Good News On Head And Neck Cancer

A virus that has been genetically engineered to home in on and destroy cancer cells has shown strong and lasting effects against tumors in patients when combined with standard chemotherapy.

CBS News Health Correspondent Dr. Emily Senay reports the treatment shrank tumors in almost 85 percent of patients and completely got rid of the tumors in some of these patients.

It will take years for the therapy to be approved by the Food and Drug Administration.

Unlike other types of gene therapy, this treatment does not repair damaged genetic material.

Instead, it is based on a modified cold virus that only kills cells that are cancerous by detecting a genetic flaw.

Researchers say 25 out of 30 patients with head and neck cancer saw their tumors shrink after they were treated with Onyx Pharmaceuticals Inc.'s ONYX-015 along with chemotherapy.

Eight tumors disappeared, Dr. Fadlo Khuri and colleagues at M.D. Anderson Cancer Center in Houston, working with teams in Britain, wrote in the journal Nature Medicine.

"ONYX-015 may be able to sensitize infected and uninfected cells to killing by chemotherapy," they wrote.

"It is very encouraging because this is the first time there has been a Phase II trial -- a trial with more than just a few patients in it -- where the tumors have gone away in a significant number and they haven't come back," gene therapy pioneer Dr. William French Anderson of the University of Southern California said.

"There are lots of Phase I trials where you get tumors to go away but they come back."

Phase I trials are only to find out if a treatment is safe and involve very few people. Phase II trials involve more people but volunteers are often critically ill because safety is still being assessed. Phase III trials involve a larger number of people and are the final phase aimed at determining whether a treatment or drug actually works.

Every year, 500,000 people worldwide are diagnosed with cancer of the head and neck, and about 30 percent of them die. Such cancers, heavily associated with the use of alcohol and tobacco, are treated at first with surgery, radiation therapy or both.

But tumors come back in about a third of patients. When this happens, the outlook is grim.

Doctors have tried chemotherapy, but it makes patients ill and does not seem to help them live any longer.

Gene therapy is a possible new approach.

Anywhere between 45 and 70 percent of head and neck tumor cells have mutations in a gene known as p53, which, when normal, helps repair cancer-causing damage.

ONYX-015 is an adenovirus, a relative of common cold viruses, that has been genetically engineered to attack cells that lack normal p53.

This makes it technically a gene therapy drug, although unlike other gene therapy approaches ONYX-015 does not repair or replace a faulty gene, Anderson said.

Last year ONYX-015 sowed remarkable effects in head and neck cancer patients, but the effects did not last for long.

Khuri's team combined ONYX-015 with two common cancer chemotherapy drugs -- 5-FU and cisplatin -- to see if it would help them work better.

"Treatment caused tumors to shrink in 25 of the 30 cases evaluated," Khuri's team wrote in their report.

They said only 17 percent of tumors had progressed 6 months after treatment -- which meant the combination of gene therapy and chemotherapy worked better than any treatment alone.

There were side-effects.

"A substantial minority of patients reported some flu-like symptoms, including fever (34 percent), asthenia (weakness -- 47 percent) and/or chills (24 percent)," the researchers wrote. But they said no one stopped the treatment because of them.

The approach has one weakness: ONYX-015 has to be injected directly into the tumor to work. These means it is of no apparent use against tumors that are not easy to reach, or against tiny tumors that cannot be seen yet.

The researchers said most of their patients eventually died of their cancer -- because other, untreated tumors in their body spread.

"If all tumors are injected in future trials, the clinical benefit to and length of survival in patients may be improved further," Khuri's team wrote.

They also suggested it might be possible to give ONYX-015 to patients intravenously, which would affect the whole body.

Anderson said the experiment was one of several that was helping rehabilitate the troubled field of gene therapy.

"With all its twists and turns, gene therapy seems to be turning the corner after a very bad year," Anderson, who conducted the first gene therapy experiment in 1990, wrote in a commentary.

He noted that French scientists had used gene therapy to cure two baby boys of a rare, inherited immune disorder called severe combined immunodeficiency, and said there had been successes against hemophilia, heart disease and now cancer.