GMP Manufacturing and Initial Clinical Evaluation of a Tetravalent Live Attenuated Dengue Vaccine

Background: The mosquito-borne dengue virus (DENV) is a major international health concern. It is the top viral threat to the U.S. military and its third most significant infectious disease threat overall. The only prevention strategy is to avoid mosquito bites; there are no vaccines indicated for adults or specific therapies. This project is a critical step in the development of a tetravalent live attenuated vaccine to prevent dengue fever. Four DENV serotypes that can cause dengue fever. To safely and effectively prevent it, vaccines must target all four serotypes. We synthesized CodaVax-DENV™, a tetravalent live attenuated dengue vaccine, using Synthetic Attenuated Viral Engineering (SAVE) technology. SAVE uses genome "deoptimization" and de novo DNA synthesis to generate attenuated viruses with hundreds of silent synonymous mutations. SAVE viruses have amino acid sequences identical to those of the corresponding wildtype (wt) viruses, but are translated more slowly. The CodaVax-DENV component viruses representing each of the four serotypes are identical to currently circulating wt strains at the amino acid level. The tetravalent vaccine induces a balanced neutralizing antibody response in DENV susceptible animals, and a two-dose regimen ~30 days apart protects monkeys and mice and against wt DENV challenge. This dose regimen would make it practical for military use. In vitro and in vivo studies indicate further development of CodaVax-DENV is merited. All four viruses can be grown to production scale, and we are poised to manufacture enough finished drug product to complete Phase I clinical studies. Clinical studies coupled with process development planning for larger scale vaccine production are the next logical steps. Objectives/Hypotheses: Our objectives are to manufacture clinical grade (GMP) CodaVax-DENV tetravalent DENV vaccine, perform a first-in-human clinical trial to assess its safety and immunogenicity in adults, and prepare for scaled-up manufacturing of CodaVax-DENV. Primary Hypothesis: The safety and tolerability profile of CodaVax-DENV is sufficient to support further development of it as a prophylactic vaccine. Secondary Hypothesis: Inoculation with CodaVax-DENV will result in similar antibody response rates for all four serotypes, sufficient to support continued development as a balanced quadrivalent vaccine. Exploratory Hypotheses: CodaVax-DENV will result in other types of immune responses that provide a reasonable likelihood of improved safety and efficacy over vaccines that are currently FDA-licensed. CodaVax- DENV induced viremia is low and transient. Our ultimate goal is to develop a safe vaccine that can protect recipients against all four DENV serotypes and does not predispose them to enhanced disease, irrespective of preexisting serostatus. Specific Aims: Aim 1. Produce and release 1,000 vials of CodaVax-DENV drug product as a tetravalent LAV frozen formulation for injection. Aim 2. Conduct a first-in-human Phase I double-blind randomized placebo- controlled dose escalation trial to evaluate the safety and immunogenicity of three dose levels of CodaVax-DENV. Aim 3. Develop a large-scale manufacturing process plan for CodaVax-DENV. Study Design: GMP master virus banks will be generated for the CodaVax-DENV component viruses and the four GMP bulk virus strains will be manufactured. Viruses will be pooled during the fill process and >1,000 vials of CodaVax-DENV released. We will perform an evaluation and manufacturing process summary assessment. The data and insights gained will be used to create a process development plan for scaled-up manufacturing. To test CodaVax-DENV's safety and immunogenicity, a clinical trial will be conducted at the Naval Medical Research Center. About 48 healthy, flavivirus naïve 18-49-year-old military and civilian volunteers will be randomized 3:1 to two intramuscular doses of the vaccine or saline placebo in three dose-escalating cohorts. Adverse events, viremia, immunogenicity (levels of neutralizing antibodies), antibody balance, and cell-mediated immune responses will be monitored. Results will be analyzed to determine whether further development of the vaccine is warranted and for reporting to the FDA and ClinicalTrials.gov. Impact: Completion of the proposed production work will generate enough clinical-grade vaccine to complete first-in-human and dose-confirming clinical trials and leave us in position to scale up production for phase 2 trials. If the clinical trial meets safety and immunogenicity targets, vaccine development will continue. A safe effective vaccine is key to mitigating the risk of dengue disease and its complications, and would benefit the U.S. military, Veterans, and civilians. It could help prevent disease in 100 million individuals annually living in DENV endemic regions, which include parts of the U.S. Less