Inovio Biomedical announces additional immunogenicity data from therapeutic cervical cancer vaccine trial

Feb 8 2010

Inovio Biomedical Corporation (NYSE Amex: INO), a leader in DNA vaccine design, development and delivery, announced today additional 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. Similar to previously reported data from the initial lowest dose cohort of this phase I trial, the vaccine was found to be generally safe and well tolerated. While previously reported data showed significant cellular and humoral immune responses, data from this second, intermediate dose group highlighted a significantly increased and dose-related immune response specific to the antigens targeted by the vaccine.

“We are extremely pleased with the safety and tolerability profile of VGX-3100. Furthermore, analyses of the vaccinated subjects from the first two cohorts indicate that this vaccine is highly immunogenic, generating antigen-specific T-cell and antibody responses that are amongst the highest reported from any previous human studies of DNA vaccines”

“We are extremely pleased with the safety and tolerability profile of VGX-3100. Furthermore, analyses of the vaccinated subjects from the first two cohorts indicate that this vaccine is highly immunogenic, generating antigen-specific T-cell and antibody responses that are amongst the highest reported from any previous human studies of DNA vaccines,” stated Dr. J. Joseph Kim, President and CEO.

“While recent HPV preventive vaccines have been successful in protecting against infections that may lead to cervical cancer, Inovio’s therapeutic vaccine targets the millions of women already infected with HPV and is intended to treat pre-cancerous cells and cervical cancer caused by this virus. Current vaccines do not serve this group of women,” Dr. Kim added.

This dose escalation study was designed to test the safety and immunogenicity of VGX-3100 in women with a previous history of cervical intraepithelial neoplasia (CIN) 2/3, a precursor lesion prior to the development of cancer. The trial is enrolling patients in three cohorts of six subjects each with DNA vaccine doses at 0.6 mg (0.3 mg each of two DNA plasmids), 2.0 mg, and 6.0 mg. The immunization regimen consists of each subject receiving the respective dose at day 0, month 1 and month 3. The vaccine is delivered using Inovio’s proprietary CELLECTRA® intramuscular electroporation delivery device.

All six patients in the second, intermediate dose cohort have been enrolled; samples from the first four patients have been evaluated for immune responses. As with the first cohort, the vaccination procedures were well-tolerated by the subjects in the second cohort. In general, reported adverse events and injection site reactions were mild to moderate and required no treatment.

The preliminary immunological analysis of blood samples collected before and after vaccination indicated the induction of antigen-specific immune responses against the target proteins produced by the vaccine. Antigen-specific cytotoxic T-lymphocyte (CTL) responses were observed against all four antigens (E6 and E7 proteins for HPV types 16 and 18). In this cohort, 2 of 4 vaccinated subjects (50%) developed significant CTL responses, with average responses of 532 SFU per million cells after three immunizations. This was a 71% increase in CTL responses compared to the lowest dose cohort, which also yielded 50% responders (3 out of 6) and average CTL responses of 311 SFU per million cells. Generation of tumor-specific T cell responses is believed to be an important characteristic of a cancer therapeutic vaccine.

Inovio also tested the samples for antibody responses against the target antigens and observed strong antibody responses in 4 of 4 subjects (100%). Antibodies were generated against all four antigens, as tested by the enzyme-linked immunosorbent assay (ELISA). The current results were an improvement over the results from the first cohort, in which 5 of 6 vaccinated subjects (83%) developed strong antibody responses. The level of antibody responses in the current cohort was 5 - 10 fold higher than that observed in the lowest-dose cohort. The average antibody titer to both HPV E7 proteins in the current cohort was greater than 1:50,000.

Specific antibody responses to tumor antigens can function as an important surrogate potency marker for determining the immunogenicity of a vaccine, i.e. the ability of a vaccine to induce an immune response. Furthermore, Inovio believes these results underscore the potential usefulness of its DNA vaccine platform against infectious disease targets, where generation of antibodies has been shown to be protective.

Inovio expects full enrollment of all three cohorts in the first half of 2010 and complete immunogenicity and safety data to be reported in Q4 2010.