Dogs with cancer in the US are now entitled to receive experimental drugs – before the drugs are available for humans. Twelve trials are under way on groups of 15 to 60 dogs, and in several of them cancers have disappeared.
"We've had dramatic remissions in dogs with really aggressive cancers," says Chand Khanna, head of the Comparative Oncology Trials Consortium newly formed in Bethesda, Maryland, by the US National Cancer Institute. "We've also had responses allowing dogs to have their original cancers surgically removed," he says.
Forget mice and rats
The rationale is that unlike mice and rats, which are kept in a highly regimented experimental setting, pet dogs experience cancer in a similar way to humans. As in people, cancers in dogs spread to form secondaries and can become resistant to drugs, and the animals can have relapses.
Not only that, but dogs suffer from cancers as variable as those affecting humans, so treating them gives us a much better idea of what would happen in a cross-section of humans than we could gain from lab studies of mice.
The consortium consists of 19 veterinary schools, and there are plans to extend it to Europe. Owners can opt for conventional drugs or experimental ones, including some that are untested in humans and others that are already undergoing trials, but that need additional animal data – for example on dosing – before they can proceed to the next stage.
As well as looking after their sick dog, owners can help gather data for the researchers. "They're given notebooks so that they can complete assessments of quality of life, appetite, demeanour and perhaps even collect some specimens," says Khanna.
Because owners carry on caring for the dogs, and because the hope is that pet dogs will get better as a result of the treatment, the approach also challenges claims by antivivisectionists that all experimentation on animals is wrong. "I understand their sensitivities, and we've had informed discussions with individuals, and some do see the value of helping dogs with cancer in this way," says Khanna.
"This raises serious concerns with respect to what the dogs may have to endure," says Nedim Buyukmihci, a vet consultant to the British Union for the Abolition of Vivisection.
Every dog matters
Khanna says, however, that the top priority for every dog is their well-being. "It's important that the trials are designed with the care of the animals as priority, and also that there's an informed consent process each time," he says.
Cancer researchers in Europe are watching closely to see whether to join the consortium. "Studying dogs, with their owners' consent and following ethical guidelines, after they have naturally developed cancer, is an interesting approach to learning more about the disease," says Joanna Owens, communications manager at the Cancer Research UK charity in London. "We look forward to following the progress of this initiative and the findings that come out of their research."
Journal reference: PLoS Medicine, DOI: 10.1371/journal.pmed.1000162 (in press)
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