Scientists in a Seattle lab engineer CAR T-cell cancer therapies.Elaine Thompson / AP

Chemotherapy is the most widely known and widely successful treatment for cancer in medical history, but it’s also infamous for its side effects. For millions of people, surviving cancer means hair loss, months of nausea, drastic weight loss, and extreme fatigue, among many other bodily reactions that can make the treatment process brutal.

While speaking on a panel at Aspen Ideas: Health, co-hosted by the Aspen Institute and The Atlantic, the Carnegie Mellon professor of biological and chemical engineering Elizabeth Wayne pointed out that many current cancer treatments were derived from things originally intended to kill people. “A lot of our drugs are warfare drugs that we’re just hoping people don’t die from afterward,” Wayne explained. “It’s always fascinating to me that one of the first drugs we went to was mustard gas.”

Now scientists are busy exploring better ways forward. “As an oncologist, I just couldn’t accept chemotherapy toxicity,” said Miriam Merad, another panelist and the director of the Precision Immunology Institute at Mount Sinai School of Medicine. “We have an immune system that’s been shaped for millennia to fight against damage, and I thought that we should be able to use it to fight against cancer cells.”

Many researchers and doctors are looking to immunotherapies to wipe out cancers without putting patients through the suffering often associated with surviving the disease. These treatments harness the power of the body’s existing immune defenses, which aren’t very good at attacking cancer cells without medical intervention.

The cancer immunotherapies most widely available now are checkpoint inhibitors such as Keytruda, which take the brakes off the body’s immune responses in order to more effectively unleash them on tumors. Merad said that these drugs have shown particular promise in cancers that are notoriously unresponsive to chemotherapy or radiation. “What was dramatic is that metastatic lung cancer—which doesn’t respond to any therapy—could be cured. The cancer would completely disappear,” she said. “We believe that in the years to come, more than 50 percent of cancer patients are going to receive checkpoint inhibitors.”

The CBS News chief medical correspondent Jonathan LaPook, who moderated the panel, said the most famous recipient of checkpoint inhibitors is probably Jimmy Carter, who was diagnosed with metastatic melanoma in 2015, which had spread to his brain. Normally, survival periods for patients with that type of cancer are less than a year, but Carter is still alive and cancer-free almost four years later.

A second immune system–based cancer treatment, this one in earlier developmental stages, is CAR T-cell therapy. “I think about it as pregaming,” Wayne said. “You’re pregaming your T-cells to be ready to party when they’re back in your body.” T-cells are on the front lines of the body’s immune response, and engineers like Wayne are developing ways to extract them from patients and optimize them to find and fight cancer cells.

“Just like you would give a scent to a bloodhound and say ‘Go get it,’ you’re giving the scent of the cancer to these T-cells and then multiplying them a billionfold and putting them back in,” LaPook explained.

The downside of this treatment is that it’s expensive and time-consuming. T-cells have to be harvested, adjusted, and proliferated from individual patients, which takes four to six weeks. That’s more time than some people have, and T-cells from previous patients can’t be used to treat future tumors in others, although Wayne said that she and other researchers are working on that technology.

Despite the current cost, Merad said there’s still immense cause for optimism for the future of immunotherapies in cancer treatment. “This is just the beginning,” she said. “There are two molecules on the market, but there are hundreds of them we can exploit.”

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