How Close Is The Cure?
If it seems like the war against cancer has dragged on for an obscenely long time, that’s because cancer is a formidable adversary. Still, there’s so much hope. Already there are targeted therapies on the market that inhibit proteins on or in cancer cells that cause the cells to grow. Compared with chemotherapy, which is like killing a mosquito with a brick, these treatments are much more specific. A drug called Gleevec, for example, blocks a mutant gene that causes leukaemia cells to form and spiral out of control. Herceptin, meanwhile, blocks a protein that tends to grow or divide faster in the cancer cells of women with HER2positive breast cancer. There are even much stronger chemotherapies for HER2-positive breast cancer and Hodgkin’s lymphoma that use similar protein targeting. Most doctors agree that the next frontier in cancer research, though, is immunotherapy – getting the immune system to find and kill cancer on its own, the same way it would tackle the flu. ‘It happens to be what I study, but I would bet everywhere you go you will hear that immunotherapy is the next big thing and it will dominate the landscape for the next decade,’ says Dr Crystal Mackall, a paediatric oncologist at Stanford University in the US. Cancer hides from the immune system by pretending it’s a normal part of the body: unlike a splinter or a virus, cancer cells contain ‘self’ proteins rather than foreign antigens, making it more challenging for white blood cells to attack. In checkpoint inhibitor therapy, doctors remove a brake from the immune system that would normally prevent its killer cells (called T-cells) from going after cancer. Keytruda – approved for melanoma, non-small cell lung cancer and several other cancers – is one checkpoint inhibitor drug that has helped some ostensibly terminal patients live for years. Up next is the first CAR T-cell therapy, in which doctors remove T-cells from a patient’s body, insert a mechanism targeting cancer (much like the ones that make your immune cells recognise chickenpox or measles) and then reinfuse them. In August last year, the Food and Drug Administration in the US approved the first CAR T-cell therapy, called Kymriah, to fight leukaemia in children and adults. – Jacqueline Detwiler