Magazine article Newsweek

Programming Bacteria to Kill Cancer Cells; New Immunotherapy Research Holds Promises of Treating Cancer and Providing Long-Term Protection from Recurrence

Magazine article Newsweek

Programming Bacteria to Kill Cancer Cells; New Immunotherapy Research Holds Promises of Treating Cancer and Providing Long-Term Protection from Recurrence

Article excerpt

Byline: Lecia Bushak

In the late 1800s, Dr. William Coley--a bone surgeon and cancer researcher at New York Cancer Hospital--observed something peculiar. A patient named Fred Stein was suffering from a tumor growing in his cheek--until he became infected by Streptococcus pyogenes bacteria (which causes strep throat). Shortly after his infection, the cancer began disappearing, as though the fever had burned it away.

Afterward, Coley began to notice that several other cancer patients who had recently undergone tumor-removal surgery were more likely to recover from their cancer if they developed a post-surgical infection. In an effort to figure out why, Coley began injecting inoperable cancer patients with streptococcal bacteria. These came to be known as "Coley toxins." In one case, Coley treated a 21-year-old man with a mix of bacteria and bacterial lysates--natural secretions of bacteria that keep the immune system on alert--who then had a complete remission.

Coley injected over 1,000 patients with his toxins--and many recovered. But he never properly documented all his cases or followed up with enough patients, and after his death in 1936, general medical opinion dismissed his methods in favor of radiation and chemotherapy. It wasn't until much later, when several pioneering cancer researchers revisited his work, that the medical community began to realize that Coley--sometimes called the "father of immunotherapy"--had been onto something.

In the fall of 2014, the FDA approved an immunotherapy drug known as Anti-PD1 for melanoma, the most serious type of skin cancer. Soon after, Anti-PD1 became the standard of care for melanoma. It's so effective, in fact, that it's used completely alone, without the need for chemotherapy or radiation. "I have not given chemotherapy to a person with melanoma for the past two years," says Dr. Antoni Ribas, a medical oncologist at UCLA who treats mainly melanoma patients. "The days of chemotherapy for these diseases are over."

Anti-PD1, like all immunotherapies, works by hacking your immune system--essentially, teaching it how to attack cancer cells, which it would otherwise ignore. There are huge advantages to immunotherapy compared with traditional cancer treatments. When patients undergo chemotherapy, the side effects are often debilitating, including extreme pain and fatigue, nausea, diarrhea, hair loss, poor appetite and a risk for life-threatening infections, as well as long-term health consequences like heart and lung disease. In addition, chemotherapy and radiation generally don't guarantee lasting protection from recurrence.

Immunotherapy, on the other hand, "would get the immune system to impact cancer long-term, because the immune system has the ability to remember," says Ribas. "So if you develop a therapy that turns on the immune system correctly, it will continue to remember that the bad guy is the tumor and should be attacked."

That's why the field of immunotherapy research has exploded in recent years. And one of the most promising areas of cancer immunotherapy goes all the way back to Coley: Controlled bacteria might be the best tool yet to turn the immune system into a cancer-fighting machine.

We know Salmonella bacteria as a sickening bug, lurking in undercooked meat or buckets of cookie dough and making its way into our system if we don't prepare our food properly. When it does, it wreaks havoc on us in the form of nausea, fever, diarrhea, vomiting and chills. But there's another side of Salmonella.

Roy Curtiss, a professor who runs a lab at the Arizona State University's Biodesign Institute has been studying the bacteria's cancer-killing properties for some time now. He's found that certain strains of Salmonella, when genetically modified to become safer, have the ability to enter cancer cells and take over. It's different from anti-PD1 therapy, where the immune system is taught to recognize cancer cells that were previously "hidden"--with Salmonella, the bacteria itself can exert its toxic effects on individual tumor cells. …

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