Inovio Pharmaceuticals, Inc., a leader in the development of therapeutic and preventive vaccines against cancers and infectious diseases, announced that early data from a phase I study assessing its PENNVAX-G global HIV vaccine plus a virus vector vaccine, Modified Vaccinia Ankara-Chiang Mai Double Recombinant (MVA-CMDR), as a unique prime-boost preventive HIV vaccination strategy has demonstrated strong immune responses and safety. These results were presented at the AIDS Vaccine Conference in Bangkok, Thailand. This interim data was from the first cohort of 11 healthy subjects enrolled in the US as part of the first phase of the study to assess safety of the prime-boost combination vaccine. Enrollment will now continue in three sites in Africa in the next phase of the study.

The National Institute of Allergy and Infectious Diseases (NIAID), part of the US National Institutes of Health (NIH), is sponsoring this randomized, open label trial phase I study, called RV262, which will enroll 92 total participants and is designed to assess safety and immune responses. The study is being conducted by the US Military HIV Research Programme (MHRP) through its clinical research network in the US and Africa. This clinical trial was designed to test safety and immunogenicity of a unique heterologous DNA/recombinant poxvirus prime-boost preventive HIV immunization strategy aimed at global coverage. Together the vaccines are designed to deliver a diverse mixture of antigens for HIV-1 subtypes A, B, C, D and E.

Volunteers were given a priming immunization with Inovio's PENNVAX-G synthetic consensus immunogen at months 0 and 1, followed by boosting with MVA-CMDR at months 3 and 6. Immunomonitoring was performed at pre-immunization and at two weeks post-DNA and MVA immunizations, respectively.

Early analysis of this initial data revealed a strong cell-mediated immune response, with CD4+ and CD8+ T cells specific for both the gag and env antigens encoded by the prime and boost agents. Significantly, anti-env CD4+ T-cell immune responses were noted in 100% (11 of 11) of evaluated subjects and CD8+ T-cell responses were noted in 45% (5 of 11) of evaluated subjects after the first MVA boost following the two DNA vaccinations. The env specific CD4+ and CD8+ T-cell response rates were noted to be 73% (8 of 11) and 45% (5 of 11) respectively after the second MVA boost.

Dr J Joseph Kim, Inovio's president and CEO, said: “We are pleased to see the response rate and magnitude of T-cell responses generated by the prime-boost vaccine combination. We believe that a 100% vaccine induced env-specific T-cell immune response result has not been achieved in previous HIV vaccine clinical trials. We look forward to completing and receiving the full data set from this study.”

PENNVAX-G is a SynCon multi-subtype optimized synthetic immunogen. Based on a consensus of env and gag antigens of HIV-1 global subtypes A, C, D, this synthetically created immunogen is intended to provide broad antibody and T-cell immune responses to target many divergent strains of this challenging disease. Inovio's electroporation systems have been shown to increase immune responses to a DNA-based immunogen by a 100 times or more and have been shown to be safe and well-tolerated in multiple human studies. Inovio's SynCon immunogens against cervical dysplasias and cancer as well as HIV Clade B (both delivered using the CELLECTRA electroporation device), have previously achieved best-in-class T-cell immune responses, which are thought to be important in controlling HIV infection and transmission.

The US Military HIV Research Programme (MHRP)—centered at Walter Reed Army Institute of Research (WRAIR) and part of the US Medical Research and Materiel Command—conducts research to develop an effective HIV vaccine and integrates prevention, treatment, diagnosis and monitoring as part of an international effort to protect troops and reduce the risk of HIV infection worldwide. MHRP has developed five state-of-the-art international research sites in the US, Africa and Asia. The programme collaborates on HIV prevention care and treatment services, funded by the President's Emergency Plan for AIDS Relief (PEPFAR), with African militaries and in the communities where it conducts research.

In 2009, MHRP announced results of an Army-sponsored clinical trial in Thailand that demonstrated for the first time a modest ability to protect against HIV infection, reducing the number of infections by 31.2 percent. MHRP researchers are now working with scientists around the world, with the support of NIAID, to dissect the trial results to inform basic research and design future clinical trials to translate this scientific milestone into a deployable vaccine.