Inovio Biomedical Therapeutic Cervical Cancer Vaccine Demonstrates Safety And Immunogenicity In Clinical Trial

Main Category: Cervical Cancer / HPV Vaccine
Also Included In: Immune System / Vaccines;  Clinical Trials / Drug Trials
Article Date: 06 Oct 2009 - 3:00 PDT

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Inovio Biomedical Corporation (NYSE Amex: INO), a leader in DNA vaccine design, development and delivery, announced today 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. The vaccine was found to be generally safe and well tolerated, and achieved significant cellular and humoral immune responses at the lowest dose administered. Dr. David B. Weiner, Professor, University of Pennsylvania and Chairman of Inovio's Scientific Advisory Board, presented the data at the Vaccine 3rd Global Congress in Singapore in a presentation entitled, "Delivering on the Promise of DNA Vaccines for HIV and Cancer: From Bench to Clinical Data."

This 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, a precursor lesion prior to the development of cancer. This dose escalation study 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 three immunizations at the indicated dose. The vaccine is delivered using Inovio's proprietary CELLECTRA® intramuscular electroporation delivery device.

Inovio has completed immunizations of the lowest dose cohort. The interim safety analysis indicated that all six subjects tolerated the vaccine administration and electroporation procedure well over each of the three vaccinations. 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 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 (50 being a benchmark significantly beyond the normally existing background presence of CTL). By this measure, 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 immunizations. Inovio's scientists also tested the samples for antibody responses against the target antigens and observed strong antibody responses in 5 of 6 subjects (83%). Antibodies were generated to all three antigen components tested. Specific antibody responses to tumor antigens can function as an important surrogate potency marker for determining the immunogenicity of a vaccine.

Furthermore, Inovio believes they generally underscore the potential usefulness of the Inovio DNA vaccine platform in the vaccine arena.

Speaking at the Vaccine Congress, Dr. Weiner 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. It is impressive to get clear cellular immunity with this approach at such a low DNA vaccine dose."

Dr. J. Joseph Kim, Inovio's CEO, said, "Cervical cancer is the second leading cause of cancer-related deaths in women worldwide. While preventive vaccines have demonstrated efficacy in preventing HPV infection, they have shown no benefit in controlling cervical cancer in women already infected with HPV. A therapeutic vaccine capable of mobilizing the immune system to kill pre-cancerous and cancerous cervical cells would be a significant accomplishment and of great importance to the millions of individuals already infected with HPV. Inovio selected this important disease as its lead cancer target for its novel synthetic consensus SynCon™ DNA vaccines. We are excited by this preliminary data and the prospect of advancing a potential new cancer immunotherapy."

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.

About HPV, Cervical Cancer and Inovio's Therapeutic DNA Vaccine

Human papillomavirus (HPV) is the causative agent responsible for most cases of cervical cancer. Almost all HPV affecting the cervix is spread by sexual contact. There are over 100 distinct HPV types, but HPV types 16 and 18 are responsible for about 70% of cervical cancer incidences.

The world prevalence of HPV infection is estimated at 9 - 13% of the population. Globally, over 253,500 women die of cervical cancer each year, a majority of those deaths occurring in the developing world. The US Centers for Disease Control and Prevention estimated there would be 11,270 new cases of cervical cancer and 4,070 related deaths in the US in 2009 alone.

Preventive vaccines such as GARDASIL® and CERVARIX® have begun to play a role in limiting the contraction of HPV. However, the huge prevalence of patients already infected with HPV cannot be addressed by preventive vaccines - and there is no viable therapeutic vaccine or drug to fight HPV and cervical cancer.

Inovio's HPV DNA vaccine (VGX-3100) is intended to treat HPV as well as cervical pre-cancerous cell abnormalities and cancer. Cells transformed by HPV into cancer cells continue to express E6 and E7 proteins. Unfortunately, since this cell transformation can occur over 10 years or longer, the relatively slow proliferation of the HPV virus and these antigenic proteins could allow the immune system to become tolerant of their presence. VGX-3100 is designed to express the E6 and E7 genes from both HPV types 16 and 18. Using Inovio's proprietary electroporation technology, the vaccine is delivered into muscle cells of the patient. The principle of this mechanism is to enable these cells to produce these antigenic proteins in sufficient quantity that the immune system may recognize them, induce a robust T-cell response targeting the E6 and E7 proteins on HPV-infected cells, and cause those cells to be rejected from the body.

Source
Inovio Biomedical Corporation