57 percent of the subgroup of smokers who had developed a high antibody response to the vaccine had stayed off cigarettes continuously at 24 weeks. 'This is highly significant. This clearly suggests that antibodies against nicotine are helpful for people trying to quit smoking.'

Nicotine Vaccine Shows Promise

Swiss researchers have reported initial positive results with an experimental nicotine vaccine that might help smokers quit.

The trial did not find a statistically significant difference in quit rates between the vaccine group and a group of smokers taking a placebo, but it did report higher quit rates in a subgroup of smokers who had developed a high level of antibodies in response to the vaccine.

"It's a proof of principle that the development of an antibody response can be associated with a drop in smoking," said Dr. Joshua Ellenhorn, a surgical oncologist and cancer vaccine researcher at City of Hope Cancer Center in Duarte, Calif. "It begs the question, are they able to come up with a better vaccine or one given in a different regimen that would put a higher number of patients in the high antibody-response group, and give a higher number of patients the possibility of quitting.

"None of the other vaccines have shown that there's real potential for efficacy, and it correlates with a marker suggesting that here's a real reason for the efficacy," Ellenhorn continued. "From a scientific point of view, it's very novel and interesting, and potentially very exciting. From the point of view of direct applicability and marketability, it is clearly far from that."

"It's proof of efficacy," agreed Thomas J. Glynn, director of International Tobacco Programs at the American Cancer Society. "This alone is not going to change the face of tobacco. It's going to help."

Wolfgang Renner, CEO of Cytos Biotechnology AG of Zurich, Switzerland, which is developing the Cytos002-NicQb vaccine, said that if other trials go well, the product could hit the market in 2010.

After the presentation of the study results Saturday at the annual meeting of the American Society of Clinical Oncology in Orlando, Fla., Renner was mobbed by financial analysts, indicating that the first effects of the nascent vaccine are likely to be felt in the financial markets and not in any health-care setting.

The market for such a vaccine is huge, with some 50 million people in the United States alone continuing to smoke. The habit is a factor in a litany of diseases, and is the number one preventable risk factor for cancer. "The impact of tobacco on illness remains a substantial health problem in the world," confirmed Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society.

A vaccine for nicotine, many feel, could be the answer doctors and smokers have been hoping for; this is only one of several pharmaceutical products that are in the pipeline, Glynn noted. Two other vaccines are NicVAX, which is in Phase II trials, and TA-NIC. Varenicline and Rimonabant (not vaccines) have reported about 50 percent quit rates at 12 weeks, and may be approved by the U.S. Food and Drug Administration within a year.

Dr. Jacques Cornuz of Centre Hospitalier Universitaire Vaudois in Lausanne, Switzerland, who presented the findings, said the vaccine reduces the amount and rate of nicotine entering the brain. This interferes with the "reward" system of the brain and reduces the incentive to keep puffing.

A Phase I trial for the vaccine involving 40 healthy non-smokers found the vaccine was safe, and that all individuals developed antibodies.

The Phase II trial discussed Saturday involved 341 heavy smokers (average habit of 25 cigarettes a day for 25 years) who were randomly assigned to receive either the vaccine or a placebo. They were asked to make a serious attempt to quit smoking four weeks after the first of five doses. Participants' smoking status was assessed at four, five and six months after the first vaccination.

After four weeks, 40 percent of the vaccinated group had been continuously abstinent vs. 31 percent of the placebo group, which was not a statistically significant difference, the researchers said.

However, 57 percent of the subgroup of smokers who had developed a high antibody response to the vaccine had stayed off cigarettes continuously at 24 weeks. "This is highly significant. This clearly suggests that antibodies against nicotine are helpful for people trying to quit smoking," Cornuz said. "The vaccine achieves long-lasting antibodies which may protect against relapse."

Also, people in the vaccine group who were still smoking were smoking less.

The study results signify how far the market for budding quitters has come.

"I think the real news is that there's this whole new array of tools available to smokers," Glynn said.

More information: For more on quitting smoking, visit the American Lung Association.