In a ray of hope for treating cancers, US-based scientists have successfully shrunk cancer tumors in pet dogs, rats and one human patient by simply injecting common soil bacteria.
The researchers directly injected the tumors with a modified version of Clostridium novyi (C. novyi-NT) to witness strong and precisely targeted anti-cancer responses.
The preliminary findings are being seen as a major breakthrough in the cancer treatments. The researchers feel the experimental treatment may have the potential to turn more effective than the existing cancer therapies for some inoperable cancerous tumors in breast, lung and pancreas. Cancerous tumors in these organs often fail to respond to radiation and chemotherapy.
The study was conducted by the team of researchers from Johns Hopkins Kimmel Cancer Center in Baltimore, MD.
The two existing form of cancer treatment includes- radiation and chemotherapy. Radiation needs oxygen to kill cancerous cells but the deep interior of tumors is nearly oxygen-free. On the other hand, chemotherapy uses blood vessels to take drugs to the tumors.
“But these conditions make the tumors perfect for bacteria that thrive in low-oxygen environments,” said Shibin Zhou, senior study author and an oncologist from Johns Hopkins Sidney Kimmel Comprehensive Cancer Center in Baltimore, Maryland.
In a similar experiment 100 years ago, the doctors first used streptococcus bacteria to attack tumors. But that turned futile as the century old experiment along with the recent attempts with salmonella proved to be toxic and ineffective.
A decade ago, scientists from Hopkins resurrected the approach using Clostridium novyi soil bacteria, which was genetically modified by removal of DNA that creates a toxic protein. The researchers decided to inject only spores, as they are less likely to cause infection.
Veterinary oncologists were then enlisted by the researchers at seven pet clinics in the US. Around 16 dogs, ranging from a border collie to shepherds, were directly injected with 100 million clostridium spores. They found that the tumors shrank in three of the 16 dogs. Also the tumors were found disappeared in three more.
Then a patient with retroperitoneal leiomyosarcoma at M.D. Anderson Cancer Center in Houston received an injection of 10,000 spores into a metastatic tumor in her arm.
Retroperitoneal leiomyosarcoma is cancer of the abdomen that had spread to liver, lungs, arms and bones in the patient.
Following injection, the patient ran a fever and felt severe pain. Doctors say this is a sign that immune system is attacking the cancer. But the tumor shrank her arm bone and elsewhere they continued to grow.
Researchers concluded that the enzymes released by the spores destroyed nearby tumor cells.
The research has been published in the journal Science Translational Medicine.