Future Tech
Mouthwash Might Treat Cancer
Matthew Herper, Forbes.com, 05.18.01, 12:30 PM ET
NEW YORK - Can a mouthwash squash cancer? Maybe, if it`s swarming with tiny viruses that unleash a powerful gene therapy on pre-cancerous cells while leaving healthy tissue alone.
Onyx Pharmaceuticals (nasdaq: ONXX - news - people) presented results of a clinical trial on such a product this week. The "mouthwash" is actually a saline solution filled with the Richmond, Calif., company`s lead product: a virus genetically engineered to attack cells as they become cancerous.
Cells in the mouth turn into cancer tumors only when their genes are heavily damaged, often through heavy use of tobacco or alcohol. This damage doesn`t occur all at once; before tumors appear, lesions show up in the form of red or white patches. The virus should kill these pre-cancerous lesions before they metastasize into cancerous tumors.
Adenovirus gives people colds. Could sloshing a genetically tweaked version in your mouth fight cancer before it happens?
In the recent clinical trial, ten patients who had pre-cancerous lesions in their mouths rinsed with the flavorless solution for half an hour, once weekly for three months. Those that showed improvement were eligible for another three months of treatment. Doctors took biopsies of the tissue to see if it became more or less cancerous.
Two of the ten patients saw patches completely disappear, one for nearly six months. The lesions became less severe in two others and got worse in the rest of the patients. This was a Phase II study, which means it was not aimed at proving conclusively that the treatment works.
The mouthwash was not toxic, although Onyx Senior Vice President of Corporate Development Helen Kim says some patients experienced minor flu-like symptoms, including chills and low fevers. That`s not surprising, given that Onyx`s cancer-fighter is a modified adenovirus, the same bug that causes the common cold.
Swishing with the mouthwash won`t cure cancer after it occurs, because the adenovirus can`t bind to the surface of tumor cells, says David Bouchey, an analyst at New York-based C.E. Unterberg, Towbin. He calls the results promising, although he says much still needs to be proved.
It`s even possible that it`s an immune response that halts the cancer, not the viruses killing cancerous cells. Bouchey doubts an important selling point for the Onyx virus--that it only attacks cells in which a protein called p53 is defective. This defect is common in cancer cells, but not in healthy ones. The company insists that further research has shown the virus does indeed target only cancer cells with defective p53.
Bouchey is bullish on the mouthwash. But he recently lowered his rating on the stock from "neutral" to "avoid" because he thinks the company`s near-term product, an anti-cancer gene therapy that is injected into the body and is being co-developed by drug giant Pfizer (nyse: PFE - news - people), will be too cumbersome for doctors and patients alike.
In 2000, Onyx posted a loss of $7.5 million on revenue of $24.2 million. But it is partnered with deep-pocketed Pfizer and has $82 million in cash and short-term investments that could probably be used to fund further research and clinical trials for some time.