In a small new study published in Science Translational Medicine, researchers who are pioneering an immune-based treatment for cancer report encouraging results among people with otherwise untreatable non-Hodgkin lymphoma, a blood cancer.
Led by Dr. Cameron Turtle from the Fred Hutchinson Cancer Research Center, the scientists gave a group of 32 people different chemotherapy regimens and then introduced immune cells specifically designed to target and destroy cancer cells. All of the patients had been given at least one traditional treatment, including some who had had stem cell transplants, but none had good responses to these approaches. After the immunotherapy, however, seven people in one treatment group went into complete remission, while another four saw their disease progress more slowly.
The treatment, called CAR-T cell therapy, is targeted toward blood cancers, where doctors can eliminate cancer cells and replace them with healthy blood and immune cells. The strategy hinges on two important steps. First, doctors need to remove as much of a patient’s cancer-ridden blood cells as possible — they do that with chemotherapy — in order to make room for a new population of healthy blood and immune cells. If too many of the cancer cells remain, then they could outcompete the new cells and simply destroy them. To ensure that doesn’t happen, Turtle and his team tested a two-drug chemotherapy regimen and compared it to a single drug chemo strategy. Those getting the combination showed the best results, amounting to a 64% complete remission rate; by comparison, only one of the people getting the single chemotherapy agent went into complete remission (an 8% rate).
Next, the researchers need to re-introduce the right amount of the right immune cells that can fight cancer. Known as T cells, these contain specific receptors that allow some of them to recognize and bind to cancer cells and others to destroy them. To enhance the potency of the therapy, the scientists coaxed these cells to grow in the lab and genetically engineered them to express the tumor-specific receptor. The idea is to then reintroduce these cells back into patients and give them new, healthy blood cells that are cancer-free.