When Karen Koehler was diagnosed with chronic lymphocytic leukemia in 2011, she was told not to worry. She had a mild case that could simply be monitored, her doctor said. But two years later, the cancer took a turn for the worse when a genetic mutation made it aggressive and difficult to treat with chemotherapy. “I was told I had 10 months to live,” said Koehler, 59, a retired teacher who lives in Park Ridge, New Jersey. At best, she was told, chemo might stretch that to two years.
Then Koehler was accepted into a clinical trial at Memorial Sloan Kettering Cancer Center in New York that aimed to turn her own immune cells into cancer killers. Within a month of treatment, her leukemia had vanished. “There were no cancer cells whatsoever,” said Koehler, who remains cancer-free today.
The Memorial Sloan Kettering oncologists, whose research helped Koehler, are now working on the latest breakthrough in immunotherapy – CAR T or ‘chimeric antigen receptor T cell’, a personalised one-time infusion of immune cells that will destroy cancer cells and remain in the body to prevent it from ever coming back.
The process involves collecting a sample of blood from a patient, extracting the T-cells (immune cells) from the blood, engineering them to recognize and attack the patient’s own particular cancer, expanding the population of the cells in a lab, then infusing them back into the body. Currently, CART is being used in trials for blood cancers such as leukaemia and lymphoma but scientists are hoping to test it in ovarian, pancreatic, lung and brain cancer patients too.
Unlike chemotherapy and radiotherapy, the side effects of immunotherapy are much milder, reported the US News. The only potentially serious side effect is what’s called “cytokine release syndrome,” an uncontrolled activation of the immune system that can cause high fevers, dangerously low blood pressure and strain on the Kidneys, with some patients needing to be admitted to intensive care as a result.
“We’re working on trying to prevent” side effects, says Dr. William Wierda, a professor in the department of leukemia at Houston’s MD Anderson Cancer Center, which is participating in several CAR T clinical trials. “In some cases, we can identify patients who are at higher risk of cytokine release syndrome. And now we’re discussing whether tocilizumab could be used to prevent it.”
The process of using CAR Ts to treat cancer will not only extend to many more tumor types, it will also become more streamlined and easier for patients, predicts Sloan Kettering’s Park. He believes the T-cell collection process will eventually “be like getting a blood draw from your doctor’s office.” The engineering time will be shortened and perhaps even automated, he says. “It only gets better from here.”
What is immunotherapy?
Immunotherapy is a treatment aimed at boosting the body’s immune system to help it destroy cancer cells. In order for the immune system to become activated, it needs to recognise the presence of a foreign invader. But the problem with cancer is that it is made up of our own cells and not a foreign organism. Therefore, the cancer cells go undetected by the immune system as it fails to recognise the threat they pose. This means they can grow unchecked no matter how much damage they cause.
Immunotherapy drugs help the immune system recognise cancer cells and therefore allows the immune system to kick in and kill off the cancer. By harnessing the body’s immune system, drugs such as Keytruda and Yervoy have helped turn what used to be an incurable disease such as advanced melanoma and lung cancer into a condition people can live with for many many years.
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