Slightly human mice test cancer drugs
BALTIMORE – Megan Sykes, a medical researcher, has a mouse with a human immune system — her own. She calls it “Mini-Me.”
There are also mice containing a part of nine-yearold Michael Feeney — a cancerous tumour extracted from his lungs. Researchers have tested various drugs on the mice, hoping to find the treatment that would work best for Michael.
In what could be the ultimate in personalized medicine, animals bearing your disease, or part of your anatomy, can serve as your personal guinea pig, so to speak. Some researchers call them avatars, like the virtual characters in movies and online games.
“The mice allow you the opportunity to test drugs to find out which ones will be efficacious without exposing the patient to toxicity,” said Colin Collins, a professor at the University of British Columbia.
Experiments on mice have been done for decades, including implanting people’s tumours into the animals. But the techniques have improved in the last few years and interest is growing. While the models are mainly used for research, companies are beginning to commercialize them for use in drug development and medical treatment as well.
Experts caution that it has not been proved that the use of avatars will prolong the lives of cancer patients. And it costs tens of thousands of dollars, which insurers will not cover, to create and test a colony of the animals.
“It’s an act of faith to say this is a superior way of proceeding,” said Dr. Edward Sausville, an expert on mouse models of cancer at the University of Maryland. But some cancer patients, wanting to try everything possible, are turning to the mice anyway.
“This just seems right to us,” said Jill Feeney, the mother of Michael, who has been fighting a type of bone cancer called Ewing’s sarcoma since he was six. “It’s actually his tumour growing somewhere, and we’re treating it the way he would be treated.”
When Michael had surgery in February to remove a tumour that had spread to a lung, a courier was waiting outside the operating room in New York to whisk the tumour to a Baltimore laboratory run by a company called Champions Oncology.
Four hours later, technicians cut the tumour into five pieces and placed each piece under the skin of an anesthetized mouse. Two months later, after the tumours had grown, they were removed, cut into pieces and each piece implanted into another mouse. A month later there were enough mice models to begin testing.
The Feeneys, who live in Ridgewood, N.J., paid $25,500 for the creation of the avatars and the testing of four different drugs or drug combinations.
The results came back in July. A combination of four drugs — gemcitabine, docetaxel, Avastin and Afinitor — was “astonishingly active” in shrinking the tumour in the mice, said Michael’s oncologist, Dr. Leonard H. Wexler of the Memorial Sloan-Kettering Cancer Center. Wexler said that the combination was not something oncologists would typically choose.
Michael has not tried the combination yet because he is participating in a clinical trial of an experimental drug. But if that drug does not work, his mother said, “we have the home run in the back pocket.”
Skeptics say randomized trials are needed to prove patients using avatars will fare better than they would have otherwise.
Some experts say that testing a tumour for genetic mutations is a far more practical way to figure out which drug may work best. But that does not always yield a useful result. Nir Toib, an Israeli filmmaker with lung cancer, said treatments suggested by a genetic analysis of his tumour did not work, but that a combination of two drugs suggested by the avatar testing did.
“I had 10 tumours on my right kidney,” Toib said. “All of them disappeared.”
While Toib joked that he had himself “cloned” in the mice, neither he nor most other patients feel any personal attachment to their mice.
Feeney said Michael “was a little upset to hear we would be giving mice cancer and that we might kill them.” But if Michael is saved by a treatment resulting from testing on his avatars, she said, “I will love these mice forever.”