A number of cancers, including certain brain and liver tumors, as well as myeloid leukemias, are driven by mutations in the enzyme isocitrate dehydrogenase 1, or IDH1. Drugs that block mutated IDH1 (mIDH1) have recently come onto the market and effectively slow tumor growth, but the exact mechanism at work to stall tumors is still unclear.
Reporting in Science, researchers at Massachusetts General Hospital and the Broad Institute of MIT and Harvard have made a surprising discovery about these drugs. They found that mIDH1 inhibitors trick the tumor cells into thinking they are infected with a virus, causing the immune system to mount an antiviral response. This mechanism, known as “viral mimicry,” relies on the relics of ancient viral infections that remain scattered throughout the genome but are usually unexpressed. Treatment with mIDH1 blockers unearths these remnants, triggering an immune response against the tumor cells.
