Phase I Study of Repeated Intraepithelial Delivery of Adenoviral p53 in Patients With Dysplastic Oral Leukoplakia

p21CIP/WAF1 saRNA inhibits proliferative vitreoretinopathy in a rabbit model

PURPOSE

Proliferative vitreoretinopathy (PVR) is a disease process resulting from proliferation of retinal pigment epithelial (RPE) cells in the vitreous and periretinal area, leading to periretinal membrane formation and traction and eventually to postoperative failure after vitreo-retinal surgery for primary rhegmatogenous retinal detachment (RRD). The present study was designed to test the therapeutic potential of a p21CIP/WAF1 (p21) inducing saRNA for PVR.

METHODS

A chemically modified p21 saRNA (RAG1-40-53) was tested in cultured human RPE cells for p21 induction and for the inhibition of cell proliferation, migration and cell cycle progression. RAG1-40-53 was further conjugated to a cholesterol moiety and tested for pharmacokinetics and pharmacodynamics in rabbit eyes and for therapeutic effects after intravitreal administration in a rabbit PVR model established by injecting human RPE cells.

RESULTS

RAG1-40-53 (0.3 mg, 1 mg) significantly induced p21 expression in RPE cells and inhibited cell proliferation, the progression of cell cycle at the G0/G1 phase and TGF-β1 induced migration. After a single intravitreal injection into rabbit eyes, cholesterol-conjugated RAG1-40-53 exhibited sustained concentration in the vitreal humor beyond at least 8 days and prevented the progression of established PVR.

CONCLUSION

p21 saRNA could represent a novel therapeutics for PVR by exerting a antiproliferation and antimigration effect on RPE cells.

Recombinant Human Adenovirus-p53 Therapy for the Treatment of Oral Leukoplakia and Oral Squamous Cell Carcinoma: A Systematic Review

Background and Objectives: Oral cancer is the 6th most common cancer in the world and oral leukoplakia is an oral potentially malignant disorder that could develop into oral cancer. This systematic review focusses on randomized clinical trials for recombinant adenovirus p-53 (rAD-p53) therapy for the treatment of oral leukoplakia and cancer. Materials and Methods: We searched for research articles on various databases such as Pubmed/Medline, Embase, CNKI (China National Knowledge Infra-structure), Springerlink, cochrane and Web of sciences from 2003 to 2020. MeSH (Medical Subject Headings) terms were used for the search. Inclusion criteria included original research, randomized clinical trials and articles only in English language. Exclusion criteria were any articles that were not research articles, not randomized trials, non-human studies, etc. The articles were further graded on the Jadad scale. Results: 578 articles were assessed from various databases; only 3 articles were found to be appropriate for this review. Thus, meta-analysis was not performed because of heterogeneity and lack of data. In the three studies, whether rAD-p53 was used as a standalone therapy or with other therapies, there was a beneficial effect of the therapy. Furthermore, there were no serious adverse events and the only adverse events reported were fever, pain at the local injection site, flu-like symptoms and lowered WBC count. Conclusions: Thus, we can conclude that this therapy has a potential for beneficial therapeutic effects and further clinical trials with more patients need to be performed to get better understanding of the effect of rAD-p53 therapy, which probably will pave the way to its approval in other parts of the world.

Difficulties in the Prognostic Study of Oral Leukoplakia: Standardisation Proposal of Follow-Up Parameters

Oral leukoplakia is the most prevalent potentially malignant disorder of the oral cavity. To evaluate its potential for malignancy, appropriate documentation of the biological parameters is crucial, allowing the patients' progression to be assessed. We hypothesized a lack of standardization in the parameters employed for the prognostic study of oral leukoplakia; our aims were to determine the different parameters used for follow-up according to definition, importance, and frequency of use, and to provide a standardization proposal of follow-up research. We made a scoping review to identify papers with the keywords “leukoplakia,” “oral,” and “follow-up” published until June 2019 in English, Spanish and Portuguese literature through an online search in PUBMED, SCIELO, and SCOPUS databases. In total, 514 articles were initially identified, and fifty-nine publications were selected, of which 37 were retrospective. The reports included a total of 18,660 patients between 13 and 98 years old, with a mean age of 57.6 years. Tobacco and alcohol habits were positive for 77 and 37% of the patients, respectively. Our results showed that reported leukoplakias were predominantly located on buccal mucosa (40.4%), were homogeneous (60.8%), multiple (59.9%), smaller than 2 cm (74.4%) and histopathologically non-dysplastic (71%). The mean follow-up time was 55 months, with a 13% malignant transformation rate. The categorization and definition of multiple variables were notably diverse. Age, sex, habits (tobacco and alcohol), site, size, distribution, morphology, degree of dysplasia, and evolution were the chosen parameters for our proposal. The current study reflected the lack of consensus found in the literature regarding parameters for diagnosis or follow-up, impacting negatively on clinical and research results. standardization comprises an efficient way to facilitate the prognosis assessment of oral leukoplakia, being beneficial for clinical practice, and enabling better quality information to apply in research.

Applications of Virus Vector-Mediated Gene Therapy in China

Due to the increased safety and efficiency of virus vectors, virus vector-mediated gene therapy is now widely used for various diseases, including monogenic diseases, complex disorders, and infectious diseases. Recent gene therapy trials have shown significant therapeutic benefits, and Chinese researchers have contributed significantly to this progress. This review highlights disease applications and strategies for virus vector-mediated gene therapy in preclinical studies and clinical trials in China.

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.

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.

Overexpression p21WAF1/CIP1 in suppressing retinal pigment epithelial cells and progression of proliferative vitreoretinopathy via inhibition CDK2 and cyclin E

Background

P21 is one kind of cyclin-dependent kinase inhibitor that can prevent cells from going through the G1/S phase checkpoint and inhibit cell proliferation. Proliferative vitreoretinopathy (PVR) is a proliferative response in the eye. The aim of this study was to determine whether p21^Waf1/Cip1 (p21) suppresses the proliferation and migration of retinal pigment epithelial (RPE) cells in vitro and controls PVR development in vivo.

Methods

Cell cycle analyses and transwell assays were conducted to assess cell proliferation characteristics and the migration ability of RPE cells after transfection with p21. Western blot and reverse-transcription polymerase chain reaction technologies were used to detect the expression of p21, CDK₂ and cyclinE in RPE cells and rabbit retinal tissues. The impact of increasing p21 expression on PVR development was conducted by implantation of an adenovirus vector containing rabbit p21 (rAd-p21) in a PVR rabbit model. The prevalence of PVR and retinal detachment was determined by indirect ophthalmoscopy on days 3, 7, 14, and 21 after the injection of rAd-p21 into the vitreous. B scans and hematoxylin-eosin staining were employed to check rabbit retinas on day 21.

Results

Cell cycle analyses and transwell assays showed that p21 inhibited the proliferation and migration of RPE cells. Increased expression of p21 was detected in cultured RPE cells and rabbit retinas after transfection with the p21 gene, whereas levels of CDK₂ and cyclinE were decreased. The increase in p21 expression effectively suppressed the development of PVR in a rabbit model.

Conclusions

The increase in p21 expression in RPE cells not only inhibits the proliferation and migration of RPE cells in vitro, but also suppresses the development of PVR in vivo, which indicates its therapeutic potential in treating PVR.

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.

Chemotherapeutic compounds targeting the DNA double-strand break repair pathways: the good, the bad, and the promising

The repair of DNA double-strand breaks (DSBs) is a critical cellular mechanism that exists to ensure genomic stability. DNA DSBs are the most deleterious type of insult to a cell's genetic material and can lead to genomic instability, apoptosis, or senescence. Incorrectly repaired DNA DSBs have the potential to produce chromosomal translocations and genomic instability, potentially leading to cancer. The prevalence of DNA DSBs in cancer due to unregulated growth and errors in repair opens up a potential therapeutic window in the treatment of cancers. The cellular response to DNA DSBs is comprised of two pathways to ensure DNA breaks are repaired: homologous recombination and non-homologous end joining. Identifying chemotherapeutic compounds targeting proteins involved in these DNA repair pathways has shown promise as a cancer therapy for patients, either as a monotherapy or in combination with genotoxic drugs. From the beginning, there have been a number of chemotherapeutic compounds that have yielded successful responses in the clinic, a number that have failed (CGK-733 and iniparib), and a number of promising targets for future studies identified. This review looks in detail at how the cell responds to these DNA DSBs and investigates the chemotherapeutic avenues that have been and are currently being explored to target this repair process.

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).

Chemoprevention of head and neck squamous cell carcinoma through inhibition of NF-κB signaling

Nuclear factor-kappa B (NF-κB) transcription factors regulate cellular processes such as inflammation and cell survival. The NF-κB pathway is often activated with development and progression of head and neck squamous cell carcinoma (HNSCC). As such, NF-κB represents an attractive target for chemoprevention. HNSCC involves progression of lesions from premalignant to malignant, providing a window of opportunity for intervention with chemopreventive agents. Appropriate chemopreventive agents should be inexpensive, nontoxic, and target important pathways involved in the development of HNSCC. Several such agents that inhibit the NF-κB pathway have been investigated in HNSCC. Retinoids have been studied most extensively but have shown limited potential in human trials. Epidermal growth factor receptor inhibitors and PI3K-mTOR inhibitors may benefit a subset of patients. Other agents such as green tea extract and curcumin are appealing because they are generally regarded as safe. In contrast, there is evidence that Vitamin E supplementation may actually increase mortality of cancer patients. Repurposed drugs such as cyclooxygenase (COX) inhibitors and antidiabetic drugs are an emerging area of interest. Future research to develop agents with lower toxicity and higher specificity for the NF-κB pathway, and to target these therapies to individual patient genetic signatures should help to increase the utility of chemoprevention in HSNCC.

p53-based therapeutics for head and neck squamous cell carcinoma

Inactivation of the tumor suppressor p53 is a pathogenetic event in the development of head and neck squamous cell carcinoma (HNSCC). In the absence of functional wildtype p53, HNSCC cells have increased resistance to standard chemotherapeutics and radiation. Numerous approaches to restore p53 function in cancer cells have been developed over the past several decades. This review article focuses on viral approaches to deliver wildtype p53 to HNSCC cells, a designer virus that selectively eliminates mutant p53 HNSCC cells, and chemical approaches to reactivate p53 function in HNSCC cells. These promising studies provide evidence that p53 therapeutics may prove useful alone or in combination with conventional chemotherapy and/or radiation for the management of HNSCC patients.

Selective biophysical interactions of surface modified nanoparticles with cancer cell lipids improve tumor targeting and gene therapy

Targeting gene- or drug-loaded nanoparticles (NPs) to tumors and ensuring their intratumoral retention after systemic administration remain key challenges to improving the efficacy of NP-based therapeutics. Here, we investigate a novel targeting approach that exploits changes in lipid metabolism and cell membrane biophysics that occur during malignancy. We hypothesized that modifications to the surface of NPs that preferentially increase their biophysical interaction with the membrane lipids of cancer cells will improve intratumoral retention and in vivo efficacy upon delivery of NPs loaded with a therapeutic gene. We have demonstrated that different surfactants, incorporated onto the NPs' surface, affect the biophysical interactions of NPs with the lipids of cancer cells and normal endothelial cells. NPs surface modified with didodecyldimethylammoniumbromide (DMAB) demonstrated greater interaction with cancer cell lipids, which was 6.7-fold greater than with unmodified NPs and 5.5-fold greater than with endothelial cell lipids. This correlated with increased uptake of DMAB-modified NPs with incubation time by cancer cells compared to other formulations of NPs and to uptake by endothelial cells. Upon systemic injection, DMAB-NPs demonstrated a 4.6-fold increase in tumor accumulation compared to unmodified NPs which also correlated to improved efficacy of p53 gene therapy. Characterization of the biophysical interactions between NPs and lipid membranes of tumors or other diseased tissues/organs may hold promise for engineering targeted delivery of therapeutics.

Inhibition of tumor angiogenesis and growth by nanoparticle-mediated p53 gene therapy in mice

Mutation of the p53 tumor suppressor gene, the most common genetic alteration in human cancers, results in more aggressive disease and increased resistance to conventional therapies. Aggressiveness may be related to the increased angiogenic activity of cancer cells containing mutant p53. To restore wild-type p53 function in cancer cells, we developed polymeric nanoparticles (NPs) for p53 gene delivery. Previous in vitro and in vivo studies demonstrated the ability of these NPs to provide sustained intracellular release of DNA, thus sustained gene transfection and decreased tumor cell proliferation. We investigated in vivo mechanisms involved in NP-mediated p53 tumor inhibition, with focus on angiogenesis. We hypothesize that sustained p53 gene delivery will help decrease tumor angiogenic activity and thus reduce tumor growth and improve animal survival. Xenografts of p53 mutant tumors were treated with a single intratumoral injection of p53NPs. We observed intratumoral p53 gene expression corresponding to tumor growth inhibition, over 5 weeks. Treated tumors showed upregulation of thrombospondin-1, a potent antiangiogenic factor, and a decrease in microvessel density vs. controls (saline, p53 DNA alone, and control NPs). Greater levels of apoptosis were also observed in p53NP-treated tumors. Overall, this led to significantly improved survival in p53NP-treated animals. NP-mediated p53 gene delivery slowed cancer progression and improved survival in an in vivo cancer model. One mechanism by which this is accomplished is disruption of tumor angiogenesis. We conclude that the NP-mediated sustained tumor p53 gene therapy can effectively be used for tumor growth inhibition.

New developments and opportunities in oral mucosal drug delivery for local and systemic disease

The oral mucosa's accessibility, excellent blood supply, by-pass of hepatic first-pass metabolism, rapid repair and permeability profile make it an attractive site for local and systemic drug delivery. Technological advances in mucoadhesives, sustained drug release, permeability enhancers and drug delivery vectors are increasing the efficient delivery of drugs to treat oral and systemic diseases. When treating oral diseases, these advances result in enhanced therapeutic efficacy, reduced drug wastage and the prospect of using biological agents such as genes, peptides and antibodies. These technologies are also increasing the repertoire of drugs that can be delivered across the oral mucosa to treat systemic diseases. Trans-mucosal delivery is now a favoured route for non-parenteral administration of emergency drugs and agents where a rapid onset of action is required. Furthermore, advances in drug delivery technology are bringing forward the likelihood of transmucosal systemic delivery of biological agents.

GUCY2C-targeted cancer immunotherapy: past, present and future

For the last decade, we have focused on guanylyl cyclase C (GUCY2C) as a potentially ideal target antigen for colorectal cancer immunotherapy. GUCY2C is expressed only in intestinal epithelial cells and by nearly 100% of colorectal cancers. We have developed and tested a recombinant adenoviral vector possessing GUCY2C (Ad5-GUCY2C) as a candidate vaccine for colorectal cancer patients. Murine studies have revealed that this vaccine is safe and effective against GUCY2C-expressing targets, and Ad5-GUCY2C is poised for phase I clinical testing in colorectal cancer patients with minimal residual disease. Moreover, we are developing second-generation GUCY2C-targeted therapeutics, including the use of chimeric antigen receptor (CAR)-expressing T cells, for treatment of patients with advanced colorectal cancer for whom Ad5-GUCY2C immunization is not appropriate. Thus, a family of GUCY2C-targeted immunotherapeutics may bridge the gap in effective treatments for the 500,000 patients worldwide who die annually from colorectal cancer.

Optimizing therapeutic efficacy of chemopreventive agents: A critical review of delivery strategies in oral cancer chemoprevention clinical trials

Due to its characterized progression from recognized premalignant oral epithelial changes (i.e., oral epithelial dysplasia) to invasive cancer, oral squamous cell carcinoma represents an optimal disease for chemopreventive intervention prior to malignant transformation. The primary goal of oral cancer chemoprevention is to reverse, suppress, or inhibit the progression of premalignant lesions to cancer. Over the last several decades, numerous oral cancer chemoprevention clinical trials have assessed the therapeutic efficacy of diverse chemopreventive agents. The standard of care for more advanced oral dysplastic lesions entails surgical excision and close clinical follow-up due to the potential (~33%) for local recurrence at a similar or more advanced histological stage. The purpose of this review was to identify prominent oral cancer chemoprevention clinical trials, assess their overall therapeutic efficacy, and delineate effects of local versus systemic drug administration. In addition, these compiled clinical trial data present concepts for consideration in the design and conduction of future clinical trials.

Multiple treatment cycles of liposome-encapsulated adenoviral RIP-TK gene therapy effectively ablate human pancreatic cancer cells in SCID mice

BACKGROUND

Adenoviral gene therapy has been applied widely for cancer therapy; however, transient gene expression as result of humoral immunoneutralization response to adenovirus limits its effect. The purpose of this study is to determine whether DOTAP:cholesterol liposome could shield adenovirus from neutralizing antibody and permit the use of multiple cycles of intravenous liposome encapsulated serotype 5 adenoviral rat insulin promoter directed thymidine kinase (L-A-5-RIP-TK) with ganciclovir (GCV) to enhance its effect.

METHODS

The effect of multiple cycles of systemic L-A-5-RIP-TK/GCV therapy was evaluated in grouped PANC-1 SCID mice treated with different numbers of cycles. Humoral immune response to A-5-RIP-TK or L-A-5-RIP-TK was assessed using C57/B6J mice challenged with adenovirus or liposome adenovirus complex.

RESULTS

The minimal residual tumor burden (3.2 ± 0.6 mm(3)) and greatest survival time (153.0 ± 6 days) were obtained in the mice receiving 4 and 3 cycles of therapy, respectively. Toxicity to islet cells associated with RIP-TK/GCV therapy was observed after 4 cycles. DOTAP:chol-encapsulated adenovectors were able to protect adenovectors from the neutralization of high titer of anti-adenoviral antibodies induced by itself.

CONCLUSION

Multiple treatment cycles of L-A-5-RIP-TK/GCV ablate human PANC-1 cells effectively in SCID mice; however, the mice become diabetic and have substantial mortality after the 4th cycle. Liposome-encapsulated adenovirus is functionally resistant to the neutralizing effects of anti-adenoviral antibodies, suggesting feasibility of multiple cycles of therapy. Liposome encapsulation of the adenovirus may be a promising strategy for repeated delivery of systemic adenoviral gene therapy.

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.

Role of p53 mutation in the effect of boron neutron capture therapy on oral squamous cell carcinoma

Background

Boron neutron capture therapy (BNCT) is a selective radiotherapy, being effective for the treatment of even advanced malignancies in head and neck regions as well as brain tumors and skin melanomas. To clarify the role of p53 gene, the effect of BNCT on oral squamous cell carcinoma (SCC) cells showing either wild- (SAS/neo) or mutant-type (SAS/mp53) p53 was examined.

Methods

Cells were exposed to neutron beams in the presence of boronophenylalanine (BPA) at Kyoto University Research Reactor. Treated cells were monitored for modulations in colony formation, proliferation, cell cycle, and expression of cell cycle-associated proteins.

Results

When SAS/neo and SAS/mp53 cells were subjected to BNCT, more suppressive effects on colony formation and cell viability were observed in SAS/neo compared with SAS/mp53 cells. Cell cycle arrest at the G1 checkpoint was observed in SAS/neo, but not in SAS/mp53. Apoptotic cells increased from 6 h after BNCT in SAS/neo and 48 h in SAS/mp53 cells. The expression of p21 was induced in SAS/neo only, but G2 arrest-associated proteins including Wee1, cdc2, and cyclin B1 were altered in both cell lines.

Conclusion

These results indicate that oral SCC cells with mutant-type are more resistant to BNCT than those with wild-type p53, and that the lack of G1 arrest and related apoptosis may contribute to the resistance. At a physical dose affecting the cell cycle, BNCT inhibits oral SCC cells in p53-dependent and -independent manners.