While bacteria can cause nasty infections, a weakened version of them also kill cancer cells, suggests first-in-man research being presented at the seventh annual Symposium on Clinical Interventional Oncology (CIO), in collaboration with the International Symposium on Endovascular Therapy (ISET).
Researchers injected a weakened strain of Clostridium novyi (or C. novyi-NT) bacteria spores into tumors. Imaging evidence demonstrated that the bacteria grew in the tumors and killed cancer cells. “When tumors reach a certain size, parts of them do not receive oxygen, which makes them resistant to conventional therapies such as radiation and chemotherapy,” said researcher Ravi Murthy, M.D. professor of interventional radiology at MD Anderson Cancer Center, Houston. “C. novyi-NT thrives under these conditions, hones in on the low-oxygen areas and destroys tumors from the inside while sparing normal tissue.”
A close relative of the bacteria that causes botulism, C. novyi lives in soil. Researchers have removed the lethal toxin so the bacteria are weakened. In the study, they injected the resulting C. novyi-NT spores through the skin under radiographic guidance into tumors in six people. Growth of C. novyi was confirmed when computed tomography (CT) and magnetic resonance imaging (MRI) scans of the treated tumors showed gas pockets and evidence of necrosis, or cell death. Fever and elevated white blood cell count provided further evidence that the bacteria were growing and destroying cancer cells.
Once inside the tumor, the C. novyi-NT spores germinate, kill tumor cells and then feast on the waste. C. novyi-NT bacteria stop growing and die when exposed to oxygen which is abundant in healthy tissue. C. novyi-NT also is known to provoke an immune response against the cancer. “Essentially, C. novyi-NT causes a potent cancer killing infection in the tumor,” said principal investigator Filip Janku, M.D., associate professor in the Department of Investigation Therapeutics, MD Anderson Cancer Center, Houston.
Six patients have been treated to date. Five are alive and one died from unrelated causes after seven months.