Saltzman says he has applied for 11 grants. One was rejected, one was awarded for $30,000, and he’s awaiting responses on the rest. This isn’t his first effort to prove the salmonella concept. He got a $375,000 grant from the National Cancer Institute a few years ago and has won support from several smaller funds. All told, he said, he has spent $125,000 to $250,000 a year on the project in the last 13 years.
Saltzman, who is both an M.D. and a Ph.D., said he got interested in using salmonella to fight cancer in 1993. He was working in a lab with Interleuken 2 (IL2), which boosts the immune system but is extremely toxic. He and his mentor attended a meeting on vaccines one day and learned about salmonella, which lodges in the liver and reproduces. They wondered whether it could be used to deliver IL2 to fight liver cancer.
A famous microbiologist named Roy Curtiss, now at Arizona State University, gave them permission to use a nontoxic strain of salmonella he’d developed. A cocktail combining salmonella and IL2 reduced liver cancer tumors in mice by 60 percent. Then Saltzman’s group and a group at Yale University learned that salmonella also has a strong affinity for cancerous tumors throughout the body, and the race was on to use it to kill them. A company founded by the Yale team went bankrupt. Saltzman said his research showed good results in dogs but failed to produce “a survival advantage” in humans.
Then about three years ago, new research showed that cancer cells produce a force field around themselves that prevent attack by chemotherapy or the immune system. Saltzman re-engineered the modified salmonella so that it would carry a number of immune-boosting proteins. Initial tests indicate that it defeats a tumor’s force field.