« Prev Next »
One hundred years ago, a surgeon in New York City named William Coley injected cancer patients with dead Streptococcus bacteria to help eradicate their cancer. He administered his ‘Coley toxins' to more than 1000 patients, injecting dead bacteria into tumors and bloodstreams. Many of his patients survived. But as new techniques such as radiation and chemotherapy arrived, the Coley toxins - even though their success rates came close to those of modern cancer therapies - became the stuff of history books.
"One advantage of using bacteria to treat cancer is that you can modify these bacteria relatively easily, to equip them with other therapeutic agents, or make them less toxic as we have done here, " said Shibin Zhou, M.D., Ph.D., associate professor of oncology at Johns Hopkins Medicine.
According to this study, these researchers demonstrate that this form of cancer therapy using C. noyvi-NT might actually work to combat tumors. Oxygen is scarce inside tumors, and these bacteria "love areas of low oxygen," says Saurabh Saha, a co-author on the study. "They grow and divide and kill the cancer cells," Saha says. "A good thing about using bacteria as a therapeutic agent is that once they're infecting the tumor, they can induce a strong immune response against tumor cells themselves." The researchers hypothesized that the bacteria release enzymes that destroy the tumor cells, and eat the shreds.
To start testing their hypotheses, the Johns Hopkins team injected bacterial spores directly into rat tumors with brain cancer. They observed an antitumor response that improved the survival rates of the animals.
They moved on to test dogs. "One of the reasons that we treated dogs with C. noyvi-NT before people is because dogs can be a good guide to what may happen in people," Roberts said. "The dog tumors share many genetic similarities with human tumors, and their tumors appeared spontaneously as they would in humans. Dogs are also treated with many of the same cancer drugs as humans and respond similarly."
The researchers injected the modified bacterial spores into the tumors of 16 dogs and observed the responses. In six dogs, the tumor sizes were reduced; in three dogs, the cancer went away completely.
Human trials are still yet to be done. Zhou said, "We expect that some patients will have a stronger response than others, but that's true of other therapies as well." The team believes the therapy may be effective if combined with other treatments such as chemotherapy or radiotherapy, but only future trials will tell.
Image Credits
C. novyi (Dr. William A. Clark, CDC)
References
Biomed Valley Discoveries. C. novyi-NT.
McCarthy, EF. The Toxins of William B. Coley and the Treatment of Bone and Soft-Tissue Sarcomas. The Iowa Orthopaedic Journal. 26, 154-158. (2006).
Roberts, N. et. al. Intratumoral injection of Clostridium novyi-NT spores induces antitumor responses. Science Translational Medicine. 6, 249ra111. (2014).
