Modern update of once-controversial approach helps a handful of patients
“Live bacteria” and “cancer treatment” may not sound like a promising match, but certain microbes seem able to stall tumor growth when injected into the tumors, according to data presented here on 30 September at the Fourth International Cancer Immunotherapy Conference. The injections appear to activate an immune response that also targets the tumor. There are still questions about the safety of the approach. But given how many patients develop resistance or don’t respond to current cancer treatments, bacterial injections have generated enough interest that they’re part of a new clinical trial combining bacteria with an established immune therapy.
The research carries echoes of a more-than-a-century-old experiment. In the 1890s, oncologist William Coley began to inject cancer patients who had inoperable tumors with a mixture of killed bacteria. Coley reported success with the approach and “Coley’s toxins” were sold as a cancer therapy in the United States even into the 1960s. But other doctors questioned Coley’s results, and the treatment was overtaken by chemotherapy and radiation, which became standard in cancer.
Four years ago, a large team of cancer scientists suggested bacterial injections might be a valid way to treat cancer after all. They published a paper in Science Translational Medicine describing how in six out of 16 dogs with solid tumors, the masses shrank or even disappeared when injected with live copies of the bacterium Clostridium novyi. In that work, the research team first removed a toxin-producing gene from the live bacteria. Encouraged by how the dogs fared, the group also treated a 53-year-old woman with leiomyosarcoma, a form of cancer that begins in smooth muscles. Her tumor shrank as well, though she later sought other treatment for the cancer.
That patient is now the first of many. In additional clinical work led by medical oncologist Filip Janku at the University of Texas MD Anderson Cancer Center in Houston, who was part of the scientific team 4 years earlier, 23 more patients with advanced sarcoma or other solid tumors ranging from breast cancer to melanoma got a single injection into their tumor of anywhere from 10,000 to 3 million Clostridium spores, a dormant form of the bacteria. The research team was surprised and excited by the bacteria’s antitumor effects. Nineteen patients, including that first woman, saw their cancers stabilize, which meant their tumors didn’t continue to grow after treatment. Even though the injections were local, the bacteria also seemed to sometimes stabilize and reduce tumor growth elsewhere in the body as seen on imaging, Janku says.
|Read on: Bacterial injections into tumors show early promise for treating cancer|