Bacteria deliver radioactive drugs to treat pancreatic cancer

To combat pancreatic cancer, notoriously resistant to many treatments, researchers at the Albert Einstein College of Medicine in New York's Yeshiva University have turned to living bacteria that can deliver radioactivity directly to tumor cells.

In animal trials, the scientists used the immune-system-attacking microorganism listeria monocytogenes to burrow into white blood cells and tweak their DNA in such a way that prompts them to recognize and destroy cancer cells. But the bacteria did more than that: The single-celled microbes also infected cancer cells and killed them without harming the surrounding healthy tissue, according to a 2009 study in the journal Cancer Research.

So in the ensuing years, Claudia Gravekamp and her team loaded the listeria with radioactive rhenium, which when injected together into mice with a metastatic form of pancreatic cancer reduced the number of cancer cells by 90%. Gravekamp hopes to boost that success rate to 100%, as she published in the newest study this week in the Proceedings of the National Academy of Sciences.

By delivering the radioactive material with listeria, the researchers found that healthy cells remain largely unaffected. The bacteria shut down the immune system in the vicinity of the tumor, leaving the offending cells unguarded.

"By turning off the immune cells that would have protected them, the cancer cells make themselves uniquely vulnerable to the treatment," Gravekamp told Wired's ScienceNOW. "We envision this approach as a second-line therapy, which would follow either surgery or radiation to remove the primary tumor."

The treatment must still be proven as a safe and viable option before making its way into the clinic, fellow researchers say, but because of the grisly nature of pancreatic cancer in particular, the discovery could lead to more creative delivery options for cancer drugs.

- here's the ScienceNOW story
- here's the recent paper
- and 2009's Cancer Research paper
- and FierceBiotechResearch's take

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