Inovio HIV vaccine elicits nearly 100% immune response rates in a clinical study

Amongst highest levels of immune responses ever demonstrated in an HIV vaccine human study.

Inovio Pharmaceuticals' HIV vaccine, Pennvax-GP, produced some of the highest overall levels of immune response rates (cellular and humoral) ever demonstrated in a human study by an HIV vaccine. The vaccine candidate, Pennvax-GP, consists of a combination of four HIV antigens designed to cover multiple global HIV strains and generate both an antibody (humoral) immune response as well as a T cell (cellular) immune response to both potentially prevent and treat HIV.

These preliminary results are from a study supported by the HIV Vaccine Trials Network (HVTN) and the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH) in collaboration with Inovio. The study evaluated a four-dose regimen of Pennvax-GP DNA vaccine administered by intradermal (ID) or intramuscular (IM) administration in combination with a DNA encoded immune activator, IL-12 (INO-9012). Overall, 71 of 76 (93%) evaluable vaccinated participants showed a CD4+ or CD8+ cellular immune response to at least one of the vaccine antigens (env A, env C, gag, or pol). Similarly, 62 of 66 (94%) evaluated participants demonstrated an env specific antibody response. None of the placebo recipients (0 of 9; 0%) demonstrated either a cellular or an antibody response in the study. Notably, among the participants receiving Pennvax-GP vaccine and IL-12 with ID immunization, 27 of 28 (96%) participants demonstrated a cellular response and 27 of 28 (96%) demonstrated an HIV env specific antibody response.

Among the evaluated participants receiving Pennvax-GP and IL-12 via IM vaccination, 27 of 27 (100%) demonstrated a cellular response and 19 of 21 (90%) demonstrated an env specific antibody response. Similar immune responses and response rates were achieved via both ID and IM administration of the vaccine although participants vaccinated via ID vaccine administration received 1/5th the dose of vaccine compared with those vaccinated via IM administration.

This breakthrough data was presented at a plenary session at the 2017 HVTN Spring Full Group Meeting on 23 May in Washington, DC by the Protocol Co-Chair of the HVTN 098 study, Dr Stephen De Rosa, Research Associate Professor, Laboratory Medicine at the University of Washington and Fred Hutchinson Cancer Research Center. The HVTN 098 trial was the first clinical study of Pennvax-GP. The randomized, placebo-controlled multi-center study enrolled 94 subjects (85 vaccine and 9 placebo) to characterize and optimize Pennvax-GP immunization regimens delivered through vaccinations using either IM or ID delivery.

Dr De Rosa, said: "The preliminary results of HVTN 098 are remarkable for a number of reasons. In HVTN 098, nearly all individuals vaccinated with the regimens including IL-12 had detectable CD4 responses and over half had CD8 T cell responses. Similarly, the antibody response rate was 100% or close to 100% for several of the env antigens tested in the assay. Thus, these high response rates are exceptional. Further studies will be needed to determine if this vaccine candidate can safely and effectively prevent HIV infection."

Dr J. Joseph Kim, Inovio’s President & CEO, said, "These results are among the highest ever responses we’ve seen with an HIV vaccine, and they are remarkably consistent with our recent data reported from our Ebola, Zika and MERS clinical trials in terms of demonstrating nearly 100% vaccine response rates with very favorable safety profile. Furthermore, our newer and more tolerable IDl vaccine delivery device showed that we can elicit very high immune responses at a much lower dose. We look forward to advancing Pennvax-GP into later-stage clinical development with our partners and collaborators."