Inovio Pharmaceuticals’ Pennvax-B vaccine has demonstrated positive T-cell immune responses in a Phase I clinical study in HIV-positive subjects.

Pennvax-B consists of SynCon immunogens targeting HIV gag, pol, and env proteins from HIV subtype B commonly found in North America and Europe.

The HIV-001 open label Phase I study enrolled 12 adult HIV-positive volunteers to evaluate safety and levels of immune responses generated by Pennvax-B vaccine delivered with its Cellectra electroporation device.

In the trial, 12 eligible subjects were given a four dose series (day 0, weeks 4, 8 and 16) of Pennvax-B containing 3mg of DNA/dose via intramuscular electroporation.

The study volunteers were required to be on a highly active antiretroviral therapy (HAART) regimen, have undetectable plasma viral load (<75 copies/mL), and have CD4 T lymphocyte counts above 400 cells/µL with nadirs over 200 cell/µL.

In 75% of subjects, Pennvax-B vaccine showed overall vaccine-specific T-cell responses against at least one of the three vaccine antigens (gag. pol, or env) following vaccination, and 50% of the subjects had strong vaccine induced antigen-specific responses above the pre-vaccination levels to at least two of the antigens.

Inovio president and CEO Joseph Kim said, "Coupled with positive data from two earlier trials, Inovio’s results demonstrate the potency of our synthetic vaccine technology platform and raises the potential for the development of therapeutic vaccines against HIV and other chronic infections.

"Together with our HIV prophylactic vaccine programs in collaboration with our partners at DAIDS and HVTN, this HIV therapy trial highlights our commitment to addressing one of the foremost global health issues of our time."

In a previous study (HVTN-080), three doses of the vaccine delivered together with an IL-12 cytokine plasmid via electroporation resulted in over 89% of the vaccinated subjects mounting an antigen-specific CD4+ or CD8+ T-cell response against at least one of the vaccine antigens.

The company intends to further study the effect of cytokines as well as the impact of therapeutic vaccination on HIV viral load in future clinical trials.