Inovio Pharmaceuticals, Inc. announced that its subsidiary VGX Animal Health, Inc., a developer of DNA-based vaccines and therapies for companion and food animals, has achieved strong T cell responses from VAH-5000D, its DNA vaccine encoding telomerase reverse transcriptase (TERT) for the treatment of dogs with cancer. This preclinical data was presented by Dr Douglas Kern, DVM, VGX Animal Health's vice president of business development, at VetHealth Global 2011, an international animal health conference.
In mouse experiments, vaccinations with a highly optimized TERT DNA vaccine delivered by electroporation induced strong TERT-specific T cell immune responses. Furthermore, vaccination with the TERT vaccine delayed the growth of implanted tumours in mice and increased the survival rate of mice with tumours.
"We are pleased to see promising results in animal trials with our optimized TERT vaccine for dogs," said Dr Kern. "Because of the prevalence of TERT in tumours, we believe that a canine specific TERT vaccine could become the go-to 'universal' cancer vaccine for dogs."
TERT is a catalytic subunit of the enzyme telomerase. Telomerase lengthens telomeres, which are structures at the end of chromosomes (DNA strands in the nucleus of all cells). Telomeres protect the ends of chromosomes from destruction and normal cell death. The mammalian cell divides anywhere from 60-100 times throughout its life cycle. Each time this division occurs, telomeres are shortened until they no longer serve to protect the chromosome. This is the basis for the aging process in mammals. When telomerase begins to function abnormally, the cell can become immortal. This process is thought to be important in the development of several types of cancer. Human TERT (hTERT) has been proposed as a cancer-specific target, since it is almost exclusively over-expressed in tumour tissue compared to normal tissue in humans, i.e. 85% of the time its presence is in tumours. There is no other tumour-associated gene that is as widely expressed in cancers.
Therapeutic vaccines directed against the crucial telomerase protein TERT offer the potential to stimulate the rapid killing of tumour cells by enhancing the activity of telomerase-specific T cells. Such vaccines are being tested in human trials in leukaemia and renal, prostate, lung, skin, pancreatic and breast cancer. For instance, Merck has licensed Inovio's electroporation delivery technology to deliver its DNA vaccine encoding hTERT in an ongoing phase I clinical trial. Inovio is in preclinical development of its more optimized SynCon hTERT DNA vaccine candidate for treating human cancer targets. VGX Animal Health is developing its canine-specific TERT DNA vaccine product, VAH-5000D, for the treatment of dogs with cancers.
VGX Animal Health is developing DNA-based vaccines and therapies for companion and food animals utilizing proprietary plasmid-based DNA delivery and expression technology to optimize an animal's natural biological and immunological potential. The company is a majority-owned subsidiary of Inovio Pharmaceuticals, Inc.
Inovio is developing a new generation of vaccines, called DNA vaccines, to treat and prevent cancers and infectious diseases.