Inovio Pharmaceuticals, Inc. a leader in the development of therapeutic and preventive vaccines against cancers and infectious diseases, announced that novel data from a preclinical study of its SynCon DNA vaccine against HIV were published in two separate scientific journals. In vaccinated animals, the studies demonstrated Inovio's HIV vaccine's ability to harness the power of the immune system, generating unique immune system responses, significant antigen-specific T-cell responses, and protection from the virus.

The results were published in two peer-reviewed journals in papers co-authored by researchers from Inovio and its academic collaborators: Vaccine published a paper entitled “Immunogenicity of a novel engineered HIV-1 clade C synthetic consensus-based envelope DNA vaccine”; PLoS One published the paper “Long-term programming of antigen-specific immunity from gene expression signatures in the PBMC of rhesus macaques immunized with an SIV DNA vaccine.”

In the first study, the investigators generated a synthetic, optimized DNA vaccine encoding for a novel HIV envelope clade C protein utilizing Inovio's SynCon vaccine design process. Further optimization processes were conducted including codon/RNA optimization, and addition of a Kozak sequence and IgE leader sequence to enhance the expression of the vaccine in humans. Developing a vaccine for clade C is considered to be a very high priority since this clade or sub-type of HIV virus is most prevalent in many parts of Africa, India, and China. When assessed in rigorous tests, this vaccine construct generated robust and high levels of T cell responses that were up to three times greater than T cell responses from other comparable DNA vaccine constructs targeting HIV envelope. Two phase I human studies will test the immunogenicity of this vaccine in human volunteers in the US and in Africa.

In the second study, the investigators assessed the protective effects of Inovio's Pennvax HIV DNA vaccines by examining an equivalent vaccine for the corresponding monkey virus, called SIV (Simian Immunodeficiency Virus). The vaccine was encoded for the three major proteins (e.g. gag, pol, and env antigens) encoded within the retroviral genome and was delivered using Inovio's proprietary electroporation (EP) technology. Researchers evaluated the treatment using a novel gene microarray analysis along with standard immunological and flow-based activation assays. They observed several gene sequences that were differentially regulated in vaccine-protected groups compared to non-vaccinated animals.

The novel microarray analysis used to test the vaccine effects of DNA vaccines demonstrated that Inovio's Pennvax vaccination led to the increased production of several gene sequences, including those involved in interferon signalling as well as those involved in immune cell trafficking and cell cycle progression. These results are relevant to humans because understanding these mechanisms could provide better insight into the ways immune responses could protect Pennvax-immunized individuals from infection and virus propagation and may aid in the further optimization of Inovio's HIV vaccine candidates currently in multiple phase I clinical studies.

Significantly, this study included a virus challenge in rhesus monkeys. Vaccinated animals were protected from a subsequent injection of the SIV (HIV-equivalent in non-human primates) virus (i.e. the vaccinated animals demonstrated strong control of viral replication and had significantly lower viral load) while also displaying significantly enhanced antigen-specific killer T cell responses, an outcome that Inovio has observed in multiple previous preclinical and clinical studies. By comparison, the non-vaccinated animals failed to control SIV virus infection. Generation of CD8+ killer T cells are considered instrumental in clearing cancerous or infected cells from the body and imperative to achieving sufficient potency of new vaccines against cancers and chronic infectious diseases such as HIV and hepatitis C.

Dr J Joseph Kim, Inovio's president and CEO, said: “This new preclinical data further validates the ability of Inovio's vaccines to induce powerful antigen-specific immune responses. In the past year, we have demonstrated best-in-class clinical immunogenicity data from our DNA vaccines for cervical cancer and HIV in phase I studies. Collectively, these clinical and preclinical studies further substantiate our product development efforts in these important disease areas.”

Late last year, Inovio announced interim immunogenicity and safety data in humans from its phase I clinical study of Pennvax-B, a DNA vaccine for the prevention of HIV clade B infection. Pennvax-B achieved high vaccine-induced response rates and strong magnitude of T cell immune responses in vaccinated subjects. Similar to reported results from a phase I clinical study of Inovio's therapeutic DNA vaccine for cervical cancer, the response rates and magnitude of responses achieved in this study were significantly higher than those seen previously from other DNA vaccine trials.

The complete immunogenicity data and end-of-study safety data from Pennvax-B study are expected in the third quarter of this year. In a separate study, Pennvax-B is also being tested as a therapeutic vaccine in HIV-positive volunteers, with immunogenicity and safety data expected in the fourth quarter of 2011.

Two phase I studies will test the optimized clade C DNA vaccine reported in the Vaccine paper. One study involves Inovio's global HIV DNA vaccine candidate, Pennvax-G (clades A, C, and D), which is currently being tested in a 92-patient global phase I clinical study in the US and Africa in a collaboration with the US Military HIV Vaccine Research Programme. Inovio plans to initiate another phase I study in mid-2012 with its Pennvax-GP vaccine (against HIV clades A and C; intradermal delivery), which is being developed using a multi-year $ 25-plus million NIAID development contract awarded to Inovio.

Inovio is developing a new generation of vaccines, called DNA vaccines, to treat and prevent cancers and infectious diseases.