In summary, the CAR-mRNA design was stepwise optimized by the incorporation of CleanCap as 5′ cap analog, hAG 5′ UTR and AES/mtRNR1 3′ UTRs as well as m1ψ modification, which achieved a detectable CAR expression on cancer patients’ T cells for at least four days. This evidence concerns the gene MT-RNR1 and cancer.