An unconventional T cell, the mucosal-associated invariant T (MAIT) cell, may enable pan-cancer immunotherapies. Unlike conventional T cells, which recognize cancer cells via the human leukocyte antigen system, MAIT cells possess a T-cell receptor (TCR) that works through the evolutionarily conserved monomorphic MHC class I-related protein, or MR1. T cells equipped with the new TCR were shown, in the lab, to kill lung, skin, blood, colon, breast, bone, prostate, ovarian, kidney, and cervical cancer cells, while ignoring healthy cells.