Adoptive cell therapy for cancer involves harvesting T cells from a patient and expanding and sometimes modifying them in the laboratory before reinfusion. It has been challenging to create T cells that are both potent and durable. In a new study, researchers report the potent anti-tumor properties of hybrid Th1/Th17 cells that combine the cancer-fighting properties of Th1 cells and the ability of Th17 cells to self-renew and regenerate.