Control of cervicovaginal HPV-16 E7-expressing tumors by the combination of therapeutic HPV vaccination and vascular disrupting agents

Abstract Antigen-specific immunotherapy and vascular disrupting agents, such as 5,6-dimethylxanthenone-4-acetic acid (DMXAA), have emerged as attractive approaches for the treatment of cancers. In the current study, we tested the combination of DMXAA treatment with therapeutic human papillomavirus type 16 (HPV-16) E7 peptide-based vaccination for their ability to generate E7-specific CD8+ T-cell immune responses, as well as their ability to control E7-expressing tumors in a subcutaneous and a cervicovaginal tumor model. We found that the combination of DMXAA treatment with E7 long peptide (amino acids 43-62) vaccination mixed with polyriboinosinic:polyribocytidylic generated significantly stronger E7-specific CD8+ T-cell immune responses and antitumor effects compared with treatment with DMXAA alone or HPV peptide vaccination alone in the subcutaneous model. Additionally, we found that the DMXAA-mediated enhancement of E7-specific CD8+ T-cell immune responses generated by the therapeutic HPV peptide-based vaccine was dependent on the timing of administration of DMXAA. Treatment with DMXAA in tumor-bearing mice was also shown to lead to increased dendritic cell maturation and increased production of inflammatory cytokines in the tumor. Furthermore, we observed that the combination of DMXAA with HPV-16 E7 peptide vaccination generated a significant enhancement in the antitumor effects in the cervicovaginal TC-1 tumor growth model, which closely resembles the tumor microenvironment of cervical cancer. Taken together, our data demonstrated that administration of the vascular disrupting agent, DMXAA, enhances therapeutic HPV vaccine-induced cytotoxic T-lymphocyte responses and antitumor effects against E7-expressing tumors in two different locations. Our study has significant implications for future clinical translation.

Vascular disrupting agent DMXAA enhances the antitumor effects generated by therapeutic HPV DNA vaccines

Antigen-specific immunotherapy using DNA vaccines has emerged as an attractive approach for the control of tumors. Another novel cancer therapy involves the employment of the vascular disrupting agent, 5,6-dimethylxanthenone-4-acetic acid (DMXAA). In the current study, we aimed to test the combination of DMXAA treatment with human papillomavirus type 16 (HPV-16) E7 DNA vaccination to enhance the antitumor effects and E7-specific CD8+ T cell immune responses in treated mice. We determined that treatment with DMXAA generates significant therapeutic effects against TC-1 tumors but does not enhance the antigen-specific immune responses in tumor bearing mice. We then found that combination of DMXAA treatment with E7 DNA vaccination generates potent antitumor effects and E7-specific CD8+ T cell immune responses in the splenocytes of tumor bearing mice. Furthermore, the DMXAA-mediated enhancement or suppression of E7-specific CD8+ T cell immune responses generated by CRT/E7 DNA vaccination was found to be dependent on the time of administration of DMXAA and was also applicable to other antigen-specific vaccines. In addition, we determined that inducible nitric oxide synthase (iNOS) plays a role in the immune suppression caused by DMXAA administration before DNA vaccination. Our study has significant implications for future clinical translation.

Characterization of immortalized mesenchymal stem cells derived from foetal porcine pancreas

Islet replacement therapy is limited by shortage of donor islet cells. Usage of islet cells derived from porcine pancreatic stem cells (PSCs) is currently viewed as the most promising alternative for human islet transplantation. However, PSCs are rare and have a finite proliferative lifespan. In this study, we isolated and established an immortalized mesenchymal stem cell (MSC) line derived from foetal porcine pancreas, by transfecting human telomerase reverse transcriptase (hTERT) and called these immortalized pancreatic mesenchymal stem cells (iPMSCs). The iPMSCs have been cultured for more than 80 passages and have capacity to differentiate into neurons, cardiomyocytes, germ cells and islet-like cells, analysed by morphology, RT-PCR, western blotting, immunofluorescence, immunocytochemistry and transplantation assay. Islets derived from iPMSCs reversed hyperglycaemia in streptozotocin-induced diabetic mice and secreted insulin and C-peptide in vitro. These results demonstrated that iPMSCs might provide unlimited resources for islet replacement therapy and models for functional cell differentiation.

In vivo microRNA-155 expression influences antigen-specific T cell-mediated immune responses generated by DNA vaccination

Background

MicroRNA (miRNA) molecules are potent mediators of post-transcriptional gene silencing that are emerging to be critical in the regulation of innate and adaptive immunity.

Results

Here we report that miR-155--an oncogenic miRNA with important function in the mammalian immune system--is induced in dendritic cells (DCs) upon maturation and potentially attenuates their ability to activate T cells. Biolistic epidermal transfection with DNA encoding miR-155 suppressed the induction of antigen-specific T cell-mediated immunity, whereas reduction of endogenous miR-155 by a partially complementary antisense sequence reversed this effect. Because DCs represent a significant component of epidermal tissue and are among the most potent of antigen-presenting cells, the inhibitory actions of miR-155 could be mediated through this subset of cells.

Conclusions

These results suggest that miR-155 may repress the expression of key molecules involved in lymph node migration, antigen presentation, or T cell activation in DCs, and thus forms part of a negative regulatory pathway that dampens the generation of T cell-mediated immune responses. Modulation of miR-155 expression in epidermis therefore represents a potentially promising form of gene therapy for the control of diseases ranging from autoimmunity to cancer and viral infection.

Innovative DNA vaccine for human papillomavirus (HPV)-associated head and neck cancer

Human papillomavirus (HPV), particularly type 16, has been associated with a subset of head and neck cancers. The viral-encoded oncogenic proteins E6 and E7 represent ideal targets for immunotherapy against HPV-associated head and neck cancers. DNA vaccines have emerged as attractive approaches for immunotherapy due to its simplicity, safety, and ease of preparation. Intradermal administration of DNA vaccine via gene gun represents an efficient method to deliver DNA directly into dendritic cells for priming antigen-specific T cells. We have previously shown that a DNA vaccine encoding an invariant chain (Ii), in which the class II-associated Ii peptide (CLIP) region has been replaced by a Pan-DR-epitope (PADRE) sequence to form Ii-PADRE, is capable of generating PADRE-specific CD4+ T cells in vaccinated mice. In the current study, we hypothesize a DNA vaccine encoding Ii-PADRE linked to E6 (Ii-PADRE-E6) will further enhance E6-specific CD8+ T cell immune responses through PADRE-specific CD4+ T helper cells. We found that mice vaccinated with Ii-PADRE-E6 DNA generated comparable levels of PADRE-specific CD4+ T cell immune responses as well as significantly stronger E6-specific CD8+ T cell immune responses and antitumor effects against the lethal challenge of E6-expressing tumor compared to mice vaccinated with Ii-E6 DNA. Taken together, our data indicates that vaccination with Ii-E6 DNA with PADRE replacing the CLIP region is capable of enhancing the E6-specific CD8+ T cell immune response generated by the Ii-E6 DNA. Thus, Ii-PADRE-E6 represents a novel DNA vaccine for the treatment of HPV-associated head and neck cancer and other HPV-associated malignancies.

Characterization of human papillomavirus type 11-specific immune responses in a preclinical model

OBJECTIVES/HYPOTHESIS

Human papillomavirus (HPV) types 6 and 11 are associated with recurrent respiratory papillomatosis (RRP). Although a prophylactic vaccine has been developed that protects against HPV infection, a therapeutic vaccine is still needed for those patients infected with and/or suffering from persistent disease. Therefore, we developed a novel, therapeutic DNA vaccine targeting HPV-11 and characterized the in vivo immunologic responses generated against HPV-11 E6 and E7 after DNA vaccination in a preclinical model.

METHODS

We generated a DNA vaccine that encodes the HPV-11 E6 and E7 genes in a pcDNA3 backbone plasmid. We then vaccinated C57BL/6 mice with the pcDNA3-HPV11-E6E7 DNA plasmid. Splenocytes were harvested from these vaccinated animals and were incubated with overlapping peptides spanning either the HPV-11 E6 or E7 protein. The frequency of interferon-gamma-releasing CD8(+) T cell responses was then analyzed by flow cytometry.

RESULTS

Vaccinated mice with the HPV11-E6E7 DNA generated strong CD8(+) T cell responses against the E6(aa44-51) peptide. We determined that the epitope is presented by the MHC class I H2-K(b) molecule. No significant E7 peptide-specific T cell responses were observed.

CONCLUSIONS

We developed a novel DNA vaccine that targets the E6 gene of HPV-11. Characterization of the immunologic responses elicited by this DNA vaccine reveals that the E6(aa44-51) peptide contains the most immunogenic region for the HPV-11 viral type. Knowledge of this specific T cell epitope and generation of a RRP preclinical model will allow for the development and evaluation of novel vaccine strategies targeting the RRP patient population.

Vascular Disrupting Agent, DMXAA, Enhances Therapeutic HPV Vaccine-Induced CTL responses and Antitumor Effects (101.37)

Antigen-specific immunotherapy has emerged as an attractive approach for the treatment of cancers. Another novel cancer therapy involves the employment of the vascular disrupting agent, 5,6-dimethylxanthenone-4-acetic acid (DMXAA). In the current study, we aimed to test the combination of DMXAA treatment with human papillomavirus type 16 (HPV-16) E7 peptide-based vaccination for their ability to enhance the E7-specific CD8+ T cell immune responses and antitumor effects in treated mice. We found that the combination of DMXAA treatment with E7 long peptide (aa43-62) vaccination mixed with polyI:C generates potent antitumor effects and E7-specific CD8+ T cell immune responses in the splenocytes and tumor-infiltrating lymphocytes (TILs) of tumor bearing mice. Furthermore, we found that the DMXAA-mediated enhancement of E7-specific CD8+ T cell immune responses was dependent on the timing of administration of DMXAA and was also applicable to other antigen-specific vaccines. We further tested the combination of DMXAA with E7 peptide vaccination in a vaginal TC-1 tumor growth model and observed a significant enhancement in the antitumor effects in treated mice. Taken together, our data demonstrated that administration of the vascular disrupting agent, DMXAA, enhances therapeutic HPV vaccine-induced CTL responses and antitumor effects against E7-expressing tumors in two different locations. Our study has significant implications for future clinical translation.

Pluripotency factors Lin28 and Oct4 identify a sub-population of stem cell-like cells in ovarian cancer

Lin28 and Oct4 are highly expressed in human embryonic stem (ES) cells and, along with two other stem cell marker proteins (Nanog and Sox2), together can convert human somatic cells to pluripotency. As an RNA-binding protein, Lin28 acts to stimulate the translation of a specific subset of mRNAs, and to inhibit the biogenesis of a group of microRNAs. Oct4 is a transcription factor essential for the maintenance of pluripotency and survival of ES cells. In this study, we report that a sub-population of epithelial ovarian cancer (EOC) cells co-expresses Lin28 and Oct4 as demonstrated in the analyses of both cell lines and patient tumor samples. We also observe that the combined expression of these proteins in tumor samples is correlated with advanced tumor grade. Intriguingly, when the expression of these two proteins is repressed in the same cells using RNA interference, there is significant reduction in cell growth and survival. We thus propose that Lin28 and Oct4 may have important roles in the initiation and/or progression of EOC, and consequently may serve as important molecular diagnostics and/or therapeutic targets for the development of novel treatment strategies in EOC patients.

Prevalence of erosive esophagitis and Barrett's esophagus in the adult Chinese population

BACKGROUND AND STUDY AIM

The aim of this study was to determine the prevalence, characteristics, and risk factors of erosive esophagitis and Barrett's esophagus in an adult Chinese population without gastroesophageal reflux symptoms.

PATIENTS AND METHODS

Between March 2006 and February 2007, consecutive individuals aged between 18 and 75 years, who underwent routine upper endoscopy as part of their regular medical examination were recruited. Demographic and medical information were collected. Erosive esophagitis was defined endoscopically as visible breaks of the distal esophageal mucosa. Barrett's esophagus was diagnosed endoscopically and confirmed histologically. "Silent GERD" was defined when erosive esophagitis and/or Barrett's esophagus were present in an individual without reflux symptoms.

RESULTS

Among the 2580 individuals included, erosive esophagitis and Barrett's esophagus were found in 4.3 % (n = 110) and 1.0 % (n = 27), respectively. In individuals with erosive esophagitis and Barrett's esophagus, 33.6 % and 40.7 %, respectively, were asymptomatic. Thus, the prevalence of erosive esophagitis and Barrett's esophagus in individuals without GERS was 1.6 % and 0.5 %, respectively, giving an overall prevalence of silent GERD of 2.0 % (46 / 2270). Multivariate analysis identified that male sex (odds ratio [OR] = 2.87, 95 % confidence interval [CI] 1.24 - 6.66; P = 0.014), hiatus hernia (OR = 9.68, 95 %CI 5.00 - 17.95; P < 0.001), and alcohol consumption (OR = 3.17, 95 %CI 1.44 - 6.97; P = 0.004) were positively associated with erosive esophagitis, whereas Helicobacter Pylori infection (OR = 0.37, 95 %CI 0.14 - 0.98; P = 0.046) was negatively associated with erosive esophagitis. Alcohol consumption (OR = 5.32, 95 %CI 1.55 - 13.33; P = 0.008) was positively associated with Barrett's esophagus in asymptomatic individuals.

CONCLUSION

In this cohort of the adult Chinese population without reflux symptoms, the prevalence of erosive esophagitis and Barrett's esophagus is 1.6 % and 0.5 %, respectively, with an overall prevalence of silent GERD of 2.0 %. Male sex, hiatus hernia, and alcohol consumption are positively associated with erosive esophagitis, whereas a negative association exists for H. pylori infection. Alcohol consumption is positively associated with Barrett's esophagus.

Response of aged parkinsonian monkeys to in vivo gene transfer of GDNF

This study assessed the potential for functional and anatomical recovery of the diseased aged primate nigrostriatal system, in response to trophic factor gene transfer. Aged rhesus monkeys received a single intracarotid infusion of MPTP, followed one week later by MRI-guided stereotaxic intrastriatal and intranigral injections of lentiviral vectors encoding for glial derived neurotrophic factor (lenti-GDNF) or beta-galactosidase (lenti-LacZ). Functional analysis revealed that the lenti-GDNF, but not lenti-LacZ treated monkeys displayed behavioral improvements that were associated with increased fluorodopa uptake in the striatum ipsilateral to lenti-GDNF treatment. GDNF ELISA of striatal brain samples confirmed increased GDNF expression in lenti-GDNF treated aged animals that correlated with functional improvements and preserved nigrostriatal dopaminergic markers. Our results indicate that the aged primate brain challenged by MPTP administration has the potential to respond to trophic factor delivery and that the degree of neuroprotection depends on GDNF levels.

Carbon nanotube reservoirs for self-healing materials

A novel nanoreservoir made of carbon nanotubes (CNTs) is proposed for realizing tougher and automated self-healing materials. The advantages of the approach are that CNTs have the potential to play the role of reinforcing elements prior to and after sealing a crack and that the number of voids is reduced after the material and the CNTs themselves are healed. The focus of this paper is on investigating the feasibility of using CNTs as a nanoreservoir by analyzing the dynamics of a fluid flowing out of a ruptured single-walled CNT (SWNT), where the fluid resembles an organic healing agent. With this in mind the escaping mechanism of organic molecules stored inside a cracked SWNT was investigated through a molecular dynamics study. The study shows that, when a SWNT wall suffers the formation of a crack, a certain amount of organic molecules, stored inside the SWNT, escape into space in a few picoseconds. This phenomenon is found to depend on the temperature and on the size of the cracks. The results of this study indicate that CNTs have the potential to be successfully used to realize the next generation of stronger, lighter and self-healing materials.

Increased frequencies of T helper type 17 cells in the peripheral blood of patients with acute myeloid leukaemia

T helper type 17 (Th17) cells, which represent a novel subset of CD4(+) T cells, play an active role in inflammatory and autoimmune diseases. Recent studies have also suggested that they have an impact on solid tumours. However, the nature of Th17 cells in haematological malignancies remains unknown. In this study, we investigated Th17 cell frequency and secretion of related cytokines in patients with acute myeloid leukaemia (AML). First, we found that Th17 cell frequencies were increased significantly in peripheral blood samples from untreated patients with AML, compared with those from healthy volunteers. Moreover, increased interleukin (IL)-17 concentrations accompanied the increased Th17 cell frequencies in these patients. These results suggest that Th17 cells may play a role in the pathogenesis of AML. Secondly, we found that the increased Th17 cell frequencies were reduced when patients achieved complete remission after chemotherapy, suggesting that measurement of Th17 cell frequencies may have clinical value in the evaluation of therapeutic effect. In addition, we found that IL-6 and transforming growth factor (TGF)-beta1 concentrations increased in the untreated patients and that IL-6 concentrations showed a positive correlation with the frequencies of Th17 cells, suggesting that IL-6 may play an important role in Th17 cell differentiation in patients with AML.

Abnormal striatal and thalamic dopamine neurotransmission: Genotype-related features of dystonia

OBJECTIVE

To determine whether changes in D(2) receptor availability are present in carriers of genetic mutations for primary dystonia.

METHODS

Manifesting and nonmanifesting carriers of the DYT1 and DYT6 dystonia mutations were scanned with [(11)C] raclopride (RAC) and PET. Measures of D(2) receptor availability in the caudate nucleus and putamen were determined using an automated region-of-interest approach. Values from mutation carriers and healthy controls were compared using analysis of variance to assess the effects of genotype and phenotype. Additionally, voxel-based whole brain searches were conducted to detect group differences in extrastriatal regions.

RESULTS

Significant reductions in caudate and putamen D(2) receptor availability were evident in both groups of mutation carriers relative to healthy controls (p < 0.001). The changes were greater in DYT6 relative to DYT1 carriers (-38.0 +/- 3.0% vs -15.0 +/- 3.0%, p < 0.001). By contrast, there was no significant difference between manifesting and nonmanifesting carriers of either genotype. Voxel-based analysis confirmed these findings and additionally revealed reduced RAC binding in the ventrolateral thalamus of both groups of mutation carriers. As in the striatum, the thalamic binding reductions were more pronounced in DYT6 carriers and were not influenced by the presence of clinical manifestations.

CONCLUSIONS

Reduced D(2) receptor availability in carriers of dystonia genes is compatible with dysfunction or loss of D(2)-bearing neurons, increased synaptic dopamine levels, or both. These changes, which may be present to different degrees in the DYT1 and DYT6 genotypes, are likely to represent susceptibility factors for the development of clinical manifestations in mutation carriers.

Combination of proteasome and HDAC inhibitors for uterine cervical cancer treatment

PURPOSE

Cervical cancer cells are addicted to the expression of the human papillomavirus (HPV) oncoproteins E6 and E7. The oncogencity of E6 is mediated in part by targeting p53 and PDZ-family tumor suppressor proteins for rapid proteasomal degradation, whereas the E7 oncoprotein acts in part by coopting histone deacetylases (HDAC)1/2. Here, we examine the hypothesis that inhibition of proteasome function and HDAC activity would synergistically and specifically trigger cervical cancer cell death by the interruption of E6 and E7 signaling.

EXPERIMENTAL DESIGN

The sensitivity and molecular responses of keratinocytes and HPV-positive and HPV-negative cervical cancer cells and xenografts to combinations of proteasome and HDAC inhibitors were tested. The expression of HDAC1/HDAC2 in situ was examined in cervical cancer, its precursors, and normal epithelium.

RESULTS

Cervical cancer cell lines exhibit greater sensitivity to proteasome inhibitors than do HPV-negative cervical cancers or primary human keratinocytes. Treatment of cervical cancer cells with bortezomib elevated the level of p53 but not hDlg, hScribble or hMAGI. Immunohistochemical analysis revealed elevated HDAC1/HDAC2 expression in cervical dysplasia and cervical carcinoma versus normal cervical epithelium. The combination of bortezomib and HDAC inhibitor trichostatin A or vorinostat shows synergistic killing of HPV-positive, but not HPV-negative, cervical cancer cell lines. Similarly, treatment of HeLa xenografts with the combination of bortezomib and trichostatin A retarded tumor growth significantly more effectively than either agent alone.

CONCLUSIONS

A combination of proteasome and HDAC inhibitors, including bortezomib and vorinostat, respectively, warrants exploration for the treatment of cervical cancer.

Administration of HPV DNA vaccine via electroporation elicits the strongest CD8+ T cell immune responses compared to intramuscular injection and intradermal gene gun delivery

DNA vaccines are an attractive approach to eliciting antigen-specific immunity. Intracellular targeting of tumor antigens through its linkage to immunostimulatory molecules such as calreticulin (CRT) can improve antigen processing and presentation through the MHC class I pathway and increase cytotoxic CD8+ T cell production. However, even with these enhancements, the efficacy of such immunotherapeutic strategies is dependent on the identification of an effective route and method of DNA administration. Electroporation and gene gun-mediated particle delivery are leading methods of DNA vaccine delivery that can generate protective and therapeutic levels of immune responses in experimental models. In this study, we perform a head-to-head comparison of three methods of vaccination--conventional intramuscular injection, electroporation-mediated intramuscular delivery, and epidermal gene gun-mediated particle delivery--in the ability to generate antigen-specific cytotoxic CD8+ T cell responses as well as anti-tumor immune responses against an HPV-16 E7 expressing tumor cell line using the pNGVL4a-CRT/E7(detox) DNA vaccine. Vaccination via electroporation generated the highest number of E7-specific cytotoxic CD8+ T cells, which correlated to improved outcomes in the treatment of growing tumors. In addition, we demonstrate that electroporation results in significantly higher levels of circulating protein compared to gene gun or intramuscular vaccination, which likely enhances calreticulin's role as a local tumor anti-angiogenesis agent. We conclude that electroporation is a promising method for delivery of HPV DNA vaccines and should be considered for DNA vaccine delivery in human clinical trials.

A phase I trial of a human papillomavirus DNA vaccine for HPV16+ cervical intraepithelial neoplasia 2/3

PURPOSE

To evaluate the safety and immunogenicity of a therapeutic human papillomavirus (HPV)16 DNA vaccine administered to women with HPV16+cervical intraepithelial neoplasia (CIN)2/3.

EXPERIMENTAL DESIGN

This phase I trial incorporated the standard '3+3'' dose-escalation design with an additional 6 patients allocated to the maximally tolerated dose. Healthy adult women with colposcopically directed, biopsy-proven HPV16+ CIN2/3 received 3 i.m. vaccinations (0.5, 1, or 3 mg) of a plasmid expressing a Sig-E7(detox)-heat shock protein 70 fusion protein on days 0, 28, and 56, and underwent standard therapeutic resection of the cervical squamocolumnar junction at day 105 (week 15). The safety and immunogenicity of the vaccine and histologic outcome based on resection at week 15 were assessed.

RESULTS

Fifteen patients were evaluable (3 each at 0.5 and 1mg, 9 at 3 mg). The vaccine was well tolerated: most adverse events were mild, transient injection-site discomfort; no dose-limiting toxicities were observed. Although HPVE7-specific T-cell responses to E7 detected by enzyme-linked immunospot assays (IFN-gamma) were of low frequency and magnitude, detectable increases in response subsequent to vaccination were identified in subjects in the second and third cohorts. Complete histologic regression occurred in 3 of 9 (33%; 7-70% confidence interval) individuals in the highest-dose cohort. Although the difference is not significant, it is slightly higher than would be expected in an unvaccinated cohort (25%).

CONCLUSIONS

This HPV16 DNA vaccine was safe and well tolerated. Whereas it seems possible to elicit HPV-specific T-cell responses in patients with established dysplastic lesions, other factors are likely to play a role in lesion regression.

A phase I trial of a human papillomavirus DNA vaccine for HPV16+ cervical intraepithelial neoplasia 2/3

PURPOSE

To evaluate the safety and immunogenicity of a therapeutic human papillomavirus (HPV)16 DNA vaccine administered to women with HPV16+cervical intraepithelial neoplasia (CIN)2/3.

EXPERIMENTAL DESIGN

This phase I trial incorporated the standard '3+3'' dose-escalation design with an additional 6 patients allocated to the maximally tolerated dose. Healthy adult women with colposcopically directed, biopsy-proven HPV16+ CIN2/3 received 3 i.m. vaccinations (0.5, 1, or 3 mg) of a plasmid expressing a Sig-E7(detox)-heat shock protein 70 fusion protein on days 0, 28, and 56, and underwent standard therapeutic resection of the cervical squamocolumnar junction at day 105 (week 15). The safety and immunogenicity of the vaccine and histologic outcome based on resection at week 15 were assessed.

RESULTS

Fifteen patients were evaluable (3 each at 0.5 and 1mg, 9 at 3 mg). The vaccine was well tolerated: most adverse events were mild, transient injection-site discomfort; no dose-limiting toxicities were observed. Although HPVE7-specific T-cell responses to E7 detected by enzyme-linked immunospot assays (IFN-gamma) were of low frequency and magnitude, detectable increases in response subsequent to vaccination were identified in subjects in the second and third cohorts. Complete histologic regression occurred in 3 of 9 (33%; 7-70% confidence interval) individuals in the highest-dose cohort. Although the difference is not significant, it is slightly higher than would be expected in an unvaccinated cohort (25%).

CONCLUSIONS

This HPV16 DNA vaccine was safe and well tolerated. Whereas it seems possible to elicit HPV-specific T-cell responses in patients with established dysplastic lesions, other factors are likely to play a role in lesion regression.

Vaccination with HPV16 L2E6E7 fusion protein in GPI-0100 adjuvant elicits protective humoral and cell-mediated immunity

A vaccine comprising human papillomavirus type 16 (HPV16) L2, E6 and E7 in a single tandem fusion protein (termed TA-CIN) has the potential advantages of both broad cross-protection against HPV transmission through induction of L2 antibodies able to cross neutralize different HPV types and of therapy by stimulating T cell responses targeting HPV16 early proteins. However, patients vaccinated with TA-CIN alone develop weak HPV neutralizing antibody and E6/E7-specific T cell responses. Here we test TA-CIN formulated along with the adjuvant GPI-0100, a semi-synthetic quillaja saponin analog that was developed to promote both humoral and cellular immune responses. Subcutaneous administration to mice of TA-CIN (20 microg) with 50microg GPI-0100, three times at biweekly intervals, elicited high titer HPV16 neutralizing serum antibody, robust neutralizing titers for other HPV16-related types, including HPV31 and HPV58, and neutralized to a lesser extent other genital mucosatropic papillomaviruses like HPV18, HPV45, HPV6 and HPV11. Notably, vaccination with TA-CIN in GPI-0100 protected mice from cutaneous HPV16 challenge as effectively as HPV16 L1 VLP without adjuvant. Formulation of TA-CIN with GPI-0100 enhanced the production of E7-specific, interferon gamma producing CD8(+) T cell precursors by 20-fold. Vaccination with TA-CIN in GPI-0100 also completely prevented tumor growth after challenge with 5x10(4) HPV16-transformed TC-1 tumor cells, whereas vaccination with TA-CIN alone delayed tumor growth. Furthermore, three monthly vaccinations with 125 microg of TA-CIN and 1000 microg GPI-0100 were well tolerated by pigtail macaques and induced both HPV16 E6/E7-specific T cell responses and serum antibodies that neutralized all HPV types tested.

RNA interference-mediated in vivo silencing of fas ligand as a strategy for the enhancement of DNA vaccine potency

Intradermal administration of DNA vaccines encoding luciferase represents a convenient method to assess gene expression in vivo. Gene silencing by intradermal gene gun administration of DNA encoding short hairpin RNA (shRNA) may represent an effective technique for the specific knockdown of gene expression in vivo. In the current study, we characterized luciferase gene expression over time in vivo by noninvasive bioluminescence imaging. Furthermore, we characterized in vivo luciferase gene silencing with DNA encoding shRNA targeting luciferase. We also characterized human papillomavirus type 16 (HPV-16) E7-specific CD8(+) T cell immune responses in mice immunized with E7 DNA and DNA encoding shRNA targeting Fas ligand (FasL), a key proapoptotic signaling protein. Our results indicated that coadministration of DNA encoding shRNA targeting luciferase significantly reduced luciferase expression in mice intradermally administered luciferase DNA. Furthermore, we observed that mice vaccinated with E7-expressing DNA coadministered with DNA encoding shRNA targeting FasL generated significantly enhanced E7-specific CD8(+) cytotoxic T cell responses as well as potent therapeutic antitumor effects against E7-expressing tumors. Thus, intradermal administration of DNA encoding shRNA represents a plausible approach to silence genes in vivo and a potentially useful tool to enhance DNA vaccine potency.