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Oxigene Breathes Life into Cancer Treatments
volume 6 | issue 8
August 2007Page 1163
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The potential study subjects for Oxigene Inc.'s Zybrestat, now undergoing human trials for treatment of anaplastic thyroid cancer, are eager for enrollment.
But all too frequently, a call-back reveals the malignancy of the drug's foe: Would-be patients in the Phase II/III study are dying before they ever get near one of the 45 sites around the world that are testing the drug.
"This is really one of the worst cancers," said Dr. Richard Chin, president and CEO of Oxigene. "It goes really quickly and there is nothing out there that can help them."
Zybrestat, the company's name for combretastatin-A4 phosphate, or CA4P, is a small-molecule vascular disrupting agent. Taken intravenously, the CA4P interacts with vascular endothelial cell cystoskeletal proteins and effectively cuts off the blood supply to cancerous tumors.
CA4P is based on an extract of the African bush willow, one of the last in a mass screening of natural drugs by the National Institutes of Health, Chin said. The U.S. Food and Drug Administration in 2003 awarded orphan drug status to CA4P for the treatment of anaplastic thyroid cancer, medullary, Stage IV papillary and Stage IV follicular thyroid cancers. The orphan drug designation gives Oxigene a seven-year monopoly for treating these cancer types.
Oxigene estimates that approximately 58,000 people in the United States have one of these four types of cancer.
"The good news is, this drug works very fast - within minutes," Chin said. "In animal models, you can literally see the blood flow just stopping. It's a physical collapse of blood vessels, and that happens quite quickly."
Initial results from the trials appear promising. The life expectancy for anaplastic thyroid cancer is only three months, and several patients have lived twice as long, or even longer. One test subject from a 1999 trial is in complete remission and surviving, Chin said. Should CA4P live up to its promise, Oxigene has a few options when it comes to marketing it. Since the consumer need is quite small, the company could continue to develop it on its own, or it may turn to a larger pharmaceutical company, Chin said.
"We don't have to, but in biotech right now, big pharma is desperate for new drugs and they offer terms you really can't turn down," Chin said.
Cancer treatments have changed over the last decade. Researchers are trying to find alternatives to chemotherapy, which causes extensive side effects, and create treatments directed solely at abnormal cells.
"We now know a lot about the different kinds of tumors, what they need to survive, what they need to grow," Chin said. "This doesn't cause hair loss, the ulcers in the mouth, it doesn't create the traditional chemotherapy effects. It's very well tolerated.
"It's still a risky proposition," Chin added. "Of all the new drugs that start in clinical trials, only a few get to the end. We're very confident at this stage - if the drug works, it's going to help a lot of people."
Oxigene is also in a Phase II trial of CA4P in fighting a form of advanced macular degeneration, in which there is abnormal blood vessel growth in the choriocapillaries. Current drug treatments must be injected directly into the eye and Oxigene's version is as well, but they have high hopes that the treatment would be effective in eye-drop form.
"Stick a needle in the eye once a month - if you had to create a worst way to administer anything, sticking a needle in the eye would be it," Chin said. "Somehow, I think an eye drop would be welcome."
For more information contact: Jennifer Lord; Tel.: 508-626-3880 or jlord@cnc.com