Radioactive bacteria have been developed as a potent new treatment for one of the most deadly cancers.
In laboratory tests, the modified microbes virtually halted the spread of pancreatic cancer in mice without harming healthy tissue.
The bacteria, a weakened form of the Listeria bug that causes food poisoning, act like missiles tipped with atomic warheads. When they infect cancer cells, they destroy them with blasts of radiation. But the radioactive emissions are short-lived, so damage is largely confined to the target area.
Scientists studied the treatment using mice with a highly aggressive form of pancreatic cancer. They found the bacteria dramatically reduced the cancer's spread, or metastasis.
"We're encouraged that we've been able to achieve a 90% reduction in metastases in our first round of experiments," said study co-author Dr Claudia Gravekamp, from the Albert Einstein College of Medicine in New York City. "With further improvements, our approach has the potential to start a new era in the treatment of metastatic pancreatic cancer."
Each year around 8,400 people in the UK are diagnosed with pancreatic cancer. The disease is one of the deadliest cancers, with just 3.6% of patients surviving five years or more. Just under 8,000 pancreatic cancer deaths occur each year in the UK.
The new research, reported in the journal Proceedings of the National Academy of Sciences, builds on previous work suggesting that Listeria might have cancer-fighting potential.
Several years ago scientists discovered that a weakened form of Listeria monocytogenes bacteria can infect cancer cells while leaving normal cells unharmed. Later researchers showed Listeria could be harnessed to carry an anti-cancer drug into tumour cells in laboratory cultures, but this approach was never tested in animals.
The new study takes the technique further by using Listeria to target cancer with radiation. The treatment could be improved by fine-tuning the therapy, using higher doses of radiation, or adding additional anti-cancer agents to the bacteria, say the researchers.
The Einstein College of Medicine has filed a patent application for the technology used in the treatment and is looking for partners to develop it further.