RandyW Posted November 25, 2006 Share Posted November 25, 2006 Dogs have long been used for medical research, usually to the dismay of animal-rights activists. But now pet owners are enrolling their dogs in medical trials meant to benefit humans and animals alike. And some animal advocates are applauding the development. Most of the trials, often sponsored by drug companies or medical device makers, involve pets with cancer — a leading natural cause of death in older dogs — in which the animals receive groundbreaking drugs or other treatments that are eventually meant for people. The drug giant Pfizer has already introduced a human cancer drug that was given an early test in pet dogs, and a California company, IDM Pharma, recently filed for federal approval of another cancer drug that received similar testing. Treating dogs gives researchers an idea of whether and how the treatment will work in people, while at the same time possibly helping the pets. “It can help in reshaping the image of animals in science, from being considered tools to being considered patients,” said Martin Stephens, the vice president for animal research issues at the Humane Society of the United States. “And we would love to see that change.” The National Cancer Institute has set up a consortium of more than a dozen veterinary teaching hospitals to conduct the tests. The consortium has just completed its first study, with another to begin in a few weeks and several more planned for next year. Government and academic scientists are also now setting up a nonprofit group to study DNA and tumor samples from pet dogs, in an effort to pinpoint genes associated with cancer in both dogs and people. The government push is adding momentum to an approach in progress for several years among universities and medical centers that have been testing companies’ drugs and devices. Meanwhile, dogs whose owners enroll them in these trials often benefit from the best cancer treatments available. An exemplar of the trend is Basil, a 6-year-old golden retriever who sometimes wears a scarf reading “I’m a cancer survivor.” “They call him the miracle dog,” said Alan P. Wilber, a history teacher at a community college who, along with his wife, Kathy, lives with Basil in Los Banos, Calif. Basil developed bone cancer in 2001. By the time the affected leg was amputated, the disease had spread to 11 sites in his lungs and was deemed beyond surgical hope. But the Wilbers enrolled Basil in a study of a drug developed by Sugen, a biotechnology company, being conducted at the University of California, Davis. Enough tumors disappeared so that the rest could be removed surgically, and Basil has been free of cancer for three and a half years. Not all 57 dogs in the trial were as lucky as Basil, but the study “showed us the drug really worked, and it worked the way we thought it would,” said Julie Cherrington, who led preclinical research for Sugen at the time. In particular, the drug treated one type of dog cancer with the same genetic mutation as a human stomach tumor, she said. A very similar compound that Sugen developed for people went on the market early this year for the treatment of that stomach tumor and for kidney cancer. Pfizer, which now owns Sugen, says it hopes to get the animal version approved for veterinary use. Another company, Varian Medical Systems in Palo Alto, Calif., which makes equipment for radiation therapy, is sponsoring a dog study to test the theory that radiation can make certain cancer drugs more effective, an idea it also hopes to test in people. “At the same time as we are helping dogs, the dogs are providing information that is quite translatable” to human cancers, said Robert Sutherland, a Varian Medical executive. Cancer is not the only affliction of people and pets that could be eased by such an approach. Cyberkinetics Neurotechnology Systems, a medical device company, for example, hopes to begin selling a product to treat spinal cord injuries, developed at Purdue and tested there on injured pet dogs. But cancer, which the American Veterinary Medicine Association says accounts for nearly half of the deaths in dogs over 10 years old, is receiving special attention. Many veterinary centers are in a position to take part in such studies because they already offer — and many pet owners are willing to pay for — therapies once reserved for people. Dogs now get dental braces, hip replacements, kidney dialysis and brain surgery as well as brain and body imaging scans like C.T., M.R.I. and, yes, P.E.T. When the clinics enroll dogs in cancer trials, any drugs are typically provided free, although pet owners may have to pay for imaging and biopsies. Some pet owner groups say they welcome the trials because new treatments for dogs are needed. “We’re in dogs where humans were 50 years ago,” said Rhonda Hovan, research facilitator for the Golden Retriever Club of America. “When there’s a cancer diagnosis, it means death for the most part.” She said cancer accounted for 60 percent of all golden retriever deaths. While some veterinarians already use human cancer drugs “off label” to treat dogs, Ms. Hovan said, many pet owners cannot afford the $2,000 to $5,000 total cost for the drugs. And to avoid side effects, vets tend to keep doses low, limiting the drugs’ potency. Treatment is also limited in that there are only about 150 certified oncologists among the nation’s estimated 80,000 veterinarians. Researchers who conduct the trials on pets say the studies are approved by medical review boards, as with human clinical trials, and the owners must sign consent agreements. “These are essentially our patients,” said David M. Vail, director of clinical research at the University of Wisconsin’s veterinary school. “We’re not taking them into the back room and experimenting with them.” Some rules are lax for dogs, though. Studies of human drugs on dogs often do not need permission from the Food and Drug Administration. It is also easier to take multiple biopsies of dogs and to gain permission for autopsies after their deaths. Dog studies can also be shorter term; the saying that one year of a dog’s life equals seven for a person holds true for cancer’s development as well. “You are not waiting 5 or 10 years to determine something,” such as whether a drug prolongs survival, said Cheryl London, a veterinary oncologist at Ohio State University who conducted the Sugen trial while at the University of California. “It’s usually one or two years.” Dogs can also provide a valuable supplement to information from mouse studies. The history of the war on cancer is full of drugs that worked in mice but not in people. That is partly because the tumors used in mouse studies are somewhat artificial, often injected into mice whose immune systems have first been disabled. In pet dogs, as in people, the cancer arises spontaneously and the immune systems are functioning. Particularly useful are dog studies for cancers that are common in dogs but rare in people. There are about 10,000 cases a year of the bone cancer osteosarcoma in dogs, but only about 1,000 in people, mainly adolescents. Studying the disease in dogs thus gives researchers a larger sample. After a veterinarian showed in the 1980s that a drug called muramyl tripeptide could extend the lives of dogs with osteosarcoma, the National Cancer Institute began trying it in people. Last month, IDM Pharma, in Irvine, Calif., applied for approval to sell the drug, which it calls Junovan, for human patients. Researchers caution that pet dogs cannot totally replace mice and laboratory dogs. For one thing, drugs are generally tested for toxicity in young healthy animals, not old ones with cancer. Moreover, dogs do not contract many of the most common human forms of the disease, like lung cancer and, at least in the United States, breast cancer, Dr. London said, because dogs do not smoke and most American female pets are spayed. Colon cancer is also relatively rare in dogs. Some experts also say that results from dog drug trials might not be relevant to people because of differences in metabolism and genes. “You really have to design the medicine for the species of interest,” said Patrick M. O’Connor, head of oncology research for Pfizer. “You’ll find it very rare to find a medicine that will work in both.” That may be why some drug companies have been reluctant to get involved in pet dog trials. Another concern is that if a side effect was found in a dog, it could hurt the chances for a drug’s approval, even if the same side effect was not found in people. “I think the F.D.A. would be very understanding,” said Gregory A. Curt, a medical oncologist at AstraZeneca. “But this is all new and unexplored territory.” Chand Khanna, a veterinarian at the National Cancer Institute in charge of the new consortium set up to study drugs in dogs, said some of the trials planned were being done for pharmaceutical companies. (Information about the institute’s efforts with dogs can be found at ccr.cancer.gov/resources/cop.) One implication of such trials is that pets may have access to the most advanced technologies before people; they now rely on hand-me-down treatments developed for people. One example is a melanoma treatment developed at Memorial Sloan-Kettering Cancer Center in New York. For people, the treatment, called a vaccine because it spurs the immune system to attack cancer, is still in early clinical trials and it is too soon to say if it is working. But more than 350 dogs have already received it since 2000 under a collaboration between Sloan-Kettering and the nearby Animal Medical Center. Some of the dogs lived more than three years when they would have been expected to survive a few months, said Philip J. Bergman, head of oncology at the animal center. Merial, an animal health company owned jointly by Merck and Sanofi-Aventis, expects to receive conditional approval to begin selling the vaccine for dogs by the end of the year. As part of the drug trial, Kerri Schwartz — herself a veterinarian — has driven her terrier mix, Piggers, to New York from her home near Houston six times in the last year to get the injections. “This vaccine,” Ms. Schwartz said, “has to be responsible in large part for my dog still being here.” Quote Link to comment Share on other sites More sharing options...
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