Adenoviral-mediated p53 gene transfer to non-small cell lung cancer through endobronchial injection

Efficacy of bronchoscopic intratumoral injection of endostar and cisplatin in lung squamous cell carcinoma patients underwent conventional chemoradiotherapy

Bronchoscopy has been widely used for the therapy of lung cancer. This study aimed to evaluate the therapeutic efficacy and adverse reactions of bronchoscopic intratumoral injection of endostar and cisplatin in patients with lung squamous cell carcinoma (LSCC). A total of 40 LSCC patients who underwent conventional chemoradiotherapy were included in this study, and 20 of them received a bronchoscopic injection of endostar and cisplatin as an additive therapeutic modality (treatment group). The clinical response rate, progression-free survival (PFS), and adverse reactions of the patients were compared and analyzed. The treatment group had better short- and long-term therapeutic efficacy compared to the control group, but no significant differences were observed between the two therapeutic regimens in adverse reactions. Elderly and advanced LSCC patients had worse therapeutic efficacy and a high probability of adverse reactions after the therapy. Collectively, our analysis data demonstrated that the bronchoscopic intratumoral injection of endostar and cisplatin had improved therapeutic efficacy, and the cardiovascular adverse reactions were within the controllable range in the treatment of LSCC in clinical practices.

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.

Papillary squamous cell carcinoma successfully treated with bronchoscopic intratumoral injections of cisplatin and Endostar: a case report

Squamous cell carcinoma (SCC) is a malignant epithelial tumor originating from the bronchial epithelium that shows keratosis and/or intercellular bridges. Papillary squamous cell carcinoma (PSCC) is an extremely rare subtype of SCC that manifests with a unique intrabronchial papillary growth pattern. Surgical resection is still the first recommendation for localized noninvasive SCC. However, some patients are not candidates for surgical resection. With the development of interventional pulmonology, bronchoscopic interventional therapy has played a key role in the treatment of central airway tumors. Here, we report a case of noninvasive PSCC in the airway treated with an electric snare, argon plasma coagulation (APC), and cryotherapy. After removing the tumor by electrotomy, cryotherapy, and APC, the tumor was injected with Endostar 15 mg (3 ml) and cisplatin 20 mg (diluted to 3 ml with 0.9% normal saline) in six separate sites, once every 21 days. The tumor was eliminated, and the treatment was stopped after four treatment cycles. During the 1-year follow-up, there was no recurrence of PSCC in the airway. In this case, submucosal injections of Endostar combined with cisplatin was a feasible and effective endoscopic method for treating a low-grade intratracheal malignant tumor.

Alternative methods for local ablation-interventional pulmonology: a narrative review

OBJECTIVE

To discuss and summarise the background and recent advances in the approach to bronchoscopic ablative therapies for lung cancer, focusing on focal parenchymal lesions.

BACKGROUND

This series focusses on the challenges highlighted by increasing recognition of the prognostically more favourable oligometastatic disease rather than the more frequent, but prognostically poor, high tumour burden metastatic disease. While surgery, stereotactic body radiation therapy (SBRT), and trans-thoracic percutaneous ablative techniques such as microwave (MWA) and radiofrequency ablation (RFA) are well recognised options for selected cases of pulmonary oligometastasis, bronchoscopic approaches to pulmonary tumour ablation are becoming realistic alternatives. An underlying tenet driving research and implementation in this domain is that percutaneous ablative techniques are obliged to traverse the pleura leading to a high rate of pneumothorax, and risks also goes up for peri-vascular lesions. Historically low yield bronchoscopic targeting of isolated peripheral tumors have significantly improved by incorporating multi-modality high resolution imaging and processing, including navigation planning and real-time image guidances (ultrasound, electromagnetic navigation, cone-beam CT). Combining advanced image guidance with ablative technology adaptations for bronchoscopic delivery opens up the options for high dose local ablative therapies that may reduce transthoracic complications and provide palliative to curative options for limited stage primary and oligometastatic diseases.

METHODS

We conduct a narrative review of the literature summarizing the history of bronchoscopic tumor ablation approaches, technical details including biologic rational for their uses, and current evidence for each modality, as well as investigations into future applications. Because of the relative paucity of prospective studies, we have been very inclusive in our inclusion of experiences from the published clinical databases.

CONCLUSIONS

Whilst surgical resection and SBRT remain the current mainstay of curative therapies for peripheral cancers, in the foreseeable future, developments and further research will see bronchoscopic ablative therapies become viable lung sparing alternatives in those deemed suitable. The future is bright.

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.

Bronchoscopic Therapies for Peripheral Lung Malignancies

Current advances in guided bronchoscopy methods permit minimally invasive access to essentially any area of the lungs. This provides a potential means to treat patients with localized lung malignancies who might not otherwise tolerate conventional treatment, which commonly relies on surgical resection. Ablation methods have long been used for bronchoscopic treatment of central airway malignancies and percutaneous treatment of peripheral lung cancer. This article reviews ablation technologies being adapted for use with guided bronchoscopy and the current state of investigation for the treatment of peripheral lung malignancies.

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.

Recombinant human adenovirus-p53 improves the outcome of mid-late stage pancreatic cancer via arterial infusion

The present study aimed to investigate the therapeutic efficacy and clinical value of recombinant human adenovirus-p53 (rAd-p53) perfusion via the pancreatic artery for the treatment of mid-late stage pancreatic cancer. rAd-p53 (2×10¹² virus particles) in 6 ml normal saline was pushed (intravenous bolus) into the gastroduodenal and superior pancreaticoduodenal arteries via interventional superselection, with the catheter retained for subsequent drug administration at a 3-day interval for 4 cycles. Tumor changes in all patients were observed to evaluate tumor response by computed tomography (CT) at 2, 8 and 16 weeks post-treatment. The following improvements were noted in the 23-patient cohort: A total of 73.9% (17/23) of patients demonstrated significant tumor shrinkage (>20%); the symptoms of abdominal and back pain were relieved in 15 patients; the survival time was >12 months in 1 patient and >6 months in 14 patients; the patient's general condition, including appetite, was improved in 13 patients; body weight was increased in 9 patients; jaundice was attenuated in 12 patients; and ascites subsided in 10 patients. However, the therapeutic outcome was poor in 2 patients whose tumors size did not show significant change after treatment as detected by CT. These 2 patients succumbed within 6 months. In conclusion, rAd-p53 perfusion via the pancreatic artery is a safe and minimally invasive option for the treatment of mid-late stage pancreatic cancer.

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.

Techniques of endoscopic airway tumor treatment

Interventional bronchoscopy has a predominant role in the management of both early and advanced-stage airway tumors. Given the very poor prognosis of lung cancer, there is a need for new tools to improve early detection and bronchoscopic treatment of endo-bronchial precancerous lesions. In more advanced stages, interventional bronchoscopy plays an important role, as nearly a third of lung cancers lead to proximal airway obstruction. This will cause great discomfort or even life-threatening symptoms related to local extension, such as dyspnea, post-obstructive pneumonia, and hemoptysis. Surgery for very locally advanced disease is only effective for a limited number of patients and the effects of conventional antitumor therapies, like radiation therapy or chemotherapy, are inconstant and are too delayed in a palliative context. In this review, we aim to provide pulmonologists with an exhaustive technical overview of (I) the bronchoscopic management of benign endobronchial lesions; (II) the bronchoscopic management of malignant tumors, including the curative treatment of localized lesions and palliative management of malignant proximal airway stenosis; and (III) descriptions of the emerging endoscopic techniques used to treat peripheral lung tumors.

Gene Therapy for Human Lung Adenocarcinoma Using a Suicide Gene Driven by a Lung-Specific Promoter Delivered by JC Virus-Like Particles

Lung adenocarcinoma, the most commonly diagnosed type of lung cancer, has a poor prognosis even with combined surgery, chemotherapy, or molecular targeted therapies. Most patients are diagnosed with an in-operable advanced or metastatic disease, both pointing to the necessity of developing effective therapies for lung adenocarcinoma. Surfactant protein B (SP-B) has been found to be overexpressed in lung adenocarcinoma. In addition, it has also been demonstrated that human lung adenocarcinoma cells are susceptible to the JC polyomavirus (JCPyV) infection. Therefore, we designed that the JCPyV virus-like particle (VLP) packaged with an SP-B promoter-driven thymidine kinase suicide gene (pSPB-tk) for possible gene therapy of human lung adenocarcinoma. Plasmids expressing the GFP (pSPB-gfp) or thymidine kinase gene (pSPB-tk) under the control of the human SP-B promoter were constructed. The promoter's tissue specificity was tested by transfection of pSPB-gfp into A549, CH27, and H460 human lung carcinoma cells and non-lung cells. The JCPyV VLP's gene transfer efficiency and the selective cytotoxicity of pSPB-tk combined with ganciclovir (GCV) were tested in vitro and in a xenograft mouse model. In the current study, we found that SP-B promoter-driven GFP was specifically expressed in human lung adenocarcinoma (A549) and large cell carcinoma (H460) cells. JCPyV VLPs were able to deliver a GFP reporter gene into A549 cells for expression. Selective cytotoxicity was observed in A549 but not non-lung cells that were transfected with pSPB-tk or infected with pSPB-tk-carrying JCPyV VLPs. In mice injected with pSPB-tk-carrying JCPyV VLPs through the tail vein and treated with ganciclovir (GCV), a potent 80% inhibition of growth of human lung adenocarcinoma nodules resulted. The JCPyV VLPs combined with the use of SP-B promoter demonstrates effectiveness as a potential gene therapy against human lung adenocarcinoma.

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).

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.

Nanoparticle-mediated p53 gene therapy for tumor inhibition

The p53 tumor suppressor gene is mutated in 50% of human cancers, resulting in more aggressive disease with greater resistance to chemotherapy and radiation therapy. Advances in gene therapy technologies offer a promising approach to restoring p53 function. We have developed polymeric nanoparticles (NPs), based on poly (lactic-co-glycolic acid), that provide sustained intracellular delivery of plasmid DNA, resulting in sustained gene expression without vector-associated toxicity. Our previous studies with p53 gene-loaded NPs (p53NPs) demonstrated sustained antiproliferative effects in cancer cells in vitro. The objective of this study was to evaluate the efficacy of p53NPs in vivo. Tumor xenografts in mice were established with human p53-null prostate cancer cells. Animals were treated with p53NPs by either local (intratumoral injection) or systemic (intravenous) administration. Controls included saline, p53 DNA alone, and control NPs. Mice treated with local injections of p53NPs demonstrated significant tumor inhibition and improved animal survival compared with controls. Tumor inhibition corresponded to sustained and greater p53 gene and protein expression in tumors treated with p53NPs than with p53 DNA alone. A single intravenous dose of p53NPs was successful in reducing tumor growth and improving animal survival, although not to the same extent as with local injections. Imaging studies showed that NPs accumulate in tumor tissue after intravenous injection; however, further improvement in tumor targeting efficiency of p53NPs may be needed for better outcome. In conclusion, the NP-mediated p53 gene therapy is effective in tumor growth inhibition. NPs may be developed as nonviral vectors for cancer and other genetic diseases.

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.

Clinical trials of GMP products in the gene therapy field

Advances in gene therapy are increasingly leading to clinical assessment in many fields of medicine with diverse approaches. The basic science stems from approaches aimed at different functions such as correcting a missing/abnormal gene, altering the proportion or expression of normal genes to augment a physiological process or using this principle to destroy malignant or infected cells. As the technology advances, it is increasingly important to ensure that clinical trials answer the questions that need to be asked. In this chapter we review examples of published clinical trials, resources for accessing information about registered trials, the process of regulating trials, good clinical practice, and good manufacturing practice as well as summarising the approach taken by regulatory authorities in reviewing applications for the introduction of products for use in the clinic.

Gene therapy for mesothelioma and lung cancer

Both malignant pleural mesothelioma and advanced stage lung cancer are associated with a poor prognosis. Unfortunately, current treatment regimens 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 a number of clinical trials over the last two decades. Using viral vectors or anti-sense RNA, 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 will consider the clinical results, limitations, and future directions of gene therapy trials for thoracic malignancies.

In vitro and clinical studies of gene therapy with recombinant human adenovirus-p53 injection for oral leukoplakia

PURPOSE

Oral leukoplakia is a well-recognized precancerous lesion of squamous cell carcinoma. When accompanied with abnormal p53 expression, it suffered a higher risk of canceration. The present study was carried out to test whether the recombinant human adenovirus-p53 could introduce wild-type p53 gene to oral leukoplakia cells and induce cell cycle arrest and apoptosis.

EXPERIMENTAL DESIGN

We select p53(-) oral dysplastic keratinocyte POE-9n, to observe the growth inhibition, cell cycle change, apoptosis-induced effects, and elaborate the corresponding molecular mechanism of recombinant adenovirus-p53 on POE-9n cells. Meanwhile, we evaluate the feasibility, safety, and biological activity of multipoints intraepithelial injections of recombinant adenovirus-p53 in 22 patients with dysplastic oral leukoplakia.

RESULTS

Exogenous p53 could be successfully transduced into POE-9n cells by recombinant adenovirus-p53. The optimal infecting titer in this study was multiplicity of infection (MOI) = 100. Recombinant adenovirus-p53 could strongly inhibit cell proliferation, induce apoptosis, and arrest cell cycle in stage G(1) in POE-9n cells by inducing p21(CIP/WAF) and downregulating bcl-2 expression. In the posttreatment patients, p53 protein and p21(CIP/WAF) protein expression were significantly enhanced, yet bcl-2 protein presented low expression. Sixteen patients showed clinical response to the treatment, and 14 patients showed obvious histopathologic improvement.

CONCLUSION

Intraepithelial injections of recombinant human adenovirus-p53 were safe, feasible, and biologically active for patients with dysplastic oral leukoplakia.

Radiosensitivity of canine osteosarcoma cells transfected with wild-type p53 in vitro

The p53 gene is one of the important tumour suppressor genes that are involved with the cell survival signal pathway. One of the major functions of the p53 protein is to organize cell cycle regulation and induction of apoptosis for cellular genetic stability. It has been documented that more than 50% of all human cancers include a p53 mutation. We evaluated the difference in radiosensitivity between upregulating the expression of canine wild-type p53 (cp53) in cultured osteosarcoma (D17) cells and naive D17 cells in vitro. We found that upregulating transfected cp53 D17 cells increased their radiation sensitivity in vitro, and there was a significant decrease (P < 0.009) in survival between cp53-transfected D17 cells and naive D17 cells. In this experiment, a p53 enhancement ratio (p53ER) reached approximately 3.0 at high doses. The transfected cp53 D17 cells were significantly more radiosensitive at all doses evaluated than naive D17 cells, except at 1 Gy where too few data points were available. The p53ER increased rapidly at doses less than 4 Gy, achieving a maximum of about 3.0 for doses of 4 Gy and above. This study shows the enhanced radiosensitivity of the transfected p53 at clinically relevant doses.

A novel triple-regulated oncolytic adenovirus carrying p53 gene exerts potent antitumor efficacy on common human solid cancers

Conditionally replicating adenoviruses (CRAd) can replicate specifically in cancer cells and lyse them. The CRAds were widely used in the preclinical and clinical studies of cancer therapy. We hypothesize that more precisely regulated replication of CRAds may further improve the vector safety profile and enhance its antitumor efficacy. Here, a triple-regulated CRAd carrying p53 gene expression cassette, SG600-p53, was engineered. In SG600-p53, the E1a gene with a deletion of 24 nucleotides within CR2 region is controlled under the human telomerase reverse transcriptase (hTERT) promoter, the E1b gene expression is directed by the hypoxia response element (HRE), whereas the p53 gene is controlled by the cytomegalovirus promoter. The precise triple-regulation endows SG600-p53 with enhanced antitumor potential and improved safety profile. The tumor-selective replication of this virus and its antitumor efficacy were characterized in several tumor cell lines in vitro and in xenograft models of human non-small cell lung cancer in nude mice. With the selective replication and oncolysis, it was found by ELISA assay that SG600-p53 expressed p53 efficiently in cancer cells. In NCI-H1299 tumor xenograft models, SG600-p53 displayed a tumor-selective killing capacity. At a dose of 2 x 10(9) plaque-forming units, SG600-p53 could completely inhibit the tumor growth and more effective than replication-defective Ad-p53. Histopathologic examination revealed that SG600-p53 administration resulted in cancer cell apoptosis. We concluded that the triple-regulated SG600-p53, as a more potent and safer antitumor therapeutic, could provide a new strategy for cancer biotherapy.

Isolated limb perfusion: a novel delivery system for wild-type p53 and fiber-modified oncolytic adenoviruses to extremity sarcoma

Isolated limb perfusion (ILP) is a limb salvage surgical modality used to deliver chemotherapy and biologic agents to locally advanced and recurrent extremity soft tissue sarcoma (STS), and may be readily tailored for delivery of gene therapy. We set out to test the feasibility of delivering AdFLAGp53 (replication incompetent adenovirus bearing FLAG-tagged wild-type p53) and Ad.hTC.GFP/E1a.RGD (a fiber-modified, replication selective oncolytic adenovirus) into human leiomyosarcoma xenografts by ILP. Nude rats bearing SKLMS-1 tumors in their hind limbs underwent ILP with escalating doses of AdLacZ or AdFLAGp53 (study 1), or with Ad.CMV.GFP.RGD or Ad.hTC.GFP/E1a.RGD (study 2) following in vitro confirmation of therapeutic potential in STS cell lines and strains. Seventy-two hours after delivery, reverse transcription-polymerase chain reaction confirmed FLAGp53 expression, and immunohistochemistry confirmed diffuse upregulation of p21CIP1/WAF1 in ILP-treated tumors. Ad.hTC.GFP/E1a.RGD perfused tumors demonstrated robust macroscopic transgene expression throughout their substance, but not in perfused normal tissues, 21 days after delivery. Intra-tumoral viral replication was confirmed by immunohistochemical staining for early (E1a) and late (hexon) viral protein expression. Terminal deoxynucleotidyl transferase-mediated-digoxigenin nick end-labeling staining identified foci of cell death within regions of viral replication. In conclusion, therapeutic adenoviral gene therapy against limb borne human STS can be successfully delivered by ILP and warrants further investigation.

Gene therapy for lung cancer

Lung cancer patients suffer a 15% overall survival despite advances in chemotherapy, radiation therapy, and surgery due to the usual finding of advanced disease at diagnosis. Attempts to improve survival in advanced disease using various combinations of chemotherapy have demonstrated that no regimen is superior, suggesting a therapeutic plateau and the need for novel, more specific, and less toxic therapeutic strategies. Techniques have been developed that allow transfer of functional genes into mammalian cells, such as those that block activated tumor-promoting oncogenes and/or those that replace inactivated tumor-suppressing or apoptosis-promoting genes. This article will discuss the therapeutic implications of these molecular changes associated with bronchogenic carcinomas, and will then review the status of gene therapies for treatment of lung cancer.

Gene therapy for lung cancer

Lung cancer patients suffer a 15% overall survival despite advances in chemotherapy, radiation therapy, and surgery. This unacceptably low survival rate is due to the usual finding of advanced disease at diagnosis. However, multimodality strategies using conventional therapies only minimally improve survival rates even in early stages of lung cancer. Attempts to improve survival in advanced disease using various combinations of platinum-based chemotherapy have demonstrated that no regimen is superior, suggesting a therapeutic plateau and the need for novel, more specific, and less toxic therapeutic strategies. Over the past three decades, the genetic etiology of cancer has been gradually delineated, albeit not yet completely. Understanding the molecular events that occur during the multistep process of bronchogenic carcinogenesis may make these tasks more surmountable. During these same three decades, techniques have been developed which allow transfer of functional genes into mammalian cells. For example, blockade of activated tumor-promoting oncogenes or replacement of inactivated tumor-suppressing or apoptosis-promoting genes can be achieved by gene therapy. This article will discuss the therapeutic implications of these molecular changes associated with bronchogenic carcinomas and will then review the status of gene therapies for treatment of lung cancer.

Coxsackievirus and adenovirus receptor expression in non-malignant lung tissues and clinical lung cancers

Adenoviral vector mediated gene delivery has been applied in clinical trials and mechanistic studies to explore new treatment approaches for lung cancers. The expression of coxsackievirus adenovirus receptor (CAR), the primary receptor for the most commonly used adenovirus serotype 5 (Ad5)-based vectors, predominantly determines the permissiveness of lung cancer cells. CAR expression is also suggested to modulate tumor cell proliferation capacity. Here, we studied CAR expression in archival lung cancer specimens by using well-characterized CAR 72 antibodies. High levels of CAR expression were observed in most of the 32 cases of squamous cell carcinoma lung cancers and in all the five cases of small cell lung cancers investigated. In contrast, high levels of CAR expression were detected only in 6 of 22 adenocarcinoma lung cancers. The relative levels of CAR expression did not correlate with the pathologic grade in lung cancers, and was thus inconsistent with a role of modulating cancer cell proliferation. Of note, CAR expression was not detected in non-malignant alveolar cells. Our data suggest a preferred utility of Ad5 vector mediated gene delivery to squamous cell carcinoma lung cancers, small cell lung cancers, but not to the majority of adenocarcinoma lung cancers.

p53 as a target for anti-cancer drug development

Loss of p53 function compromises genetic homeostasis in cells exhibiting deregulated DNA replication and/or DNA damage, and prevents normal cytotoxic responses to cancer therapies. Genetic and pharmacological approaches are being developed with the ultimate goal of restoring or controlling p53 functions in cancer patients. Progress has recently been made in the clinical use of replication-deficient virus carrying wt-TP53 (Ad5CMV-p53) and/or cancer-selective oncolytic adenoviruses (ONYX-015). These strategies demonstrated clinical activity as monotherapy and were synergistic with traditional chemotherapy agents in the treatment of some types of cancer. In addition, pharmacological methods are under development to either stimulate wild-type p53 protein function, or induce p53 mutant proteins to resume wild-type functions. These methods are based on small chemicals (CP-31388, PRIMA-1), peptides (CDB3) or single-chain Fv antibody fragments corresponding to defined p53 domains. Here, we discuss the mechanisms underlying these approaches and their perspectives for cancer therapy.

Gene therapy for lung cancer

Over the past three decades, the molecular biology of lung cancer has been progressively delineated. Concurrently, gene therapy techniques have been developed that allow targeting or replacement of dysfunctional genes in cancer cells, such as activated tumor-promoting oncogenes, inactivated tumor-suppressing, or apoptosis-promoting genes. This article will review the therapeutic implications of molecular changes associated with non-small cell lung cancer and the status of gene therapy.

Transbronchial Needle Injection: A Systematic Review of a New Diagnostic and Therapeutic Paradigm

BACKGROUND AND OBJECTIVE

Transbronchial needle catheters are commonly used during flexible and rigid bronchoscopy for needle aspiration. The use of these catheters can be expanded by employing the technique of transbronchial needle injection.

METHODS AND RESULTS

By injecting lesions in the airways, peribronchial structures, mediastinum, or lung parenchyma, transbronchial needle injection has been applied to the treatment of lung cancer, inflammatory disorders of the airways, recurrent respiratory papillomatosis, as well as bronchopleural fistulas. Diagnostic applications have included the localization of peripheral lung nodules as well as sentinel lymph nodes.

CONCLUSIONS

Our review defines this bronchoscopic technique and summarizes its various reported applications.

Adenoviral Strategies for the Gene Therapy of Cancer

Despite slow clinical progress, efforts to develop specific nontoxic cancer gene therapies are increasing exponentially. Adenoviral vectors are one of the most popular vehicles for gene transfer currently being used in worldwide clinical trials for cancer. Over the past decade our knowledge of the adenoviral life cycle together with the discovery of novel tumor antigens has permitted the targeting of adenoviral vectors to specific tumors. Targeting adenoviral vectors to tumors is crucial for their use in clinical applications in order to allow for systemic administration and the use of reduced vector doses. In addition, novel approaches to tumor killing have also been explored, which will have greater potency and selectivity than currently available treatments such as chemotherapy or radiation. This review discusses the basic concepts behind the use of adenoviral vectors for cancer gene therapy and their potential for clinical application, as well as ongoing and completed clinical trials.

WWOX gene restoration prevents lung cancer growth in vitro and in vivo

The WWOX (WW domain containing oxidoreductase) gene at the common fragile site, FRA16D, is altered in many types of cancer, including lung cancer. We have examined the tumor suppressor function of WWOX in preclinical lung cancer models. The WWOX gene was expressed in lung cancer cell lines through recombinant adenovirus (Ad) infection (Ad-WWOX), and through a drug [ponasterone A, (ponA)]-inducible system. After WWOX restoration in vitro, endogenous Wwox protein-negative cell lines (A549, H460, and H1299) underwent apoptosis through activation of the intrinsic apoptotic caspase cascade in A549 and H460 cells. Ectopic expression of Wwox caused dramatic suppression of tumorigenicity of A549, H460, and H1299 cells in nude mice after Ad-WWOX infection and after ponA induction of Wwox expression in H1299 lung cancer cells. Tumorigenicity and in vitro growth of U2020 (Wwox-positive) lung cancer cells was unaffected by Wwox overexpression. This study confirms that WWOX is a tumor suppressor gene and is highly effective in preventing growth of lung cancer xenografts, whether introduced through viral infection or by induction of a silent WWOX transgene.

Delivery systems for pulmonary gene therapy

Delivery of therapeutic genes to the lungs is an attractive strategy to correct a variety of pulmonary dysfunctions such as cystic fibrosis, alpha-1 antitrypsin deficiency, pulmonary hypertension, asthma, and lung cancer. Different delivery routes such as intratracheal instillation, aerosol and intravenous injection have been utilized with varying degrees of efficiency. Both viral and non-viral vectors, with their respective strengths and weaknesses, have achieved significant levels of transgene expression in the lungs. However, the application of gene therapy for the treatment of pulmonary disease has been handicapped by various barriers to the delivery vectors such as serum proteins during intravenous delivery, and surfactant proteins and mucus in the airway lumen during topical application of therapeutic genes. Immune and cytokine responses against the delivery vehicle are also major problems encountered in pulmonary gene therapy. Despite these shortcomings much progress has been made to enhance the efficiency, as well as lower the toxicity of gene therapy vehicles in the treatment of pulmonary disorders such as cystic fibrosis, lung cancer and asthma.

Suicide gene therapy with an adenovirus expressing the fusion gene CD::UPRT in human glioblastomas: different sensitivities correlate with p53 status

BACKGROUND

Several gene therapy strategies have been designed for cancer treatment. Intra-tumoral injection of adenoviruses expressing pro-drug-converting enzymes is one such strategy. Although the efficacy of these therapies was tested in animal models, little work has been devoted to the determination of critical variables for success. In this work, we aimed at better understanding variables that affect the cytosine deaminase::uracil phosphoribosyl transferase (CD::UPRT)-based strategy in two human glioblastomas.

METHODS

We have constructed two adenoviruses expressing either CD or the fusion protein CD::UPRT. We have tested their anti-tumor activity in combination with 5-fluorocytosine (5-FC) in the glioblastoma cell lines U87 and U251, which are p53-wt and p53-deficient, respectively. Anti-tumor activity has also been investigated in spheroid structures.

RESULTS

The superiority of CD::UPRT over CD was confirmed in both glioblastoma cells. We found that the pro-drug concentration required for anti-tumor activity was 9-fold higher in U251 than in U87, while multiplicity of infection (MOI) as low as 6 was sufficient to achieve 50% killing. Bystander activity was observed with as few as 2 and 6% transduced cells for U87 and U251, respectively. Differences in sensitivity between U87 and U251 were not due to differences in transduction, transgene expression, or intercellular transport, but were related to 5-FU sensitivity and p53 status. Also, it is noteworthy that, in contrast to U87, U251 spheroids barely responded to the treatment, whereas their monolayer counterparts were very sensitive.

CONCLUSIONS

Our study has shown that p53 status is important for CD::UPRT/5-FC treatment. Moreover, this study demonstrated that the three-dimensional spheroid model is a more stringent in vitro model for suicide gene therapy evaluation than are monolayer cultures.

Gene therapy strategies to improve the effectiveness of cancer radiotherapy

Having the ability to alter the genetic makeup of a cancer cell by gene transfer is a potentially powerful strategy for treating human cancer. However, a low efficiency of gene delivery in vivo and poor tumour specificity has prevented the widespread implementation of this technology in the clinic. Despite these formidable obstacles, the first successful application of gene therapy in the treatment of cancer may occur when it is combined with local modalities such as radiation therapy. A small number of gene therapy strategies have been evaluated in clinical trials in combination with external beam radiation therapy. The combined therapy has been well-tolerated and has not exacerbated the side effects of radiation therapy. Gene transfer and tumour cell destruction has been demonstrated in vivo. Although the results await confirmation in larger, prospective Phase III trials, there is suggestive evidence that the combined therapies may be demonstrating better than expected antitumour activity. Our vast knowledge of the molecular defects that drive the cancer process, coupled with our expanding understanding of the genes responsible for tumour cell radioresistance, have spawned the development of rational, targeted gene therapies designed to increase tumour cell radiosensitivity. Here, the results of the clinical trials conducted so far will be reviewed, followed by a description of new approaches under development at present.

Replacement and Suicide Gene Therapy for Targeted Treatment of Lung Cancer

Lung cancer is the leading cause of cancer-related death in the developed world; consequently, novel therapeutic strategies are in high demand. A major problem with the present treatment modalities is the lack of tumor specificity giving rise to dose-limiting toxicity and side effects. Gene therapy constitutes an experimental approach gaining increased attention as a putative future cancer therapeutic strategy. Using this strategy, cancer cytotoxicity can be obtained by replacing mutated genes with functional analogues or introducing a suicide gene into the malignant cells. Insight into the molecular biology of cancer cells has identified a number of regulatory gene sequences, which can be used to selectively activate the therapeutic gene specifically in cancer cells, thereby reducing nonspecific toxicity. Although further improvements are necessary, recent encouraging results have shown promise for future clinical application of gene therapy. This article presents an update on the experimental and clinical results obtained within the field of lung cancer gene therapy, concentrating on strategies to specifically activate expression of the therapeutic gene in cancer cells. Furthermore, status of the development of delivery vector constructs for lung cancer gene therapy will be presented.

Identification of STAG1 as a key mediator of a p53-dependent apoptotic pathway

A mutant version of p53 (p53-121F), in which phenylalanine replaces the 121st serine residue, can induce apoptosis more effectively than wild-type p53 (wt-p53). In view of this observation, we considered that one or more apoptosis-related p53-target genes might be preferentially induced by p53-121F. We carried out cDNA microarray analysis to identify such genes, using mRNAs isolated from LS174T colon-cancer cells infected by adenovirus vectors containing either p53-121F (Ad-p53-121F) or wt-p53 (Ad-p53). The STAG1 gene was one of the transcripts showing higher expression levels in cells infected with Ad-p53-121F as opposed to Ad-wtp53. The encoded product appears to contain a transmembrane domain, and binding motifs for SH3 and WW. In two other cancer cell lines, the expression of STAG1 mRNA was induced in response to various genotoxic stresses in a p53-dependent manner; moreover, enforced expression of STAG1 led to apoptosis in several additional cancer cell lines. Suppression of endogenous STAG1 using the RNA-interference method reduced the apoptotic response, whether induced by Ad-p53-121F or Ad-p53. These results suggest that STAG1, a novel transcriptional target for p53, mediates p53-dependent apoptosis, and might be a good candidate for next-generation gene therapy.

Cooperative effect of adenoviral p53 gene therapy and standard chemotherapy in ovarian cancer cells independent of the endogenous p53 status

Clinical adenoviral p53 gene therapy has been shown by us and others to inhibit tumor growth of ovarian cancer with endogenous mutant p53. This study was designed to test the cooperative antitumor effect of standard combination chemotherapy using paclitaxel and carboplatin together with adenoviral p53 gene transfer in the presence of wild-type and mutant p53. Seven ovarian cancer cell lines with mutant p53 and seven ovarian cancer cell lines with wild-type p53 were tested. An E1-deleted adenovirus type 5 expressing p53 (ACNp53) was used for p53 gene transfer. p53 gene transfer at 50% transduction efficiency significantly reduced IC50 of carboplatin chemotherapy up to 49-fold, of paclitaxel chemotherapy up to six-fold, and of paclitaxel/carboplatin chemotherapy up to 19-fold in the wild-type p53 cell line OV-MZ-5. Synergism between ACNp53 and chemotherapy calculated by median-effect analysis was found at low drug concentrations in all cell lines independent of the p53 mutational status. In conclusion, adenoviral p53 gene transfer significantly increased the sensitivity of ovarian tumor cells to paclitaxel, to carboplatin and/or to the combination of both.

Endocrine aspects of cancer gene therapy

The field of cancer gene therapy is in continuous expansion, and technology is quickly moving ahead as far as gene targeting and regulation of gene expression are concerned. This review focuses on the endocrine aspects of gene therapy, including the possibility to exploit hormone and hormone receptor functions for regulating therapeutic gene expression, the use of endocrine-specific genes as new therapeutic tools, the effects of viral vector delivery and transgene expression on the endocrine system, and the endocrine response to viral vector delivery. Present ethical concerns of gene therapy and the risk of germ cell transduction are also discussed, along with potential lines of innovation to improve cell and gene targeting.

Clinical trials of adenoviruses in brain tumors: a review of Ad-p53 and oncolytic adenoviruses

Adenoviruses have been critical in the development of the molecular approaches to brain tumors. They have been engineered to function as vectors for delivering therapeutic genes in gene therapy strategies, and as direct cytotoxic agents in oncolytic viral therapies. This review outlines the uses of adenoviruses in brain tumor therapy by examining clinical trials of adenovirus-mediated p53 gene therapy and by reviewing the application of two conditionally replicative adenoviruses (CRAds) ONYX-015 and Delta 24 in brain tumors. The potential clinical use of CRAds that deliver trangenes, particularly p53, is also discussed.

Adenovirus-mediated p53AIP1 gene transfer as a new strategy for treatment of p53-resistant tumors

The p53AIP1 gene, which we recently identified as a novel p53-target, mediates p53-dependent apoptosis. We evaluated the effects of adenovirus-mediated introduction of p53AIP1 (Ad-p53AIP1) on 30 human cancer-cell lines in vitro, and two cell lines in vivo, in comparison with the effects of p53 (Ad-p53). In 20 of the 30 cell lines, p53AIP1-induced apoptosis was observed, and in 12 of these p53AIP1-sensitive cancer cell lines, the apoptotic effects of p53AIP1 were greater than those of p53 itself. Cancers with wild-type p53, which were thought to be p53-resistant, were likely to be sensitive to p53AIP1-induced apoptosis. p53-resistant cancers such as LS174T (p53 +/+) and A549 (p53 +/+), in which no increase of p53AIP1 mRNA expression was observed when Ad-p53 was introduced, were killed effectively by Ad-p53AIP1. Furthermore, co-introduction of p53 and p53AIP1 had a synergistic effect on the induction of apoptosis, regardless of p53 status. Finally, adenovirus-mediated introduction of p53AIP1 suppressed tumor growth in vivo. These results suggested that p53AIP1 gene transfer might become a new strategy for the treatment of p53-resistant cancers.

Chemotherapy in advanced non-small-cell lung cancer: a look behind and ahead

Lung cancer is still the leading cause of cancer-related deaths in Western countries. The 5-year survival rate in 2002 remains dismal. In advanced disease, chemotherapy is the cornerstone of treatment, but a crucial step is whether the impact of chemotherapy in the management of this disease justifies either the toxicity on patients or the always-rising costs. A number of randomized trials demonstrated a prolonged survival for patients treated with chemotherapy compared with best supportive care. However, newer platinum-based combination regimens have failed to take a major step forward; chemotherapy alone has reached a plateau of activity that could be partially solved by integrating molecular-targeted strategies in clinical practice. Quality of life remains a key issue in clinical decisions for metastatic patients. New answers will come by encouraging all fit patients to join clinical trials.

Biodistribution and pharmacokinetics of aerosol and intravenously administered DNA-polyethyleneimine complexes: optimization of pulmonary delivery and retention

This report describes the time-dependent biodistribution of human p53 plasmid delivered in aerosol with polyethyleneimine in mice compared to the distribution of this material following intravenous injection. Area-under-the-curve values for p53 plasmid after inhalation were 2.8-fold greater than values after intravenous administration, despite the fact that the delivered aerosol dose was one-fifth the intravenous dose. After aerosol administration, pulmonary concentrations of p53 plasmid were high and other organs showed amounts not distinguishable from untreated control. High concentrations of p53 plasmid in the lungs remained with negligible reduction for at least 24 h. Shortly after intravenous injection, organs exhibited the following relative levels of exogenously administered p53: liver > spleen > blood > or = lungs > heart > kidney. These results demonstrate effective pulmonary delivery of DNA in complex with PEI by aerosol, without significant systemic dissemination. In contrast, intravenous administration caused a prompt systemic distribution of DNA with a shorter half-life of the administered gene in the lungs.

Apoptotic genes in cancer therapy

Induction of apoptosis in malignant cells is a major goal of cancer therapy in general and of certain cancer gene therapy strategies in particular. Numerous apoptosis-regulating genes have been evaluated for this purpose. Besides the most prominent p53 gene others include p16, p21, p27, E2F genes, FHIT, PTEN and CASPASE genes. Recently, the potential for therapy of an adenoviral gene, E1A, known for a long time for its apoptosis-inducing activity, has been discovered. In experimental settings, these genes have proven their tumor-suppressive and apoptosis-inducing activity. Clinical trials are currently being performed with selected genes. By far the most studies transfer the p53 gene using retro- or adenoviral vectors. Disease stabilization or other benefits were observed in a limited number of patients when p53 was applied alone or in combination with cytotoxic drugs. A second proapoptotic gene that has entered clinical trials is adenovirus E1A. Here, too, disease stabilization as well as/or local regression in one case have been demonstrated in selected patients. In all cases, side effects were tolerable. To further improve E1A as a therapeutic transgene, we have deleted transforming domains from the adenovirus 5 and 12 13S cDNAs. Mutants were derived which had completely lost their transforming activity in combination with the E1B oncogene but retained a pronounced tumor-suppressive activity. Cells transduced with these constructs showed a highly reduced ability to grow in soft agar, and tumor growth in nude mice could be substantially suppressed. Outgrowing tumors had lost E1A expression when analyzed in Western blots. These E1A constructs may represent valuable tools for cancer gene therapy in the future.

Restoring apoptosis as a strategy for cancer gene therapy: focus on p53 and mda-7

Understanding the molecular and genetic determinants of cancer will provide unique opportunities for developing rational and effective therapies. Malignant cells are frequently resistant to chemotherapy and radiation induced programmed cell death (apoptosis). This resistance can occur by mutations in the tumor suppressor gene p53. Strategies designed to replace this defective tumor suppressor protein, as well as forced expression of a novel cancer specific apoptosis inducing gene, melanoma differentiation associated gene-7 (mda-7), offer promise for restoring apoptosis in tumor cells. Conditional-replicating viruses that selectively induce cytolysis in tumor cells provides an additional means of targeting cancer cells for destruction. Although these approaches represent works in progress, future refinements will in all likelihood result in the next generation of cancer therapies.

Gene Therapy Applications to Cancer Treatment

Over the past ten years significant advances have been made in the fields of gene therapy and tumour immunology, such that there now exists a considerable body of evidence validating the proof in the principle of gene therapy based cancer vaccines. While clinical benefit has so far been marginal, data from preclinical and early clinical trials of gene therapy combined with standard therapies are strongly suggestive of additional benefit. Many reasons have been proposed to explain the paucity of clinical responses to single agent vaccination strategies including the poor antigenicity of tumour cells and the development of tolerance through down-regulation of MHC, costimulatory, signal transduction, and other molecules essential for the generation of strong immune responses. In addition, there is now evidence from animal models that the growing tumour may actively inhibit the host immune response. Removal of the primary tumour prior to T cell transfer from the spleen of cancer bearing animals, led to effective tumour cell line specific immunity in the recipient mouse suggesting that there is an ongoing tumour-host interaction. This model also illustrates the potential difficulties of clinical vaccine trials in patients with advanced stage disease.

Recombinant adenovirus shedding after intratumoral gene transfer in lung cancer patients

We conducted two phase 1 trials of direct intratumoral injection of a recombinant E1E3-deleted adenovirus (AdR) encoding either the bacterial enzyme beta-galactosidase (Ad.RSVbetagal) or interleukin 2 (IL2, AdTG5327) into primary nonsmall-cell lung cancers of 21 patients. We report here virus shedding and the duration of virus expression in the tumor after intrabronchial injection of 10(7), 10(8) or 10(9) PFU of adenovirus. The infectious AdR and the viral DNA were detected in PBL, plasma, stool and aerodigestive samples in a dose-dependent manner, since cell cultures and PCRs were found to be positive mainly for samples from patients who received the highest AdR dose (10(9) PFU). We detected beta-galactosidase activity in the tumor biopsy samples of 66% of the patients, seemingly dose related, and only low levels of IL2 mRNA could be detected in tumor biopsy samples. E1 sequences were not detected by PCR in any of the PBL and bronchial samples collected after virus delivery, except in one patient. In this patient, E1 sequences were detected in PBL as well as in tumor biopsy samples collected at days 8, 30 and 60 and were correlated with longer beta-galactosidase expression in tumor samples. PBL tested before and after virus delivery contained both E1 sequences indicating that they did not result from replication-competent adenovirus (RCA) E1 sequences present in the inoculum. In addition, only on the day of the injection was Ad.RSVbetagal also detected in E1-positive PBL, indicating that virus replication in blood was very unlikely.

Laser fluorescence bronchoscopy for detection of fluorescent reporter genes in airway epithelia

Current methods for detecting successful gene transfer to airway epithelia involve obtaining a sample of the target tissue. This may affect the longevity of expression of the transgene under evaluation. We describe a laser fluorescence bronchoscopic system that can detect the expression of the fluorescent protein, green fluorescence protein (GFP), in the airway of monkeys that have been transfected with adenovirus, without the need for obtaining tissue. This technique will have applications in pre-clinical and clinical studies of gene transfer to airway epithelia and other surface epithelia accessible by endoscopy.