Research scientists at Johns Hopkins University are refining a novel method to fight cancer using targeted injections of a soil-dwelling bacteria.
Clostridium novyi, a bacteria commonly found in soil and feces, subsists on living cells by releasing an alpha-toxin protein that breaks down the structural integrity of cells. As a result, these infected cells begin leaking vital fluids and organelles into the surrounding tissue, which the C. novyi bacteria then feast on. Cancer geneticist Bert Vogelstein of Johns Hopkins University in Baltimore, Maryland, and his colleagues have been working on refining the use of C. novyi against tumor cells for the better part of a decade.
The idea of using bacteria to kill cancer cells has been around for more than 200 years. New York City surgeon William Coley was the first to propose the use of bacteria as an alternative treatment against cancer in the 1890s. Although his first two attempts to treat patients using live Streptococcus bacteria ended in their deaths, he was able to successfully treat more than 1000 patients with injections of dead bacteria in either the tumors themselves or in the bloodstream. As the rise of chemotherapy, radiation, and surgery became popular, Coley’s unique treatment was quickly lost to the history books. Fortunately, a 1999 reanalysis of his work discovered that his success rate was relatively equal to the success rate of contemporary treatment options.
Inspired by Coley’s work and the reexamination of his documents in 1999, modern researchers began experimenting with a variety of bacteria, among them weakened strains of Salmonella, to see if Coley’s work could be improved upon and made more effective. So far, Dr. Bert Vogelstein’s use of C. novyi bacteria seem to be yielding the best results.
According to Saurabh Saha, a cancer researcher at BioMed Valley Discoveries Inc. in Kansas City, Missouri, tumors are oxygen poor, creating an environment in which bacteria like C. novyi love to reside. It’s also why these bacteria do not risk harming patients. After depleting the tumor, the moment the bacteria make contact with the oxygen rich bloodstream, they begin to die.
After tests on animals have proved safe and effective, researchers have now begun testing C. novyi on humans with equally promising results. The first patient to be tested received an injection of the bacteria into a tumor growing in her shoulder. Even though the dose was less than 1% in strength than what was given to animals, the patient’s tumor decreased significantly. Since the patient only received localized treatment, she nonetheless past away due to late stage cancer cells that were present throughout her body.
Although the efficacy of C. novyi is limited to direct injections, and no systemic version currently exists, researchers are hopeful that their research will expand to include wider, systemic treatment that extends beyond targeted injections.
Douglas Thamm, a cancer biologist and veterinary oncology researcher at Colorado State University’s Flint Animal Cancer Center in Fort Collins, says these early human trials are “proof of the concept that this particular approach can have antitumor activity in real tumors.”
(Illustration by Katie Vicari)
(Featured image: breast cancer cell)