Current research progress in the field of cancer immunotherapy has positioned MAIT cells as highly promising “off‐the‐shelf” immunotherapeutic carriers owing to their unique biological characteristics—including the expression of an invariant TCR α chain restricted by the highly conserved MHC class I‐like molecule MR1, the ability to recognize microbe‐derived riboflavin metabolic derivatives, and strong cytotoxicity as well as the capacity to home to mucosal barrier tissues [1, 2, 307, 308]. This evidence concerns the gene MR1 and cancer.