ELI5: Moderna made a cancer vaccine that is custom for every person. Doctors read the DNA of your tumor, find what makes it unique, then make an mRNA shot that teaches your immune system, “Attack cells that look like this.” They combine it with Keytruda, a drug that helps stop cancer from hiding from your immune system. It just succeeded in a Phase 3 melanoma trial. Not a cure for all cancer. But a pretty huge idea if it works for other cancers too.