A new weapon to fight cancer – tobacco plants

August 22, 2008

By hammersmith

[Source: Ken Alltucker, The Arizona Republic] – Tobacco is better known as a cause of cancer rather than a potential cure.

But scientists in Arizona and elsewhere believe tobacco plants may hold the key to developing a personalized cancer vaccine as well as treatments for other diseases.

The experiments are part of a growing field of plant-based biotechnology, and the cancer treatment has gained enough traction to interest the likes of German drug giant Bayer.

“Most important is that the vaccine has been successfully used in human clinical trials,” said Charles Arntzen, director of the ASU Biodesign Institute’s Center for Infectious Diseases and Vaccinology.

The made-to-order vaccine has been tested in an early-stage clinical trial, and it showed an immune response in 70 percent of non-Hodgkin’s lymphoma patients without harmful side effects.

Even though it is called a vaccine, it will not prevent a person from getting non-Hodgkin’s lymphoma, which is the seventh-leading cause of cancer-related deaths in the United States. Rather, the vaccine is made from a person’s diseased cells and programmed to attack that individual’s cancer.

Bayer has spent nearly $15 million on a facility in Germany that initially will grow the tobacco plants to make personalized vaccines for lymphoma patients. The German drug manufacturer plans to explore treatments for other diseases, too.

“It is a huge investment by a company to gamble that they will make it through clinical trials,” said Arntzen, who wrote about the personalized plant-based vaccines in an article published Thursday in the journal Science.

Arntzen said he has collaborated with scientists at Stanford University who are developing plant-based vaccines. Earlier this year, the Biodesign Institute secured a $1.5 million grant from the federal government to study whether tobacco plants can yield a vaccine that blocks the West Nile virus from attacking a person’s central nervous system. It is a similar technology that is being studied and used by Bayer and Stanford researchers, Arntzen said.

Although scientists are excited about the prospect of using plants to develop individual cancer treatments, no one has yet estimated how much such personalized treatments would cost to make.

Plant-based biotechnology already has been used to produce drugs for diseases such as cystic fibrosis and Gaucher’s disease, but some of these personalized drugs can be pricey for consumers.

Avastin, a cancer drug made by South San Francisco-based Genentech, can cost up to $8,800 per month, and Genzyme’s Cerezyme, which is used for Gaucher disease, costs about $200,000 a year.

Experts say drug development increasingly is shifting from a one-size-fits-all approach. Drug manufacturers realize that personalized drugs hold great promise as being more effective with fewer side effects. Yet producing such individualized drugs can be expensive and fraught with regulatory challenges.

It would be tough to replicate such a personalized drug in a manner consistent enough to pass muster with the Food and Drug Administration.

“It is going to take some innovative methods to generate that kind of product,” said Ray Woosley, president and chief executive officer of the Tucson-based Critical Path Institute, which works to make the drug-development process quicker, safer and more effective.

“It is going to be a challenge to have that kind of individuality and to make sure you produce it the same way (to pass the FDA’s review),” Woosley said.

How it works

Bayer envisions a personalized vaccine that is made based on a patient’s unique genetic makeup. The vaccine is produced by taking DNA from a person’s cancer cells, genetically modifying the DNA strands and transferring the virus to a tobacco plant. The plant responds by producing a protein that can help a cancer patient battle the disease.

The plant-based vaccine works by prodding a person’s immune system to attack cancer tumors.
Other scientists have explored the possibility of using animals to make the vaccine, but the tobacco-plant vaccine can be produced much more quickly.

Indeed, speed is a key to growing these personalized treatments.

Scientists estimate that such vaccines can take just six to 10 weeks to produce from the time of a patient’s biopsy. That would give doctors a quick time frame to administer the vaccine rather than revert to traditional cancer treatment such as chemotherapy, which has harmful side effects.

Arntzen said that non-Hodgkin’s lymphoma is a relatively low-moving cancer, so it gives researchers time to grow, cultivate and give the vaccine to patients.