this review, we describe the development and targeting of OVs, the role of angiogenesis in cancer, and the progress made in arming viruses with antiangiogenic transgenes. Future developments required to optimize this approach are addressed.

Adenovirus vector-mediated Gli1 siRNA induces growth inhibition and apoptosis in human pancreatic cancer with Smo-dependent or Smo-independent Hh pathway activation in vitro and in vivo

Activation of Hedgehog (Hh) signaling pathway is a core molecular mechanism in pancreatic carcinogenesis. However, the inhibition of upstream Hh signals does not inhibit the growth of a subset of pancreatic cancer (PC). This study was to examine the effect of siRNA targeting Gli1, the downstream component of Hh pathway, on PC cells and to provide some insight into the underlying mechanisms. A Gli1siRNA-expressing adenovirus (Ad-U6-Gli1siRNA) was constructed, and its effect on PC cells was investigated in vitro and in vivo. Gli1 was expressed in 83.3% (20/24) PC tissues, whereas no expression was found in normal pancreatic ductal epithelium. Gli1 was expressed in SW1990 and CFPAC cells in which Smo was completely absent, as well as in PaTu8988, Panc-1 and BxPC-3 cells in which Smo was concomitantly present. Ad-U6-Gli1siRNA induced cell growth inhibition, strong G0/G1 cell cycle arrest and apoptosis in all five human PC cell lines. Meanwhile, Ad-U6-Gli1siRNA significantly suppressed the expression of Gli1, Ptch1 and two target genes, Cyclin D2 and Bcl-2, in all five lines. Furthermore, two tumor xenograft nude mice models were established by subcutaneously injecting Smo-positive Panc-1 cells or Smo-negative SW1990 cells. The in vivo experimental results demonstrated that Ad-U6-Gli1siRNA inhibited the growth of both Panc1-derived and SW1990-derived tumors and induced cell apoptosis. Our study indicates that Gli1-targeting siRNA could induce growth inhibition and apoptosis in PC through knockdown of Gli1 and its target genes; and this method may represent a more effective therapeutic strategy for PC with Smo-dependent or Smo-independent Hh pathway activation.

Mounting a strategic offense: fighting tumor vasculature with oncolytic viruses

Blood supply within a tumor drives progression and ultimately allows for metastasis. Many anticancer therapies target tumor vasculature, but their individual effectiveness is limited because they induce indirect cell death. Agents that disrupt nascent and/or established tumor vasculature while simultaneously killing cancer cells would certainly have a greater impact. Oncolytic virotherapy utilizes attenuated viruses that replicate specifically within a tumor. They induce cytotoxicity through a combination of direct cell lysis, antitumor immune stimulation, and recently identified antitumor vascular effects. This review summarizes the novel preclinical and clinical evidence regarding the antitumor vascular effects of oncolytic viruses, which include infection and lysis of tumor endothelial cells, natural or genetically engineered antiangiogenic properties, and combination therapy with clinically approved antivascular agents.

A potential therapeutic strategy for malignant mesothelioma with gene medicine

Malignant mesothelioma, closely linked with occupational asbestos exposure, is relatively rare in the frequency, but the patient numbers are going to increase in the next few decades all over the world. The current treatment modalities are not effective in terms of the overall survival and the quality of life. Mesothelioma mainly develops in the thoracic cavity and infrequently metastasizes to extrapleural organs. A local treatment can thereby be beneficial to the patients, and gene therapy with an intrapleural administration of vectors is one of the potential therapeutics. Preclinical studies demonstrated the efficacy of gene medicine for mesothelioma, and clinical trials with adenovirus vectors showed the safety of an intrapleural injection and a possible involvement of antitumor immune responses. Nevertheless, low transduction efficiency remains the main hurdle that hinders further clinical applications. Moreover, rapid generation of antivector antibody also inhibits transgene expressions. In this paper, we review the current status of preclinical and clinical gene therapy for malignant mesothelioma and discuss potential clinical directions of gene medicine in terms of a combinatory use with anticancer agents and with immunotherapy.

Treatment of pancreatic cancer using an oncolytic virus harboring the lipocalin-2 gene

BACKGROUND

The 5-year survival rate for patients with pancreatic cancer is <5%, and it is always resistant to the current chemoradiotherapy. Therefore, new, effective agents for the treatment of pancreatic cancer are urgently needed. The promising strategy of cancer-targeting gene virotherapy (CTGVT) has demonstrated great anticancer potential. The objective of the current study was to determine whether 1 CTGVT approach, oncolytic virus (OV)-harboring lipocalin-2, is capable of treating pancreatic cancer.

METHODS

Tissue microarrays were constructed to detect the expression of lipocalin-2 in 60 specimens of pancreatic adenocarcinoma. The clinical significance of lipocalin-2 was investigated in an analysis of correlations between lipocalin-2 expression and matched clinical characteristics. A lipocalin-2-expressing OV, ZD55-lipocalin-2, was constructed by deleting the adenoviral protein E1B55kD. The antitumor efficacy and mechanisms of the OV were investigated in pancreatic cancer cells with v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations in vitro and in vivo.

RESULTS

Lipocalin-2 expression was correlated with a good prognosis in patients with pancreatic adenocarcinoma. ZD55-lipocalin-2 dramatically inhibited the growth of pancreatic cancer in vitro and in vivo by inducing cytolysis and caspase-dependent apoptosis.

CONCLUSIONS

Higher lipocalin-2 expression predicted a better prognosis in patients with pancreatic cancer. The results indicated that ZD55-lipocalin-2, which specifically expressed higher levels of lipocalin-2 in tumor cells, may serve as a potent anticancer drug for pancreatic cancer therapy, especially for patients who have pancreatic adenocarcinoma with KRAS mutations.

Vesicular stomatitis virus as an oncolytic agent against pancreatic ductal adenocarcinoma

Vesicular stomatitis virus (VSV) is a promising oncolytic agent against a variety of cancers. However, it has never been tested in any pancreatic cancer model. Pancreatic ductal adenocarcinoma (PDA) is the most common and aggressive form of pancreatic cancer. In this study, the oncolytic potentials of several VSV variants were analyzed in a panel of 13 clinically relevant human PDA cell lines and compared to conditionally replicative adenoviruses (CRAds), Sendai virus and respiratory syncytial virus. VSV variants showed oncolytic abilities superior to those of other viruses, and some cell lines that exhibited resistance to other viruses were successfully killed by VSV. However, PDA cells were highly heterogeneous in their susceptibility to virus-induced oncolysis, and several cell lines were resistant to all tested viruses. Resistant cells showed low levels of very early VSV RNA synthesis, indicating possible defects at initial stages of infection. In addition, unlike permissive PDA cell lines, most of the resistant cell lines were able to both produce and respond to interferon, suggesting that intact type I interferon responses contributed to their resistance phenotype. Four cell lines that varied in their permissiveness to VSV-ΔM51 and CRAd dl1520 were tested in mice, and the in vivo results closely mimicked those in vitro. While our results demonstrate that VSV is a promising oncolytic agent against PDA, further studies are needed to better understand the molecular mechanisms of resistance of some PDAs to oncolytic virotherapy.

Proteolytically Derived Endogenous Angioinhibitors Originating from the Extracellular Matrix

Angiogenesis, a neovascularization process induced from the existing parent blood vessels, is a prerequisite for many physiological and pathological conditions. Under physiological conditions it is regulated by a balance between endogenous angioinhibitors and angioactivators, and an imbalance between them would lead to pathological conditions such as cancer, age-related macular degeneration (AMD), diabetic retinopathy, cardiovascular diseases, etc. Several proteolytically generated endogenous molecules have been identified which exhibit angioinhibition and/or antitumor activities. These angioinhibitors interact with endothelial and tumor cells by binding to distinct integrins and initiate many of their intracellular signaling mechanisms regulating the cell survival and or apoptotic pathways. The present review will focus on the extracellular matrix derived angioinhibitors, and their mechanisms of actions that point to the clinical significance and therapeutic implications.

Inhibitory effect of Survivin promoter-regulated oncolytic adenovirus carrying P53 gene against gallbladder cancer

Gene therapy has become an important strategy for treatment of malignancies, but problems remains concerning the low gene transferring efficiency, poor transgene expression and limited targeting specific tumors, which have greatly hampered the clinical application of tumor gene therapy. Gallbladder cancer is characterized by rapid progress, poor prognosis, and aberrantly high expression of Survivin. In the present study, we used a human tumor-specific Survivin promoter-regulated oncolytic adenovirus vector carrying P53 gene, whose anti-cancer effect has been widely confirmed, to construct a wide spectrum, specific, safe, effective gene-viral therapy system, AdSurp-P53. Examining expression of enhanced green fluorecent protein (EGFP), E1A and the target gene P53 in the oncolytic adenovirus system validated that Survivin promoter-regulated oncolytic adenovirus had high proliferation activity and high P53 expression in Survivin-positive gallbladder cancer cells. Our in vitro cytotoxicity experiment demonstrated that AdSurp-P53 possessed a stronger cytotoxic effect against gallbladder cancer cells and hepatic cancer cells. The survival rate of EH-GB1 cells was lower than 40% after infection of AdSurp-P53 at multiplicity of infection (MOI) = 1 pfu/cell, while the rate was higher than 90% after infection of Ad-P53 at the same MOI, demonstrating that AdSurp-P53 has a potent cytotoxicity against EH-GB1 cells. The tumor growth was greatly inhibited in nude mice bearing EH-GB1 xenografts when the total dose of AdSurp-P53 was 1 × 10(9) pfu, and terminal dUTP nick end-labeling (TUNEL) revealed that the apoptotic rate of cancer cells was (33.4 ± 8.4)%. This oncolytic adenovirus system overcomes the long-standing shortcomings of gene therapy: poor transgene expression and targeting of only specific tumors, with its therapeutic effect better than the traditional Ad-P53 therapy regimen already on market; our system might be used for patients with advanced gallbladder cancer and other cancers, who are not sensitive to chemotherapy, radiotherapy, or who lost their chance for surgical treatment.

Recent advances in immunotherapy for human pancreatic cancer

Pancreatic cancer is one of the common highly malignant digestive system tumors. It is associated with a high mortality rate because of early metastasis, low resection rate and poor chemoradiotherapy response. Advances in immunology, such as tumor antigen, immunological surveillance, immunological evasion, immunological tolerance, T cell signal transduction, regulation of cytokines and regulatory DCs, down-regulation of co-stimulatory molecules, and tumor microenvironment, have enriched our knowledge and promoted the development of immunotherapy for pancreatic cancer. In this paper, we will review the recent advances in immunotherapy for pancreatic cancer.

Advances in viral-vector systemic cytokine gene therapy against cancer

Current strategies for cancer gene therapy consist mainly of direct inhibition of tumor cell growth and activation of systemic host defense mechanisms. Cytokine gene-transduced tumor cells have been used as vaccines in clinical trials, which have shown good safety profiles and some local responses but substantial lack of systemic efficacy. Cytokines should be directed at the level of gene selection and delivery, in order to identify the optimal cytokine and achieve efficient and durable cytokine expression at the level of improving immune stimulation. In this review, we will summarize the current achievements of cytokine gene therapy, especially viral-vector, and their applications in cancer treatment. Additionally, we will also discuss and propose future perspectives about cancer gene therapy.

Oncolytic Viruses for Cancer Therapy: Overcoming the Obstacles

Targeted therapy of cancer using oncolytic viruses has generated much interest over the past few years in the light of the limited efficacy and side effects of standard cancer therapeutics for advanced disease. In 2006, the world witnessed the first government-approved oncolytic virus for the treatment of head and neck cancer. It has been known for many years that viruses have the ability to replicate in and lyse cancer cells. Although encouraging results have been demonstrated in vitro and in animal models, most oncolytic viruses have failed to impress in the clinical setting. The explanation is multifactorial, determined by the complex interactions between the tumor and its microenvironment, the virus, and the host immune response. This review focuses on discussion of the obstacles that oncolytic virotherapy faces and recent advances made to overcome them, with particular reference to adenoviruses.