Clinical Development of a Cytomegalovirus DNA Vaccine: From Product Concept to Pivotal Phase 3 Trial.

2013 marks a milestone year for plasmid DNA vaccine development as a first-in-class cytomegalovirus (CMV) DNA vaccine enters pivotal phase 3 testing. This vaccine consists of two plasmids expressing CMV antigens glycoprotein B (gB) and phosphoprotein 65 (pp65) formulated with a CRL1005 poloxamer and benzalkonium chloride (BAK) delivery system designed to enhance plasmid expression. The vaccine's planned initial indication under investigation is for prevention of CMV reactivation in CMV-seropositive (CMV⁺) recipients of an allogeneic hematopoietic stem cell transplant (HCT).

Nonclinical biodistribution, integration, and toxicology evaluations of an H5N1 pandemic influenza plasmid DNA vaccine formulated with Vaxfectin®.

Vaxfectin(®) is a lipid-based adjuvant initially developed for use with plasmid DNA (pDNA) vaccines. Here we present detailed nonclinical assessments performed prior to Vaxfectin(®)'s first-in-man use, as an adjuvant in the H5N1 influenza vaccine VCL-IPT1. Following IM delivery to rabbits, VCL-IPT1 pDNA localized primarily to injection sites, where levels steadily declined over the 2 months examined.

Vaxfectin: a versatile adjuvant for plasmid DNA- and protein-based vaccines.

Importance Of The Field: Many vaccines require the use of an adjuvant to achieve immunity. So far, few adjuvants have advanced successfully through clinical trials to become part of licensed vaccines. Vaxfectin® (Vical, CA, USA) represents a next-generation adjuvant with promise as a platform technology, showing utility with both plasmid DNA (pDNA) and protein-based vaccines.

Phase 1 clinical trials of the safety and immunogenicity of adjuvanted plasmid DNA vaccines encoding influenza A virus H5 hemagglutinin.

Background: Development of vaccines against highly pathogenic avian influenza virus H5N1 subtypes posing a pandemic threat remains a priority. Limitations in manufacturing capacity and production time of conventional inactivated vaccines highlight the need for additional approaches.

Methods: We conducted two double-blind, placebo-controlled phase 1 studies involving a total of 103 healthy adults who received two intramuscular injections of Vaxfectin-adjuvanted plasmid DNA vaccine or placebo 21 days apart.

Vaxfectin, a cationic lipid-based adjuvant for protein-based influenza vaccines.

Mice were immunized either with unadjuvanted seasonal trivalent influenza vaccine (TIV) or TIV formulated with Vaxfectin, a cationic lipid-based adjuvant. Increasing doses of Vaxfectin resulted in increased hemagglutination-inhibition or anti-TIV ELISA antibody titers, with up to a 200-fold increase obtained with 900 microg of Vaxfectin. A >or=10-fold dose-sparing effect was demonstrated with Vaxfectin formulations.

Physical characterization and in vivo evaluation of poloxamer-based DNA vaccine formulations.

Background: Plasmid DNA (pDNA) vaccines have generated significant interest for the prevention or treatment of infectious diseases. Broader applications may benefit from the identification of safe and potent vaccine adjuvants. This report describes the development of a novel polymer-based formulation to enhance the immunogenicity of pDNA-based vaccines.

Novel microneutralization assay for HCMV using automated data collection and analysis.

In addition to being sensitive and specific, an assay for the assessment of neutralizing antibody activity from clinical trial samples must be amenable to automation for use in high-volume screening. To that effect, we developed a 96-well microplate assay for the measurement of HCMV-neutralizing activity in human sera using the HCMV-permissive human cell line HEL-299 and the laboratory strain of HCMV AD169. The degree to which neutralizing antibodies diminish HCMV infection of cells in the assay is determined by quantifying the nuclei of infected cells based on expression of the 72 kDa IE1 viral protein.

Nuclear gene delivery: the Trojan horse approach.

The nuclear envelope represents a formidable barrier to the transfer of plasmids to the cell nucleus, particularly in nondividing cells. The probability of intact plasmids arriving in the nucleus by a passive process is extremely low. There is substantial evidence in the literature that describes the transport of macromolecules, including plasmids, to the nucleus as a very inefficient process, and so far attempts to affect the active transport through the nuclear pores have achieved limited success.

Targeting malaria with polyamines.

During the asexual cycle of Plasmodium falciparum within the host erythrocyte, the parasite induces a stage-dependent elevation in the levels of polyamines by increased metabolism and uptake of extracellular pools. Polyamine amides of N-methylanthranilic acid have been synthesized which have embedded within them putrescine, spermidine, or spermine and from a charge perspective mimic natural polyamines. The interaction of these polyamine conjugates with human erythrocytes infected with malaria is described using fluorescent microscopy.

Development of anthrax DNA vaccines.

Over 120 years ago, Pasteur and Greenfield developed an in vitro procedure for producing a live-attenuated Bacillus anthracis bacterial culture capable of protecting livestock from anthrax disease. Since then, anthrax has become one of the best characterized bacterial pathogens with regard to mechanism of toxicity and vaccine development. Most developments have used live-attenuated strains, bacterial supernatants or protein subunit approaches.

A potential disruptive technology in vaccine development: gene-based vaccines and their application to infectious diseases.

Vaccine development requires an amalgamation of disparate disciplines and has unique economic and regulatory drivers. Non-viral gene-based delivery systems, such as formulated plasmid DNA, are new and potentially disruptive technologies capable of providing 'cheaper, simpler, and more convenient-to-use' vaccines. Typically and somewhat ironically, disruptive technologies have poorer product performance, at least in the near-term, compared with the existing conventional technologies.