March 30, 2001--Targeted Genetics Corporation (Nasdaq:TGEN - news) today will announce promising data from preclinical studies utilizing recombinant adeno-associated virus (AAV) vectors as a form of vaccination. Data will be presented by Philip R. Johnson, M.D., President of the Children's Research Institute on the campus of Columbus Children's Hospital, and Professor of Pediatrics, College of Medicine and Public Health, The Ohio State University, at the Keystone Symposium on AIDS Vaccines in the New Millennium, held in Keystone, Colorado. Targeted Genetics is collaborating with Dr. Johnson and the International AIDS Vaccine Initiative (IAVI) on the development of an AAV-based AIDS vaccine.
In a presentation to be delivered this evening, Dr. Johnson will review the results from preclinical studies of an AAV-based vaccine designed to protect against infection by SIV, the monkey equivalent of HIV. In these studies, monkeys received the vaccine by injection into muscle. Following a single injection of the vaccine, the monkeys exhibited strong and durable antibody and T-cell responses that persisted for over a year in all monkeys studied. When these animals were challenged by intravenous injection with highly virulent infectious SIV, they had ten-fold fewer detectable particles of the virus in the blood compared to controls. In a second experiment, the peak level of SIV in the circulation was reduced almost a 1000-fold when animals were given a priming dose of a naked DNA vaccine several weeks prior to receiving a booster immunization composed of the AAV-based vaccine. Additionally, AAV-based vaccines appear to have a good safety profile, with no untoward effects observed in mice and monkeys studied for two years or more. These studies were funded by the National Institute of Allergy and Infectious Diseases.
``AAV vectors have been shown in a number of clinical and preclinical studies to deliver genes to a variety of tissues, to express genetic information effectively for long periods of time and to have a good safety profile,'' said Dr. Johnson. ``These attributes make AAV an attractive vector to use for genetic immunization. The data from these studies are quite promising, particularly when the AAV-based vaccine is delivered following administration of a naked DNA vaccine. We believe that an AAV-based vaccine may enable the development of a ''prime-boost`` vaccination strategy that could be delivered as a single injection. This is because there is a two to three week lag between the time that an AAV vector introduces genetic information into a cell and detectable expression of that genetic information. Thus, delivering naked DNA and AAV-based vaccines simultaneously may provide the enhanced protection of the prime-boost approach in a single injection, which could be delivered in a more time-effective, cost-effective and patient-friendly manner.''
Based on Dr. Johnson's work in the area of AAV-based AIDS vaccines, Targeted Genetics' expertise in AAV vector manufacturing and IAVI's mission to support the development of an effective AIDS vaccine, the three parties entered into a collaboration in February 2000. ``We are excited about these data and are moving forward in developing tgAAC-09, our AAV-based AIDS vaccine,'' said Pervin Anklesaria, Ph.D., Vice President, Research at Targeted Genetics. ``The ability of AAV-based vaccines to induce both neutralizing antibodies and killer T-cell responses should translate into protection against SIV infection. The significant reduction of peak viral load observed in Dr. Johnson's studies is very encouraging and supports further preclinical and clinical testing of the naked DNA prime/AAV vector boost strategy for HIV vaccines. The potential to combine a DNA prime with an AAV boost into a single injection makes this approach somewhat different than other strategies, which require multiple injections over an extended period of time. To truly impact the global HIV/AIDS epidemic, a vaccine must address the constraints of developing nations, where repeat administration is not practical. The stability of AAV vectors and our ability to manufacture large-scale quantities of these vectors in a cost-effective manner are additional factors that make an AAV-based AIDS vaccine a promising approach to addressing the global HIV crisis.'' ..... |
