Immunization with a poly (lactide co-glycolide) encapsulated plasmid DNA expressing antigenic regions of HPV 16 and 18 results in an increase in the precursor frequency of T cells that respond to epitopes from HPV 16, 18, 6 and 11.

A phase II trial was conducted in subjects with human papillomavirus (HPV) associated high-grade cervical dysplasia testing the safety and efficacy of a microparticle encapsulated pDNA vaccine. Amolimogene expresses T cell epitopes from E6 and E7 proteins of HPV types 16 and 18. An analysis was performed on a subset of HLA-A2+ subjects to test whether CD8+ T cells specific to HPV 16, 18, 6 and 11 were increased in response to amolimogene immunization. Of the 21 subjects receiving amolimogene, 11 had elevated CD8+ T cell responses to HPV 16 and/or 18 peptides and seven of these also had increases to corresponding HPV 6 and/or 11 peptides. In addition, T cells primed and expanded in vitro with an HPV 18 peptide demonstrated cross-reactivity to the corresponding HPV 11 peptide. These data demonstrate that treatment with amolimogene elicits T cell responses to HPV 16, 18, 6 and 11.

In vivo electroporation enhances the potency of poly-lactide co-glycolide (PLG) plasmid DNA immunization.

Immunization with plasmid DNA that has been encapsulated in poly lactide-co-glycolide (PLG) microparticles targets the plasmid DNA to antigen presenting cells and elicits immune responses to the encoded antigen(s). Application of a series of electrical pulses (EPT) immediately following unformulated DNA injection enhances expression of the encoded antigen and increases immune responses. The combination of using EPT before or after PLG-encapsulated plasmid DNA immunization was tested to determine if enhanced immune responses would be generated. The results show that the combination lead to both enhanced expression of antigen and more robust T cell responses, even if EPT was applied prior to immunization. The data also demonstrate that recruitment of phagocytes to the injection site was markedly enhanced by EPT, and this resulted in an increase of the antigen expression levels in these cells. Co-administration of microparticles and EPT also effected localized necrosis of muscle fibers, caused persistent Th-1-modulated cytokine production, and lead to the release of two endogenous adjuvants, uric acid and HMGB1. In all, we describe that increased immunogenicity observed with the combination of PLG-encapsulated plasmid DNA microparticle with EPT was caused by an increase in the recruitment of antigen presenting cells which mediated a more robust T cell response than observed with immunization alone.

Consecutive low doses of cyclophosphamide preferentially target Tregs and potentiate T cell responses induced by DNA PLG microparticle immunization.

Cyclophosphamide in combination with immunotherapeutic approaches preferentially impinges on T(reg) activity and allows for robust generation of T cell effectors. Reduced dosages of cyclophosphamide are necessary to restrict its cytotoxic effects to the negative regulatory cell populations while sparing effector lymphocytes. We investigated cyclophosphamide dosing in combination with ZYC300, a PLG-encapsulated plasmid DNA vaccine which encodes the cytochrome P450 family member, CYP1B1, a known human tumor-associated antigen. In mice, three consecutive, low doses of cyclophosphamide comprised a superior regimen in enhancing the magnitude, diversity of epitopes, and avidity to individual epitopes of specific T cell responses when compared to regimens that used either a single low or a single high dose. Consecutive low doses of cyclophosphamide predominantly targeted T(regs) while sparing overall T lymphocyte counts. Thus, we report the synergistic activity of pharmacologic T(reg) depletion with cyclophosphamide on quantitatively and qualitatively increasing T cell responses to a known human tumor-associated antigen.

Repeated immunization with plasmid DNA formulated in poly(lactide-co-glycolide) microparticles is well tolerated and stimulates durable T cell responses to the tumor-associated antigen cytochrome P450 1B1.

Injection of microparticle-encapsulated DNA elicits immune responses to plasmid-encoded antigens in mice and humans. Cytochrome P450 CYP1B1 (CYP1B1) is a member of the CYP1 P450 enzyme family that is overexpressed in a variety of solid tumors. The work described herein was performed to study the kinetics of stimulating T cell responsiveness with an encapsulated DNA encoding CYP1B1 and provides support for the clinical development of this formulation. Immunization of HLA-A2/Kb transgenic mice with human CYP1B1 encoding plasmid DNA formulated in poly(lactide-co-glycolide) (PLG) microparticles elicits CD8+ T cells that respond to human CYP1B1-positive target cells. The duration of the immune response, the effect on the immune response of multiple injections, and the safety of repeated injections were studied. These results show that the PLG-encapsulated DNA therapeutic elicits durable immune responses to CYP1B1, the responses are dependent on repeat immunization, and that the formulation is well tolerated.

ZYC101a for treatment of high-grade cervical intraepithelial neoplasia: a randomized controlled trial.

OBJECTIVE: The objective of this study was to assess the safety and efficacy of a novel therapeutic, ZYC101a, for the treatment of women with histologically confirmed cervical intraepithelial neoplasia (CIN) 2/3. ZYC101a contains plasmid-DNA-encoding fragments derived from the E6 and E7 proteins of human papillomavirus (HPV) 16 and 18, and is formulated within small biodegradable microparticles. METHODS: A multicenter, double-blind, randomized, placebo-controlled trial was conducted in a group of women with biopsy-confirmed CIN 2/3. Subjects were randomized to 3 intramuscular doses of either placebo or ZYC101a (100 or 200 microg). Six months after the first injection, subjects underwent cervical conization. The primary endpoint for this study was histologically confirmed resolution of CIN 2/3. A total of 161 subjects were randomized, dosed, and evaluated for safety. After central pathology review, 127 subjects were evaluable for efficacy. RESULTS: The most common adverse events were related to the injection site, were mild to moderate, and did not worsen at later treatments. The proportion of subjects who resolved was higher in the ZYC101a groups compared to placebo (43% versus 27%), but the difference was not statistically significant (P =.12). In a prospectively defined population of women younger than 25 years (n = 43), resolution was significantly higher in the combined ZYC101a groups compared to placebo (70% versus 23%; P =.007). ZYC101a activity was not restricted to HPV-16-or HPV-18-positive lesions. CONCLUSIONS: ZYC101a was shown to be well tolerated in all patients and to promote the resolution of CIN 2/3 in women younger than 25 years. LEVEL OF EVIDENCE: I

Formulations containing poly(lactide-co-glycolide) and plasmid DNA expression vectors.

DNA expression vectors have the potential to be useful therapeutics for a wide variety of applications. However, development has been hindered by the lack of systems that provide protection from nuclease-based attack, enable cell or tissue localisation, promote adequate gene expression or provide for controlled release. At least one synthetic polymer, poly(lactide-co-glycolide) (PLG), may provide benefit in this regard. This polymer has a history of safe use in humans, has been demonstrated effective as a delivery system, its use is not hindered by composition patents, and Good Manufacturing Practices grade material is readily available from commercial sources. Safety and applicability to clinical medicine have been proven by use of the polymer as a microparticle delivery vehicle for peptides (luteinizing hormone releasing hormone agonist peptides; Lupron Depot [TAP Pharmaceuticals]; Zoladex [AstraZeneca]) and proteins (human growth hormone recombinant protein, Nutropin Depot [Genentech]). This report focuses on the expanding field of PLG-based DNA delivery and provides a review on research and clinical experience with PLG-plasmid formulations.

Gene delivery with in-situ crosslinking polymer networks generates long-term systemic protein expression.

Two polyethylene oxide-based delivery systems comprised of reacting PEG polymers were designed for the delivery of DNA expression vectors. The polymers are formulated with the DNA and injected into the muscle, wherein a crosslinked matrix forms in-situ. The matrix resembles a viscous solution (formulation A) or a gel (formulation B). The reacting PEG polymers do not interact with, but entrap the DNA. The formation of the matrix does not affect the supercoiling of the incorporated DNA. The polymers are biocompatible and biodegradable due to the presence of hydrolytically labile bonds in one of the components. Measurement of degradation in vivo suggests that a significant amount of the polymer disappears from the injected muscle by 28 days post injection. Administration to mice of SEAP plasmid DNA formulated with the PEG polymers results in SEAP expression. Expression levels are similar to those of unformulated DNA, but the duration of gene expression is significantly longer in immunocompetent animals receiving the formulated DNA. Significantly lower anti-SEAP IgG titers are elicited by network-formulated DNA relative to unformulated DNA, even though expression levels are comparable. The data suggests that the matrix extends duration of expression by reducing the anti-SEAP immune response so that these delivery systems may be useful for prolonged gene expression following a single intramuscular injection.

Immunotherapy of human cervical high-grade cervical intraepithelial neoplasia with microparticle-delivered human papillomavirus 16 E7 plasmid DNA.

OBJECTIVE: The purpose of this study was to evaluate the safety of the administration of a bacterial expression plasmid encoding a 13 amino acid sequence that is highly homologous with human papillomavirus E7 within poly (lactide-co-glycolide) microparticles (ZYC101) in women with HLA A2+ antigen and persistent cervical intraepithelial neoplasia grade 2/3 and human papillomavirus 16. STUDY DESIGN: Fifteen women entered an institutional review board-approved dose-escalating phase I study with the use of three levels of blood monitoring and urine studies, Papanicolaou tests, and colposcopy. Escalation required no serious adverse events. Immunologic responses were evaluated in peripheral blood with the use of human papillomavirus peptide-stimulated interferon gamma enzyme-linked immunosorbent assay for T-cell reactivity. In cervical secretions, immunoglobulin A anti-human papillomavirus 16 E2 concentrations were measured. Three doses every 3 weeks were followed 4 weeks later by surgical excision. RESULTS: No serious adverse events occurred. Five women had complete histologic responses; 11 women had human papillomavirus-specific T-cell responses. Four of five complete histologic responses developed immunoglobulin A anti-E2-specific antibody. CONCLUSION: ZYC101 warrants further investigation because of a 33% complete histologic responses, a 73% immunologic response, and no serious adverse events.

Encapsulated plasmid DNA treatment for human papillomavirus 16-associated anal dysplasia: a Phase I study of ZYC101.

High-grade dysplasia induced by high-risk types of human papillomavirus (HPV) precedes invasive cancer in anal squamous epithelium just as it does in the cervix. A therapeutic HPV vaccine strategy as a potential treatment for anal dysplasia was tested in a standard Phase I dose escalation trial. The primary objective was to evaluate the safety of the agent; additional study aims were to evaluate the histological response, immune response, and effect on anal HPV-16 infection. Each subject was treated with four i.m. injections of 50-400 microg of ZYC101 at 3-week intervals. ZYC101 is composed of plasmid DNA encapsulated in biodegradable polymer microparticles. The plasmid DNA encodes for multiple HLA-A2-restricted epitopes derived from the HPV-16 E7 protein, one of two HPV oncoproteins consistently expressed in neoplastic cells. Fifty-six potential anal dysplasia subjects were screened to identify 12 eligible subjects with HPV-16 anal infection and a HLA-A2 haplotype. The investigational agent was well tolerated in all subjects at all dose levels tested. Three subjects experienced partial histological responses, including one of three subjects receiving the 200-microg dose and two subjects at the 400-microg dose level. Using a direct Elispot, 10 of 12 subjects demonstrated increased immune response to the peptide epitopes encoded within ZYC101; each continued to show elevated immune responses 6 months after the initiation of therapy. These results support the continued investigation of a therapeutic vaccination strategy for anal dysplasia.

Inhibition of NF-kappaB activity by plasmid expressed alphaMSH peptide.

Alpha-Melanocyte Stimulating Hormone (alphaMSH) is a neuroimmunomodulatory peptide with remarkable anti-inflammatory properties. Daily or twice daily administration of the peptide reduces the symptoms of several inflammatory animal disease models and the peptide has demonstrated safety in human trials. Unfortunately, the pharmacokinetics of peptide delivery are not favorable from the pharmaceutical perspective. For this reason, plasmid-based vectors were created that constitutively express the immunomodulatory peptide. The fusion constructs encode the 13 amino acids of alphaMSH in frame with the first domain of serum albumin, separated by a linker and furin cleavage sites. The fusion proteins were expressed and processed in human fetal kidney (293) cells. Supernatant from B16/F10 cells transfected with the constructs stimulated secretion of melanin from melanocytes. Furthermore, transfected cytoskeletal muscle (Sol8) cells secreted bioactive alphaMSH that reduced NF-kappaB-mediated transcriptional activation of a luciferase reporter gene. The activity of these vectors provides tools and the impetus for testing the constructs in several animal models of chronic inflammation.

Clinical trials in cervical intraepithelial neoplasia: balancing the need for efficacy data with patient safety.

OBJECTIVE.: Trial designs for novel nonsurgical, nonablative therapies for cervical intraepithelial neoplasia grades 2 and 3 (CIN 2,3) must ensure patient safety while providing sufficient time to show clinical effects. We propose an observation period based on literature and current practice. MATERIALS AND METHODS.: We reviewed 3 types of literature regarding observation of untreated CIN 2,3: 1) the management of CIN in pregnancy, perhaps the best existing model of observation; 2) the natural history of untreated CIN 2,3; and 3) the optimal means of protecting patient safety during longer-term follow-up of untreated CIN 2,3 lesions. RESULTS.: Data from both the pregnant and nonpregnant patient populations indicate that delaying treatment of CIN for periods of several weeks to several months is rarely associated with clinically significant disease progression. Screening and follow-up criteria that promote patient safety have been suggested and seem adaptable to clinical trials. CONCLUSIONS.: Careful screening and follow-up of patients with CIN 2,3 allows an observation period of at least 6 months after nonsurgical, nonablative therapy in clinical trials.