A cancer drug just passed its Phase 3 trial, and the active ingredient comes from Cold War nuclear bomb material the US government was paying to destroy. The drug is actinium-225 attached to a peptide that hunts down a receptor on neuroendocrine tumor cells. Once it docks, the actinium fires off alpha particles that travel only 2 to 3 cell widths before stopping. The tumor cell dies. The healthy cell next door barely notices. The science was the easy part. Actinium-225 is one of the rarest…