Inovio Biomedical (Inovio) has reported interim safety and immunogenicity data from its therapeutic cervical cancer vaccine (VGX-3100) trial. VGX-3100 is a DNA vaccine targeting the E6 and E7 proteins of human papillomavirus (HPV) types 16 and 18 and is delivered via in vivo electroporation.
Reportedly, the vaccine was found to be generally safe and well tolerated, and achieved significant cellular and humoral immune responses at the lowest dose administered.
The phase I clinical trial was designed to test the safety and immunogenicity of VGX-3100 in women with a previous history of cervical intraepithelial neoplasia (CIN) 2/3.
The dose escalation study is enrolling patients in three cohorts of six subjects each with DNA vaccine doses at 0.6mg (0.3mg each of two DNA plasmids), 2.0mg, and 6.0mg. The immunisation regimen consists of each subject receiving three immunisations at the indicated dose.
The preliminary immunological analysis of blood samples collected before and after vaccine administration indicated the induction of vaccine-specific immune responses against the target antigens produced by the vaccine. Antigen-specific cytotoxic T-lymphocyte (CTL) responses were observed against all four antigens, i.e. E6 and E7 proteins for HPV types 16 and 18. The subjects were considered as responders if antigen-specific CTL responses greater than 50 spot forming units (SFU) per million white blood cells were observed.
The company said that 3 of 6 vaccinated subjects (50%) were deemed to be responders and yielded CTL responses ranging from 250 – 450 SFU per million cells after three immunisations. Inovio also tested the samples for antibody responses against the target antigens and observed strong antibody responses in 5 of 6 subjects (83%).
The VGX-3100 clinical trial is now enrolling the second cohort of patients. Inovio expects full enrollment of all three cohorts in the first half of 2010 and full analysis of immunogenicity and safety data by 3Q 2010.
Weiner, chairman of the scientific advisory board at Inovio, said: “We are pleased with the safety and tolerability profile of the VGX-3100 DNA vaccine delivered via in vivo electroporation. Significantly, although still preliminary, the immune analysis of the vaccinated subjects indicates that this vaccine is immunogenic and led to the induction of antigen-specific T-cell and antibody responses.
“We are excited by the demonstration in humans of a single, non-live vaccine inducing antibody and cellular immune responses from a single formulation. The induction of antigen-specific CTL responses, considered critical for cancer immunotherapy, has been difficult to achieve in vaccine trials.”