A new gene therapy has helped pet dogs with cancer live longer and could potentially improve the quality of life and survival of people with cancer, said the therapy's developers. The results of the animal study will be presented at The Endocrine Society's 90th Annual Meeting in San Francisco.
The single treatment works by increasing muscle strength and correcting common complications of cancer such as weakness, weight loss and anemia, said principal investigator Ruxandra Draghia-Akli, MD, PhD, researcher, VGX Pharmaceuticals Inc., The Woodlands, Tex.
Such complications occur in more than 50 percent of patients with cancer and, along with loss of appetite and fatigue, result in poor quality of life, she said. If cachexia—muscle wasting and severe weight loss—develops, it can prevent cancer-specific therapy from being given and may be a direct cause of death.
"With our type of gene therapy," Draghia-Akli said, "we can 'trick' certain types of cells in the body to naturally produce specific hormones." These hormones have a muscle-building, or anabolic, effect.
The therapy uses a nonviral DNA molecule, called a plasmid, which encodes for growth hormone-releasing hormone (GHRH). This stimulates the endogenous growth hormone and another growth substance, insulin-like growth factor-1 (IFG-1), which have anabolic effects.
The therapeutic process involves injecting the DNA fragment into a muscle and applying electroporation—short, mild, controlled electric fields—in the area of the injection. It opens the cell membrane pores and traps the DNA inside the cells, which allows the production of GHRH. This thwarts the body's natural process of eliminating a foreign body, in this case the DNA molecule, Draghia-Akli explained.
The researchers tested the gene therapy in 55 companion dogs that had cancer and anemia and were receiving cancer treatment. Three months after the injection, 54 percent of the dogs had responded to gene therapy, as apparent on blood testing. Dogs that responded to therapy survived 84 percent longer, compared with dogs that did not respond to gene therapy and untreated control dogs that received a placebo injection. Although the response rate dropped to 47 percent at 4 months, it was still 22 percent higher than in control dogs.
Also, study data showed quality of life, especially appetite, dramatically improved with the gene therapy, and complications of chemotherapy, such as vomiting and diarrhea were greatly reduced,
VGX Animal Health Inc. plans to develop this product for companion dogs and cats. VGX Pharmaceuticals Inc. is also waiting for approval from the Food and Drug Administration to study the GHRH treatment in humans with cancer cachexia, Draghia-Akli said.
Founded in 1916, The Endocrine Society is the world's oldest, largest, and most active organization devoted to research on hormones, and the clinical practice of endocrinology. Today, The Endocrine Society's membership consists of over 14,000 scientists, physicians, educators, nurses and students in more than 80 countries. Together, these members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Maryland. To learn more about the Society, and the field of endocrinology, visit our web site at www.endo-society.org.
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