Adenovirus-mediated p53 gene transfer in advanced non-small-cell lung cancer

Twenty years of Gendicine® rAd-p53 cancer gene therapy: The first-in-class human cancer gene therapy in the era of personalized oncology

Genetic mutations in TP53 contribute to human malignancies through various means. To date, there have been a variety of therapeutic strategies targeting p53, including gene therapy to restore normal p53 function, mutant p53 rescue, inhibiting the MDM2-p53 interaction, p53-based vaccines, and a number of other approaches. This review focuses on the functions of TP53 and discusses the aberrant roles of mutant p53 in various types of cancer. Recombinant human p53 adenovirus, trademarked as Gendicine, which is the first anti-tumor gene therapy drug, has made tremendous progress in cancer gene therapy. We herein discuss the biological mechanisms by which Gendicine exerts its effects and describe the clinical responses reported in clinical trials. Notably, the clinical studies suggest that the combination of Gendicine with chemotherapy and/or radiotherapy may produce more pronounced efficacy in slowing tumor growth and progression than gene therapy/chemotherapy alone. Finally, we summarize the methods of administration of recombinant human p53 adenovirus for different cancer types to provide a reference for future clinical trials.

Oncolytic Viruses and Cancer Immunotherapy

PURPOSE OF REVIEW

Oncolytic viruses (OVs) exert their antitumor effect through selective killing of cancer cells and induction of host anti-tumor immunity. This review aims to summarize the recent and current trials with OVs for the treatment of lung cancer.

RECENT FINDINGS

Several OVs have been developed for the treatment of lung cancer including adenovirus, coxsackievirus B3, reovirus, and vaccinia virus and trials have demonstrated a safe toxicity profile. Early-phase trials in lung cancer with OVs have reported antiviral immune responses and evidence of clinical benefit. However, clinical efficacy of OVs in lung cancer either as monotherapy or in combination with chemotherapy has not been confirmed in larger phase II or III trials. Development of OVs in lung cancer has been limited by difficulty in administering OVs in the tumor directly as well as achieving adequate viral load at all tumor sites with systemically administered OVs. Developing novel combinations with OVs, especially checkpoint inhibitors and other immunotherapeutics, may be a strategy to address the limited success seen thus far. Integrating appropriate biomarker studies and meaningful endpoints in future clinical trials will be imperative. Using novel viral delivery systems in addition to increasing tumor specificity through improved genetic modifications in the OVs are other strategies to improve efficacy.

Mechanism of apoptosis activation by Curcumin rescued mutant p53Y220C in human pancreatic cancer

The mutant p53Y220C (mutp53Y220C) is frequently observed in numerous tumors, including pancreatic cancer. The mutation creates a crevice in the DNA binding core domain and makes p53 a thermally unstable non-functional protein that assists tumor progression and confers resistance to chemotherapeutic drugs. Restoring mutp53 function to its wild type by selectively targeting this crevice with small molecules is a pivotal strategy to promote apoptosis. In this study, we have shown through different biophysical and cell-based studies that curcumin binds and rescues mutp53Y220C to an active wild-type conformation and restores its apoptotic transcription function in BxPC-3-pancreatic cancer cells. In addition, the curcumin-rescued-p53Y220C (CRp53) showed significant hyperphosphorylation at Ser15, Ser20, and acetylation at Lys382 with an 8-fold increase in transcription activity in the BxPC-3 cell lines. We also observed that the active CRp53 escapes Mdm2-mediated proteasomal degradation and the majority of the proteins were localized inside the nucleus with an increased half-life and transcription restoration compared to untreated BxPC-3 cells. By label-free proteomics analysis, we observed that upon curcumin treatment almost 227 proteins were dysregulated with the majority of them being transcriptional targets of p53. Based on our studies, it reflects that apoptosis in pancreatic cancer cells is mediated by curcumin-rescued mutant p53Y220C.

Molecular Targeting of the Most Functionally Complex Gene in Precision Oncology: p53

While chemotherapy is a key treatment strategy for many solid tumors, it is rarely curative, and most tumor cells eventually become resistant. Because of this, there is an unmet need to develop systemic treatments that capitalize on the unique mutational landscape of each patient's tumor. The most frequently mutated protein in cancer, p53, has a role in nearly all cancer subtypes and tumorigenesis stages and therefore is one of the most promising molecular targets for cancer treatment. Unfortunately, drugs targeting p53 have seen little clinical success despite promising preclinical data. Most of these drug compounds target specific aspects of p53 inactivation, such as through inhibiting negative regulation by the mouse double minute (MDM) family of proteins. These treatment strategies fail to address cancer cells' adaptation mechanisms and ignore the impact that p53 loss has on the entire p53 network. However, recent gene therapy successes show that targeting the p53 network and cellular dysfunction caused by p53 inactivation is now possible and may soon translate into successful clinical responses. In this review, we discuss p53 signaling complexities in cancer that have hindered the development and use of p53-targeted drugs. We also describe several current therapeutics reporting promising preclinical and clinical results.

Novel Insights into the Therapeutic Potential of Lung-Targeted Gene Transfer in the Most Common Respiratory Diseases

Over the past decades, a better understanding of the genetic and molecular alterations underlying several respiratory diseases has encouraged the development of new therapeutic strategies. Gene therapy offers new therapeutic alternatives for inherited and acquired diseases by delivering exogenous genetic materials into cells or tissues to restore physiological protein expression and/or activity. In this review, we review (1) different types of viral and non-viral vectors as well as gene-editing techniques; and (2) the application of gene therapy for the treatment of respiratory diseases and disorders, including pulmonary arterial hypertension, idiopathic pulmonary fibrosis, cystic fibrosis, asthma, alpha-1 antitrypsin deficiency, chronic obstructive pulmonary disease, non-small-cell lung cancer, and COVID-19. Further, we also provide specific examples of lung-targeted therapies and discuss the major limitations of gene therapy.

Bronchoscopic intratumoural therapies for non-small cell lung cancer

The past decade has brought remarkable improvements in the treatment of non-small cell lung cancer (NSCLC) with novel therapies, such as immune checkpoint inhibitors, although response rates remain suboptimal. Direct intratumoural injection of therapeutic agents via bronchoscopic approaches poses the unique ability to directly target the tumour microenvironment and offers several theoretical advantages over systemic delivery including decreased toxicity. Increases in understanding of the tumour microenvironment and cancer immunology have identified many potential options for intratumoural therapy, especially combination immunotherapies. Herein, we review advances in the development of novel bronchoscopic treatments for NSCLC over the past decade with a focus on the potential of intratumoural immunotherapy alone or in combination with systemic treatments.

Non-small-cell lung cancer homing peptide-labeled dendrimers selectively transfect lung cancer cells

AIM

Lung cancer gene therapies require reagents to selectively transfect lung tumors after systemic administration.

MATERIALS & METHODS

We created a reagent called NSCLC-NP by attaching a peptide with binding affinity for lung cancer to polyamidoamine dendrimers. The positively charged dendrimers electrostatically bind negatively charged nucleic acids, inhibit endogenous nucleases and transfect cells targeted by the attached peptide.

RESULTS

In vitro, NSCLC-NP complexed to DNA plasmids bound and transfected three human lung cancer cell lines producing protein expression of the plasmid's gene. In vivo, systemically administered NSCLC-NP selectively transfected lung cancer cells growing in RAG1KO mice.

CONCLUSION

The capability of NSCLC-NP to selectively transfect lung cancer allows its future use as a vehicle to implement human lung cancer gene therapy strategies.

Hope and challenge: Precision medicine in bladder cancer

Bladder cancer (BC) is a complex disease and could be classified into nonmuscle‐invasive BC (NMIBC) or muscle‐invasive BC (MIBC) subtypes according to the distinct genetic background and clinical prognosis. Until now, the golden standard and confirmed diagnosis of BC is cystoscopy and the major problems of BC are the high rate of recurrence and high costs in the clinic. Recent molecular and genetic studies have provided perspectives on the novel biomarkers and potential therapeutic targets of BC. In this article, we provided an overview of the traditional diagnostic approaches of BC, and introduced some new imaging, endoscopic, and immunological diagnostic technology in the accurate diagnosis of BC. Meanwhile, the minimally invasive precision treatment technique, immunotherapy, chemotherapy, gene therapy, and targeted therapy of BC were also included. Here, we will overview the diagnosis and therapy methods of BC used in clinical practice, focusing on their specificity, efficiency, and safety. On the basis of the discussion of the benefits of precision medicine in BC, we will also discuss the challenges and limitations facing the non‐invasive methods of diagnosis and precision therapy of BC. The molecularly targeted and immunotherapeutic approaches, and gene therapy methods to BC treatment improved the prognosis and overall survival of BC patients.

Treatment of Uterine Sarcoma with rAd-p53 (Gendicine) Followed by Chemotherapy: Clinical Study of TP53 Gene Therapy

This study evaluated the efficacy of rAd-p53 (Gendicine^®) followed by chemotherapy for the treatment of uterine sarcoma. Twelve cases of uterine sarcoma treated at Shengjing Hospital were retrospectively analyzed. Among the 12 patients, one had primary cancer, and 11 had recurrent cancer. For the recurrent cases, the interval between the first operation and diagnosis of recurrence, or progression-free survival time 1 (PFS1), was 1-18 months (median 3 months). All patients were treated with local application of rAd-p53 followed by chemotherapy (local injection of bleomycin and i.v. infusion of cisplatin, epirubicin, and isocyclophosphamide). Efficacy was evaluated, and the rates of complete remission (CR) and partial remission (PR) were calculated. During follow-up, PFS time 2 (PFS2) after the baseline period and overall survival (OS) time after the baseline period of rAd-p53 treatment data were obtained. The treatment resulted in one CR, seven PR, three with stable disease (SD), and one with progressive disease (PD). The remission rate (CR + PR) was 66.7%, and the responsive (CR + PR + SD) rate was 91.7%. PFS2 ranged from 2 to 62 months, with a median of 13 months, which is 10 months longer than that of PFS1; this difference was statistically significant (p = 0.0038). The OS time ranged from 6 to 62 months, with a median of 24 months. Following the combined treatment, four of the patients underwent a second debulking surgery. Of the two patients with liver metastases, one had CR of liver foci, and one had PR. Up to the follow-up date of the two patients who survived, one was tumor-free for 60 months. The PFS2 for the other patient was 39 months. This patient survived with tumor for 53 months with slow disease progression. The remaining 10 patients died. Local application of rAd-p53 combined with local injection of bleomycin and intravenous infusion of cisplatin, epirubicin and isocyclophosphamide was effective for treatment of uterine sarcoma, especially for patients with liver metastases. For patients with uterine sarcoma who do not have the opportunity for surgery, this regimen can be used as a new adjuvant therapy to obtain a surgical opportunity that allows further debulking of the tumor mass.

A MicroRNA Derived from Adenovirus Virus-Associated RNAII Promotes Virus Infection via Posttranscriptional Gene Silencing

The adenovirus (Ad) serotype 5 genome encodes two noncoding small RNAs (virus-associated RNAs I and II [VA-RNAI and -II]), which are approximately 160-nucleotide (nt) RNAs transcribed by RNA polymerase III. It is well known that VA-RNAI supports Ad infection via the inhibition of double-stranded RNA-dependent protein kinase (PKR), which recognizes double-stranded RNA and acts as an antiviral system. Recent studies revealed that VA-RNAs are processed into VA-RNA-derived microRNAs (miRNAs) (mivaRNAI and -II); however, we and another group recently demonstrated that mivaRNAI does not promote Ad replication. On the other hand, the roles of VA-RNAII and mivaRNAII in Ad replication have remained to be clarified. In this study, we demonstrated mivaRNAII-mediated promotion of Ad replication. Transfection with chemically synthesized 3'-mivaRNAII-138, one of the most abundant forms of mivaRNAII, significantly enhanced Ad replication, while the other species of mivaRNAII did not. We identified 8 putative target genes of 3'-mivaRNAII-138 by microarray analysis and in silico analysis. Among the 8 candidates, knockdown of the cullin 4A (CUL4A) gene, which encodes a component of the ubiquitin ligase complex, most significantly enhanced Ad replication. CUL4A expression was significantly suppressed by 3'-mivaRNAII-138 via posttranscriptional gene silencing, indicating that CUL4A is a target gene of 3'-mivaRNAII-138 and mivaRNAII functions as a viral miRNA promoting Ad infection. It has been reported that CUL4A is involved in degradation of c-Jun, which acts as a transcription factor in the Jun-N-terminal kinase (JNK) signaling cascade. Treatment with JNK inhibitors dramatically suppressed Ad replication, suggesting that mivaRNAII-mediated downregulation of CUL4A enhanced JNK signaling and thereby promoted Ad infection.IMPORTANCE Several types of viruses encode viral miRNAs which regulate host and/or viral gene expression via posttranscriptional gene silencing, leading to efficient viral infection. Adenovirus (Ad) expresses miRNAs derived from VA-RNAs (mivaRNAI and -II); however, recent studies have revealed that processing of VA-RNAI into mivaRNAI inhibits Ad replication. Conversely, we demonstrate here that mivaRNAII significantly promotes Ad replication and that mivaRNAII-mediated suppression of CUL4A expression via posttranscriptional gene silencing induces accumulation of c-Jun, leading to promotion of Ad infection. These results exhibited the significance of VA-RNAII for supporting Ad infection through a mechanism complementary to that of VA-RNAI. These observations could provide important clues toward a new perspective on host-virus interaction. Moreover, Ad is widely used as a basic framework for viral vectors and oncolytic viruses. Our findings will help to regulate Ad infection and will promote the development of novel Ad vectors and oncolytic Ad.

Therapeutic bronchoscopy in the era of genotype directed lung cancer management

Lung cancer is the leading cause of cancer related deaths. Non-small cell lung cancer (NSCLC) accounts for ~85% of lung cancers. Our understanding of driver mutations and genotype directed therapy has revolutionized the management of advanced NSCLC. Commonly described mutations include mutations in epidermal growth factor (EGFR) & BRAF and translocations in anaplastic lymphoma kinase (ALK) & rat osteosarcoma (ROS1). Drugs directed against these translocations have significantly improved progression free survival individually and have shown a survival benefit when studied in the Lung Cancer Mutation Consortium (median survival 3.5 vs. 2.4 years compared to standard therapy). In a related yet parallel universe, the number of bronchoscopic ablative modalities available for management of cancer related airway obstruction have increased exponentially over the past decade. A wealth of literature has given us a better understanding of the technical aspects, benefits and risks associated with these procedures. While they all show benefits in terms of relieving airway obstruction, symptom control, quality of life and lung function testing, their complication rates vary based on the modality. The overall complication rate was ~4% in the AQuIRE registry. Bronchoscopic therapeutic modalities include rigid bronchoscopy with mechanical debulking, laser, thermo-coagulation [electrocautery & argon plasma coagulation (APC)], cryotherapy, endobronchial brachytherapy (EBT), photodynamic therapy (PDT), intratumoral chemotherapy (ITC) and transbronchial needle injection (TBNI) of chemotherapy. Intuitively, one would assume that the science of driver mutations would crisscross with the science of bronchoscopic ablation as they overlap in the same patient population. Sadly, this is not the case and there is a paucity of literature looking at these fields together. This results in several unanswered questions about the interplay between these two therapies.

Targeting p53 as a promising therapeutic option for cancer by re-activating the wt or mutant p53’s tumor suppression

p53 protein, a product of the TP53 tumor suppressor gene, controls the cellular genome’s integrity and is an important regulator of cell cycling, proliferation, apoptosis and metabolism. Mutations of TP53 or inactivation of its gene product are among the first events initiating malignant transformation. The consequent loss of control over the cell cycle, resulting in accelerated cell proliferation and facilitating metabolic reprogramming, gives the initiated (premalignant) cells numerous advantages over healthy cells. Interestingly, p53 status is not only an important marker in cancer diagnosis; it has also become a promising target of personalized therapy. Depending on the TP53 status different therapeutic options have been developed. (Re)-activation of p53 functionality in cancer cells offers promising new alternatives to existing oncological therapies.

The curcumin analog HO-3867 selectively kills cancer cells by converting mutant p53 protein to transcriptionally active wildtype p53

p53 is an important tumor-suppressor protein that is mutated in more than 50% of cancers. Strategies for restoring normal p53 function are complicated by the oncogenic properties of mutant p53 and have not met with clinical success. To counteract mutant p53 activity, a variety of drugs with the potential to reconvert mutant p53 to an active wildtype form have been developed. However, these drugs are associated with various negative effects such as cellular toxicity, nonspecific binding to other proteins, and inability to induce a wildtype p53 response in cancer tissue. Here, we report on the effects of a curcumin analog, HO-3867, on p53 activity in cancer cells from different origins. We found that HO-3867 covalently binds to mutant p53, initiates a wildtype p53-like anticancer genetic response, is exclusively cytotoxic toward cancer cells, and exhibits high anticancer efficacy in tumor models. In conclusion, HO-3867 is a p53 mutant-reactivating drug with high clinical anticancer potential.

Gene Therapy for Lung Cancer

Gene therapy was originally conceived to treat monogenic diseases. The replacement of a defective gene with a functional gene can theoretically cure the disease. In cancer, multiple genetic defects are present and the molecular profile changes during the course of the disease, making the replacement of all defective genes impossible. To overcome these difficulties, various gene therapy strategies have been adopted, including immune stimulation, transfer of suicide genes, inhibition of driver oncogenes, replacement of tumor-suppressor genes that could mediate apoptosis or anti-angiogenesis, and transfer of genes that enhance conventional treatments such as radiotherapy and chemotherapy. Some of these strategies have been tested successfully in non-small-cell lung cancer patients and the results of laboratory studies and clinical trials are reviewed herein.

Genetic Modification of the Lung Directed Toward Treatment of Human Disease

Genetic modification therapy is a promising therapeutic strategy for many diseases of the lung intractable to other treatments. Lung gene therapy has been the subject of numerous preclinical animal experiments and human clinical trials, for targets including genetic diseases such as cystic fibrosis and α1-antitrypsin deficiency, complex disorders such as asthma, allergy, and lung cancer, infections such as respiratory syncytial virus (RSV) and Pseudomonas, as well as pulmonary arterial hypertension, transplant rejection, and lung injury. A variety of viral and non-viral vectors have been employed to overcome the many physical barriers to gene transfer imposed by lung anatomy and natural defenses. Beyond the treatment of lung diseases, the lung has the potential to be used as a metabolic factory for generating proteins for delivery to the circulation for treatment of systemic diseases. Although much has been learned through a myriad of experiments about the development of genetic modification of the lung, more work is still needed to improve the delivery vehicles and to overcome challenges such as entry barriers, persistent expression, specific cell targeting, and circumventing host anti-vector responses.

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.

Presage of oncolytic virotherapy for oral cancer with herpes simplex virus

A virus is a pathogenic organism that causes a number of infectious diseases in humans. The oral cavity is the site at which viruses enter and are excreted from the human body. Herpes simplex virus type 1 (HSV-1) produces the primary infectious disease, gingivostomatitis, and recurrent disease, labial herpes. HSV-1 is one of the most extensively investigated viruses used for cancer therapy. In principle, HSV-1 infects epithelial cells and neuronal cells and exhibits cytotoxicity due to its cytopathic effects on these cells. If the replication of the virus occurs in tumor cells, but not normal cells, the virus may be used as an antitumor agent. Therefore, HSV-1 genes have been modified by genetic engineering, and in vitro and in vivo studies with the oncolytic virus have demonstrated its efficiency against head and neck cancer including oral cancer. The oncolytic abilities of other viruses such as adenovirus and reovirus have also been demonstrated. In clinical trials, HSV-1 is the top runner and is now available for the treatment of patients with advanced melanoma. Thus, melanoma in the oral cavity is the target of oncolytic HSV-1. Oncolytic virotherapy is a hopeful and realistic modality for the treatment of oral cancer.

The 'Pushmi-Pullyu' of DNA REPAIR: Clinical Synthetic Lethality

Maintenance of genomic integrity is critical for adaptive survival in the face of endogenous and exogenous environmental stress. The loss of stability and fidelity in the genome caused by cancer and cancer treatment provides therapeutic opportunities to leverage the critical balance between DNA injury and repair. Blocking repair and pushing damaged DNA through the cell cycle using therapeutic inhibitors exemplify the 'pushmi-pullyu' effect of disrupted DNA repair. DNA repair inhibitors (DNARi) can be separated into five biofunctional categories: sensors, mediators, transducers, effectors, and collaborators that recognize DNA damage, propagate injury DNA messages, regulate cell cycle checkpoints, and alter the microenvironment. The result is cancer therapeutics that takes advantage of clinical synthetic lethality, resulting in selective tumor cell kill. Here, we review recent considerations related to DNA repair and new DNARi agents and organize those findings to address future directions and clinical opportunities.

Autoregulated expression of p53 from an adenoviral vector confers superior tumor inhibition in a model of prostate carcinoma gene therapy

Alternative treatments for cancer using gene therapy approaches have shown promising results and some have even reached the marketplace. Even so, additional improvements are needed, such as employing a strategically chosen promoter to drive expression of the transgene in the target cell. Previously, we described viral vectors where high-level transgene expression was achieved using a p53-responsive promoter. Here we present an adenoviral vector (AdPGp53) where p53 is employed to regulate its own expression and which outperforms a traditional vector when tested in a model of gene therapy for prostate cancer. The functionality of AdPGp53 and AdCMVp53 were compared in human prostate carcinoma cell lines. AdPGp53 conferred greatly enhanced levels of p53 protein and induction of the p53 target gene, p21, as well as superior cell killing by a mechanism consistent with apoptosis. DU145 cells were susceptible to induction of death with AdPGp53, yet PC3 cells were quite resistant. Though AdCMVp53 was shown to be reliable, extremely high-level expression of p53 offered by AdPGp53 was necessary for tumor suppressor activity in PC3 and DU145. In situ gene therapy experiments revealed tumor inhibition and increased overall survival in response to AdPGp53, but not AdCMVp53. Upon histologic examination, only AdPGp53 treatment was correlated with the detection of both p53 and TUNEL-positive cells. This study points to the importance of improved vector performance for gene therapy of prostate cancer.

Rejection of adenovirus infection is independent of coxsackie and adenovirus receptor expression in cisplatin-resistant human lung cancer cells

The adenovirus vector-based cancer gene therapy is controversial. Low transduction efficacy is believed to be one of the main barriers for the decreased expression of coxsackie and adenovirus receptor (CAR) on tumor cells. However, the expression of CAR on primary tumor tissue and tumor tissue survived from treatment has still been not extensively studied. The present study analyzed the adenovirus infection rates and CAR expression in human lung adenocarcinoma cell line A549 and its cisplatin-resistant subline A549/DDP. The results showed that although the CAR expression in A549 and A549/DDP was not different, compared with the A549, A549/DDP appeared obviously to reject adenovirus infection. Moreover, we modified CAR expression in the two cell lines with proteasome inhibitor MG-132 and histone deacetylase inhibitor trichostatin A (TSA), and analyzed the adenovirus infection rates after modifying agent treatments. Both TSA and MG-132 pretreatments could increase the CAR expression in the two cell lines, but the drug pretreatments could only make A549 cells more susceptible to adenovirus infectivity.

The use of the NIS reporter gene for optimizing oncolytic virotherapy

Introduction: Oncolytic viruses are experimental cancer therapies being translated to the clinic. They are unique in their ability to amplify within the body, therefore requiring careful monitoring of viral replication and biodistribution. Traditional monitoring strategies fail to recapitulate the dynamic nature of oncolytic virotherapy. Consequently, clinically relevant, noninvasive, high resolution strategies are needed to effectively track virotherapy in real time.

Areas covered: The expression of the sodium iodide symporter (NIS) reporter gene is tightly coupled to viral genome replication and mediates radioisotope concentration, allowing noninvasive molecular nuclear imaging of active viral infection with high resolution. This provides insight into replication kinetics, biodistribution, the impact of vector design, administration, and dosing on therapeutic outcomes, and highlights the heterogeneity of spatial distribution and temporal evolution of infection. NIS-mediated imaging in clinical trials confirms the feasibility of this technology to noninvasively and longitudinally observe oncolytic virus infection, replication, and distribution.

Expert opinion: NIS-mediated imaging provides detailed functional and molecular information on the evolution of oncolytic virus infection in living animals. The use of NIS reporter gene imaging has rapidly advanced to provide unparalleled insight into the spatial and temporal context of oncolytic infection which will be integral to optimization of oncolytic treatment strategies.

p53 as a target for the treatment of cancer

TP53 (p53) is the most frequently mutated gene in cancer, being altered in approximately 50% of human malignancies. In most, if not all, cancers lacking mutation, wild-type (WT) p53 is inactivated by interaction with cellular (MDM2/MDM4) or viral proteins, leading to its degradation. Because of its near universal alteration in cancer, p53 is an attractive target for the development of new targeted therapies for this disease. However, until recently, p53 was widely regarded as ‘‘undruggable’’. This situation has now changed, as several compounds have become available that can restore wild-type properties to mutant p53 (e.g., PRIMA-1 and PRIMA-1MET). Other compounds are available that prevent the binding of MDM2/MDM4 to WT p53, thereby blocking its degradation (e.g., nutlins). Anti-mutant p53 compounds are potentially most useful in cancers with a high prevalence of p53 mutations. These include difficult-totreat tumors such as high grade serous ovarian cancer, triple-negative breast cancer and squamous lung cancer. MDM2/4 antagonists, on the other hand, are likely to be efficacious in malignancies in which MDM2 or MDM4 is overexpressed such as sarcomas, neuroblastomas and specific childhood leukemias. Presently, early clinical trials are ongoing evaluating the anti-mutant p53 agent, PRIMA-1MET, and specific MDM2–p53 nutlin antagonists.

Ad-REIC Gene Therapy: Promising Results in a Patient with Metastatic CRPC Following Chemotherapy

A 63-year-old man with metastatic castration-resistant prostate cancer (CRPC) was successfully treated for two years with in situ gene therapy using an adenovirus vector carrying the human REIC/Dkk-3 gene (Ad-REIC), following chemotherapy. Ad-REIC mediates simultaneous induction of cancer-selective apoptosis and augmentation of antitumor immunity, and a Phase I/IIa clinical study on Ad-REIC has been conducted at Okayama University Hospital since January 2011. At the time of enrollment in December 2012, the patient presented with rapid progression of lymph node (LN) metastases. Two scheduled Ad-REIC injections and 10 additional Ad-REIC injections into metastatic pelvic and para-aortic LNs under CT guidance, with an average four weeks' interval, exhibited the potent direct and indirect effects of Ad-REIC as a therapeutic cancer vaccine. During the next 12 months, three additional injections into para-aortic LNs showing regrowth achieved adequate control of all metastatic LNs with prostate-specific antigen (PSA) decline, without any particular adverse events.

Therapeutic targeting of tumor suppressor genes

Carcinogenesis is a multistep process attributable to both gain-of-function mutations in oncogenes and loss-of-function mutations in tumor suppressor genes. Currently, most molecular targeted therapies are inhibitors of oncogenes, because inactivated tumor suppressor genes have proven harder to "drug." Nevertheless, in cancers, tumor suppressor genes undergo alteration more frequently than do oncogenes. In recent years, several promising strategies directed at tumor suppressor genes, or the pathways controlled by these genes, have emerged. Here, we describe advances in a number of different methodologies aimed at therapeutically targeting tumors driven by inactivated tumor suppressor genes.

Impact of decitabine on immunohistochemistry expression of the putative tumor suppressor genes FHIT, WWOX, FUS1 and PTEN in clinical tumor samples

BACKGROUND

Since tumor suppressor gene function may be lost through hypermethylation, we assessed whether the demethylating agent decitabine could increase tumor suppressor gene expression clinically. For fragile histidine triad (FHIT), WW domain-containing oxidoreductase (WWOX), fused in sarcoma-1 (FUS1) and phosphatase and tensin homolog (PTEN), immunohistochemistry scores from pre- and post-decitabine tumor biopsies (25 patients) were correlated with methylation of the long interspersed nuclear element-1 (LINE-1) repetitive DNA element (as a surrogate for global DNA methylation) and with tumor regression.

RESULTS

With negative staining pre-decitabine (score = 0), the number of patients converting to positive staining post-decitabine was 1 of 1 for FHIT, 3 of 6 for WWOX, 2 of 3 for FUS1 and 1 of 10 for PTEN. In tumors with low pre-decitabine tumor suppressor gene scores (≤150), expression was higher post-treatment in 8 of 8 cases for FHIT (P = 0.014), 7 of 17 for WWOX (P = 0.0547), 7 of 12 for FUS1 (P = 0.0726), and 1 of 16 for PTEN (P = 0.2034). If FHIT, WWOX and FUS1 were considered together, median pre- versus post-decitabine scores were 60 versus 100 (P = 0.0002). Overall, tumor suppressor gene expression change did not correlate with LINE-1 demethylation, although tumors converting from negative to positive had a median decrease in LINE-1 methylation of 24%, compared to 6% in those not converting (P = 0.069). Five of 15 fully evaluable patients had reductions in tumor diameter (range 0.2% to 33.4%). Of these, three had simultaneous increases in three tumor suppressor genes (including the two patients with the greatest tumor regression) compared to 2 of 10 with tumor growth (P = 0.25).

CONCLUSIONS

In tumors with low tumor suppressor gene expression, decitabine may be associated with increased expression of the tumor suppressor genes FHIT, FUS1, and WWOX, but not PTEN.

Advances in adenovirus-mediated p53 cancer gene therapy

INTRODUCTION

The tumor suppressor p53 gene regulates diverse cellular processes, such as cell-cycle arrest, senescence, apoptosis and autophagy, and it is frequently inactivated by genetic alterations in ∼ 50% of all types of human cancers. To restore wild-type p53 function in p53-inactivated tumors, adenovirus-mediated p53 gene therapy has been developed as a promising antitumor strategy in preclinical experiments and clinical studies.

AREAS COVERED

This review focuses on the clinical relevance of replication-deficient adenovirus vectors that carry the wild-type p53 gene (Ad-p53; Advexin, Gendicine and SCH-58500) in clinical studies of patients with various cancers and the future perspectives regarding conditionally replicating adenovirus vectors expressing the wild-type p53 gene (CRAd-p53; AdDelta24-p53, SG600-p53, OBP-702) in preclinical experiments. Moreover, the recent advances in our understanding of the molecular basis for the p53-mediated tumor suppression network induced by Ad-p53 and CRAd-p53 vectors and the combination therapies for promoting the therapeutic potential of adenovirus-mediated p53 gene therapy are discussed.

EXPERT OPINION

Exploration of the molecular mechanism underlying the p53-mediated tumor suppression network and the effective strategy for enhancing the p53-mediated cell death signaling pathway would provide novel insights into the improvement of clinical outcome in p53-based cancer gene therapy.

Cell cycle inhibitors for the treatment of NSCLC

INTRODUCTION

Lung cancer remains to be the leading cause of cancer-related death worldwide. Treatment of lung cancer still poses a significant challenge. Cell cycle is a tightly integrated process and is frequently aberrant in lung cancer. Cell cycle inhibitors have emerged as novel therapeutics, in anticipation of overcoming the unrestricted cell division and growth in lung cancer.

AREAS COVERED

In this article, we first address the potential roles of cell cycle proteins and cell cycle deregulation in the development of lung cancer. The review then provides an overview for several major categories of cell cycle inhibitors with particular attention to their tolerability and disease control in early phases of lung cancer trials.

EXPERT OPINION

Targeted agents against different components of cell cycle regulation, such as cyclin-dependent kinase, polo-like kinase, checkpoint kinase and aurora kinase, are currently in clinical development for lung cancer management. Their clinical benefits remain to be defined. When evaluated as single agents in lung cancer, cell cycle inhibitors are often associated with limited clinical activity and tolerable toxicities. The key challenges in the drug development are to understand resistance mechanisms and to identify predictive biomarkers that can potentially guide patient selection and optimize the utility of these targeted inhibitors.

Selective intra-arterial infusion of rAd-p53 with chemotherapy for advanced oral cancer: a randomized clinical trial

BACKGROUND

In this study, a combination of recombinant adenoviral p53 (rAd-p53) gene therapy and intra-arterial delivery of chemotherapeutic agents for treatment of oral squamous cell carcinoma was evaluated.

METHODS

In total, 99 patients with stage III or IV oral carcinoma who had refused or were ineligible for surgery were enrolled in a randomized, placebo-controlled, double-blind, phase III clinical trial. They were randomly assigned to group I (n = 35; intra-arterial infusion of rAd-p53 plus chemotherapy), group II (n = 33; intra-arterial infusion of rAd-p53 plus placebo chemotherapy), or group III (n = 31; intra-arterial infusion of placebo rAd-p53 plus chemotherapy).

RESULTS

The median length of follow-up was 36 months (range, 3 to 86 months). During follow-up, 16 patients in group I, 20 in group II, and 22 in group III died. Group I (48.5%) had a higher complete response rate than groups II (16.7%) and III (17.2%) (P = 0.006). The rate of non-responders in group I was significantly lower than that in groups II and III (P < 0.020). A log-rank test for survival rate indicated that group I had a significantly higher survival rate than group III (P = 0.019). The survival rate of patients with stage III but not stage IV oral cancer was significantly higher in group I than in group III (P = 0.015, P = 0.200, respectively). The survival rate of patients with stage IV did not differ significantly among the three groups. Or the 99 patients, 63 patients experienced adverse events of either transient flu-like symptoms or bone marrow suppression, while 13 patients had both these conditions together. No replication-deficient virus was detected in patient serum, urine, or sputum. rAd-p53 treatment increased Bax expression in the primary tumor of 80% of patients, as shown by immunohistochemical staining.

CONCLUSIONS

Intra-arterial infusion of combined rAd-p53 and chemotherapy significantly increased the survival rate of patients with stage III but not stage IV oral cancer, compared with intra-arterial chemotherapy. Intra-arterial infusion of combined rAd-p53 and chemotherapy may represent a promising alternative treatment for oral squamous cell carcinoma.

TRIAL REGISTRATION

ChiCTR-TRC-09000392 (Date of registration: 2009-05-18).

Induction of p53 expression and apoptosis by a recombinant dual-target MDM2/MDMX inhibitory protein in wild-type p53 breast cancer cells

The tumor suppressor gene p53 is often inactivated in breast cancer cells due to gene mutation or overexpression of its repressors (such as murine double minute 2 and murine double minute X). Inhibitors of murine double minute 2 (MDM2) and murine double minute X (MDMX) could lead to tumor suppression by restoration of p53 activity and such an approach is a promising strategy for future control of breast cancer. This study aimed to investigate the feasibility of the recombinant MDM2 and MDMX inhibitory protein in control of breast cancer in vitro. A cell-permeable dual-target MDM2/MDMX inhibitory protein was expressed in E. coli and incubated with p53 wild-type breast cancer cells. The data showed that this recombinant MDM2/MDMX inhibitory protein reduced the viability of MCF-7 and ZR-75-30 breast cancer cell lines and promoted cell cycle arrest and apoptosis by activation and stabilization of the p53 protein. Mechanistically, this MDM2/MDMX inhibitory protein increased the expression of p21, Bax and puma proteins, and inhibitory expression of MDM2 and MDMX proteins. This recombinant protein showed a better in vitro effect than that of nutlin-3α, a small molecule MDM2 inhibitor. The data further support the hypothesis that targeting of the p53 gene pathway could effectively control breast cancer.

Combined use of adenoviral vector Ad5/F35-mediated APE1 siRNA enhances the therapeutic efficacy of adenoviral-mediated p53 gene transfer in hepatoma cells in vitro and in vivo

Gene therapy has emerged as a novel therapeutic approach for the treatment of cancer. In order to establish a more effective therapeutic strategy against unresectable hepatocellular carcinoma (HCC), we evaluated, in the present study, the effects of combined treatment with adenoviral vector Ad5/F35-mediated APE1 siRNA (Ad5/F35-siAPE1) and adenoviral-mediated p53 gene transfer (Ad-p53) in hepatoma cells in vitro and in vivo. Infection of SMMC-7721 cells with Ad5/F35-siAPE1 resulted in a time- and dose-dependent decrease of APE1 protein, while Ad-p53 treatment led to a time- and dose-dependent increase of p53 protein expression. Ad5/F35-siAPE1 significantly enhanced the cytotoxic effect of SMMC-7721 cells to Ad-p53 in cell survival assays, associated with increased cell apoptosis. Moreover, administration of Ad5/F35-siAPE1 and Ad-p53 into nude mice resulted in tumor growth inhibition and apoptosis induction in SMMC-7721 xenografts compared to administration of either agent alone. These results suggest that combination of Ad5/F35-siAPE1 and Ad-p53 could be a promising gene therapeutic approach against human HCC.

Dual programmed cell death pathways induced by p53 transactivation overcome resistance to oncolytic adenovirus in human osteosarcoma cells

Tumor suppressor p53 is a multifunctional transcription factor that regulates diverse cell fates, including apoptosis and autophagy in tumor biology. p53 overexpression enhances the antitumor activity of oncolytic adenoviruses; however, the molecular mechanism of this occurrence remains unclear. We previously developed a tumor-specific replication-competent oncolytic adenovirus, OBP-301, that kills human osteosarcoma cells, but some human osteosarcoma cells were OBP-301-resistant. In this study, we investigated the antitumor activity of a p53-expressing oncolytic adenovirus, OBP-702, and the molecular mechanism of the p53-mediated cell death pathway in OBP-301-resistant human osteosarcoma cells. The cytopathic activity of OBP-702 was examined in OBP-301-sensitive (U2OS and HOS) and OBP-301-resistant (SaOS-2 and MNNG/HOS) human osteosarcoma cells. The molecular mechanism in the OBP-702-mediated induction of two cell death pathways, apoptosis and autophagy, was investigated in OBP-301-resistant osteosarcoma cells. The antitumor effect of OBP-702 was further assessed using an orthotopic OBP-301-resistant MNNG/HOS osteosarcoma xenograft tumor model. OBP-702 suppressed the viability of OBP-301-sensitive and -resistant osteosarcoma cells more efficiently than OBP-301 or a replication-deficient p53-expressing adenovirus (Ad-p53). OBP-702 induced more profound apoptosis and autophagy when compared with OBP-301 or Ad-p53. E1A-mediated miR-93/106b upregulation induced p21 suppression, leading to p53-mediated apoptosis and autophagy in OBP-702-infected cells. p53 overexpression enhanced adenovirus-mediated autophagy through activation of damage-regulated autophagy modulator (DRAM). Moreover, OBP-702 suppressed tumor growth in an orthotopic OBP-301-resistant MNNG/HOS xenograft tumor model. These results suggest that OBP-702-mediated p53 transactivation is a promising antitumor strategy to induce dual apoptotic and autophagic cell death pathways via regulation of miRNA and DRAM in human osteosarcoma cells.

Gene therapy of pancreatic cancer targeting the K-Ras oncogene

Ras mutations are present in ∼95% of pancreatic cancer (PC) cases leading to increased proliferation and apoptosis resistance. The aim of this study is to selectively kill Ras-transformed cells by overexpressing the pro-apoptotic protein, p53 upregulated modulator of apoptosis (PUMA) under a Ras-responsive promoter. Colo357, Panc1 and MiaPaca, PC cell lines harboring K-Ras mutations, normal rat IEC18 enterocytes, and their K-Ras transformed R1 counterparts, were tested. We constructed adenoviral vectors containing the PUMA gene downstream to: (1) Four or five repetitive Ras-responsive elements (Ad-PY4/PY5-PUMA) and (2) a negative control (Ad-SV40-PUMA). Cell viability was estimated by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and apoptosis was evaluated by FACS. In vivo potency of the adenoviruses was evaluated in athymic nude mice. Infection with Ad-PY4/PY5-PUMA markedly inhibited cell growth (∼40-50%), and apoptosis was detected in all cells with high Ras activity, whereas IEC18 cells remained unaffected. The control vector, Ad-SV40-PUMA, did not induce any cell death. Selective and high expression of PUMA was detected in Ad-PY4-PUMA-infected cells. In vivo, Ad-PY4-PUMA inhibited by ∼35% the growth of established tumors compared with the Ad-SV40-PUMA. Selective overexpression of PUMA efficiently inhibits the growth of Ras-transformed cells while sparing the normal ones. This treatment modality may become a useful, effective and safe approach to selectively target Ras-mutated tumor cells.

Phase I clinical trial of systemically administered TUSC2(FUS1)-nanoparticles mediating functional gene transfer in humans

Background

Tumor suppressor gene TUSC2/FUS1 (TUSC2) is frequently inactivated early in lung cancer development. TUSC2 mediates apoptosis in cancer cells but not normal cells by upregulation of the intrinsic apoptotic pathway. No drug strategies currently exist targeting loss-of–function genetic abnormalities. We report the first in-human systemic gene therapy clinical trial of tumor suppressor gene TUSC2.

Methods

Patients with recurrent and/or metastatic lung cancer previously treated with platinum-based chemotherapy were treated with escalating doses of intravenous N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP):cholesterol nanoparticles encapsulating a TUSC2 expression plasmid (DOTAP:chol-TUSC2) every 3 weeks.

Results

Thirty-one patients were treated at 6 dose levels (range 0.01 to 0.09 milligrams per kilogram). The MTD was determined to be 0.06 mg/kg. Five patients achieved stable disease (2.6–10.8 months, including 2 minor responses). One patient had a metabolic response on positron emission tomography (PET) imaging. RT-PCR analysis detected TUSC2 plasmid expression in 7 of 8 post-treatment tumor specimens but not in pretreatment specimens and peripheral blood lymphocyte controls. Proximity ligation assay, performed on paired biopsies from 3 patients, demonstrated low background TUSC2 protein staining in pretreatment tissues compared with intense (10–25 fold increase) TUSC2 protein staining in post-treatment tissues. RT-PCR gene expression profiling analysis of apoptotic pathway genes in two patients with high post-treatment levels of TUSC2 mRNA and protein showed significant post-treatment changes in the intrinsic apoptotic pathway. Twenty-nine genes of the 82 tested in the apoptosis array were identified by Igenuity Pathway Analysis to be significantly altered post-treatment in both patients (Pearson correlation coefficient 0.519; p<0.01).

Conclusions

DOTAP:chol-TUSC2 can be safely administered intravenously in lung cancer patients and results in uptake of the gene by human primary and metastatic tumors, transgene and gene product expression, specific alterations in TUSC2-regulated pathways, and anti-tumor effects (to our knowledge for the first time for systemic DOTAP:cholesterol nanoparticle gene therapy).

Trial Registration

ClinicalTrials.gov NCT00059605

A novel apoptotic mechanism of genetically engineered adenovirus-mediated tumour-specific p53 overexpression through E1A-dependent p21 and MDM2 suppression

Oncolytic viruses engineered to replicate in tumour cells but not in normal cells could be used as tumour-specific vectors carrying the therapeutic genes. We previously developed a telomerase-specific oncolytic adenovirus, OBP-301, that causes cell death in human cancer cells with telomerase activities. Here, we further modified OBP-301 to express the wild-type p53 tumour suppressor gene (OBP-702), and investigated whether OBP-702 induces stronger antitumour activity than OBP-301. The antitumour effect of OBP-702 was compared to that of OBP-301 on OBP-301-sensitive (H358 and H460) and OBP-301-resistant (T.Tn and HSC4) human cancer cells. OBP-702 suppressed the viability of both OBP-301-sensitive and OBP-301-resistant cancer cells more efficiently than OBP-301. OBP-702 caused increased apoptosis compared to OBP-301 or a replication-deficient adenovirus expressing the p53 gene (Ad-p53) in H358 and T.Tn cells. Adenovirus E1A-mediated p21 and MDM2 downregulation was involved in the apoptosis caused by OBP-702. Moreover, OBP-702 significantly suppressed tumour growth in subcutaneous tumour xenograft models compared to monotherapy with OBP-301 or Ad-p53. Our data demonstrated that OBP-702 infection expressed adenovirus E1A and then inhibited p21 and MDM2 expression, which in turn efficiently induced apoptotic cell death. This novel apoptotic mechanism suggests that the p53-expressing OBP-702 is a promising antitumour reagent for human cancer and could improve the clinical outcome.

A simple detection system for adenovirus receptor expression using a telomerase-specific replication-competent adenovirus

Adenovirus serotype 5 (Ad5) is frequently used as an effective vector for induction of therapeutic transgenes in cancer gene therapy or of tumor cell lysis in oncolytic virotherapy. Ad5 can infect target cells through binding with the coxsackie and adenovirus receptor (CAR). Thus, the infectious ability of Ad5-based vectors depends on the CAR expression level in target cells. There are conventional methods to evaluate the CAR expression level in human target cells, including flow cytometry, western blotting and immunohistochemistry. Here, we show a simple system for detection and assessment of functional CAR expression in human tumor cells, using the green fluorescent protein (GFP)-expressing telomerase-specific replication-competent adenovirus OBP-401. OBP-401 infection induced detectable GFP expression in CAR-expressing tumor cells, but not in CAR-negative tumor cells, nor in CAR-positive normal fibroblasts, 24 h after infection. OBP-401-mediated GFP expression was significantly associated with CAR expression in tumor cells. OBP-401 infection detected tumor cells with low CAR expression more efficiently than conventional methods. OBP-401 also distinguished CAR-positive tumor tissues from CAR-negative tumor and normal tissues in biopsy samples. These results suggest that GFP-expressing telomerase-specific replication-competent adenovirus is a very potent diagnostic tool for assessment of functional CAR expression in tumor cells for Ad5-based antitumor therapy.

Gene therapy for lung neoplasms

Both advanced-stage lung cancer and malignant pleural mesothelioma are associated with a poor prognosis. Advances in treatment regimens for both diseases have had only a modest effect on their progressive course. Gene therapy for thoracic malignancies represents a novel therapeutic approach and has been evaluated in several clinical trials. Strategies have included induction of apoptosis, tumor suppressor gene replacement, suicide gene expression, cytokine-based therapy, various vaccination approaches, and adoptive transfer of modified immune cells. This review considers the clinical results, limitations, and future directions of gene therapy trials for thoracic malignancies.

Recent advances in intervention in markovian regulatory networks

Markovian regulatory networks constitute a class of discrete state-space models used to study gene regulatory dynamics and discover methods that beneficially alter those dynamics. Thereby, this class of models provides a framework to discover effective drug targets and design potent therapeutic strategies. The salient translational goal is to design therapeutic strategies that desirably modify network dynamics via external signals that vary the expressions of a control gene. The objective of an intervention strategy is to reduce the likelihood of the pathological cellular function related to a disease. The task of finding an effective intervention strategy can be formulated as a sequential decision making problem for a pre-defined cost of intervention and a cost-per-stage function that discriminates the gene-activity profiles. An effective intervention strategy prescribes the actions associated with an external signal that result in the minimum expected cost. This strategy in turn can be used as a treatment that reduces the long-run likelihood of gene expressions favorable to the disease. In this tutorial, we briefly summarize the first method proposed to design such therapeutic interventions, and then move on to some of the recent refinements that have been proposed. Each of these recent intervention methods is motivated by practical or analytical considerations. The presentation of the key ideas is facilitated with the help of two case studies.

MicroRNAs as potential target gene in cancer gene therapy of gastrointestinal tumors

INTRODUCTION

MicroRNA (miRNA) is a small non-coding RNA, which negatively regulates the expression of many target genes, thereby contributing to the modulation of diverse cell fates. Recent advances in molecular biology have revealed the potential role of miRNAs in tumor initiation, progression and metastasis. Aberrant regulation of miRNAs has been frequently reported in a variety of cancers, including gastrointestinal tumors, suggesting that cancer-related miRNAs are promising as novel biomarkers for tumor diagnosis and are potential target genes for cancer gene therapy against gastrointestinal tumors.

AREAS COVERED

The review focuses on the role of specific miRNAs (miR-192/194/215 and miR-7) in the differentiation of gastrointestinal epithelium and on the role of tumor-suppressive (miR-34, miR-143, miR-145) and oncogenic miRNAs (miR-21, miR-17-92 cluster) in gastrointestinal tumors. Furthermore, the potential role of miRNAs as novel biomarkers and target genes for cancer gene therapy against gastrointestinal tumors are discussed. We will also outline the potential clinical application of miRNAs for tumor diagnosis and cancer gene therapy against gastrointestinal tumors.

EXPERT OPINION

Exploration of tumor-related miRNAs would provide important opportunities for the development of novel cancer gene therapies aimed at normalizing the critical miRNAs that are deregulated in gastrointestinal tumors.

Tumor suppressor gene-based nanotherapy: from test tube to the clinic

Cancer is a major health problem in the world. Advances made in cancer therapy have improved the survival of patients in certain types of cancer. However, the overall five-year survival has not significantly improved in the majority of cancer types. Major challenges encountered in having effective cancer therapy are development of drug resistance by the tumor cells, nonspecific cytotoxicity, and inability to affect metastatic tumors by the chemodrugs. Overcoming these challenges requires development and testing of novel therapies. One attractive cancer therapeutic approach is cancer gene therapy. Several laboratories including the authors' laboratory have been investigating nonviral formulations for delivering therapeutic genes as a mode for effective cancer therapy. In this paper the authors will summarize their experience in the development and testing of a cationic lipid-based nanocarrier formulation and the results from their preclinical studies leading to a Phase I clinical trial for nonsmall cell lung cancer. Their nanocarrier formulation containing therapeutic genes such as tumor suppressor genes when administered intravenously effectively controls metastatic tumor growth. Additional Phase I clinical trials based on the results of their nanocarrier formulation have been initiated or proposed for treatment of cancer of the breast, ovary, pancreas, and metastatic melanoma, and will be discussed.

TP53 mutations in nonsmall cell lung cancer

The tumor suppressor gene TP53 is frequently mutated in human cancers. Abnormality of the TP53 gene is one of the most significant events in lung cancers and plays an important role in the tumorigenesis of lung epithelial cells. Human lung cancers are classified into two major types, small cell lung cancer (SCLC) and nonsmall cell lung cancer (NSCLC). The latter accounts for approximately 80% of all primary lung cancers, and the incidence of NSCLC is increasing yearly. Most clinical studies suggest that NSCLC with TP53 alterations carries a worse prognosis and may be relatively more resistant to chemotherapy and radiation. A deep understanding of the role of TP53 in lung carcinogenesis may lead to a more reasonably targeted clinical approach, which should be exploited to enhance the survival rates of patients with lung cancer. This paper will focus on the role of TP53 in the molecular pathogenesis, epidemiology, and therapeutic strategies of TP53 mutation in NSCLC.

Optimal constrained stationary intervention in gene regulatory networks

A key objective of gene network modeling is to develop intervention strategies to alter regulatory dynamics in such a way as to reduce the likelihood of undesirable phenotypes. Optimal stationary intervention policies have been developed for gene regulation in the framework of probabilistic Boolean networks in a number of settings. To mitigate the possibility of detrimental side effects, for instance, in the treatment of cancer, it may be desirable to limit the expected number of treatments beneath some bound. This paper formulates a general constraint approach for optimal therapeutic intervention by suitably adapting the reward function and then applies this formulation to bound the expected number of treatments. A mutated mammalian cell cycle is considered as a case study.