12 established A20 tumors were injected with either fluorophore (BDK) or non-fluorophore mRNA-CART. Phenotypic surface marker expression and BDK was used to identify transfected cells (A) Top: Established A20 tumors were injected with non-fluorophore mRNA-CART. Gates indicate background staining. Bottom: Established A20 tumors were injected with (BDK) mRNA-CART. Gates indicates percentage of parent population transfected with mRNA-CARTs. Bar graph: average percent transfected cells in the injected tumor. (B) Expression of immunomodulatory mRNA in HeLa cells 12 hrs after treatment with mRNA-CARTs. (C) Tumor growth and survival of Ctr., CD70, OX40L, CD80/86, IL-12, and IFNγ mRNA-CART treated animals. Mice with tumors >15mm in the largest diameter were euthanized. Survival of OX40L, and CD80 and CD86 mRNA-CART treated mice were compared to control mRNA-CART treated. Survival significance was calculated using Log Rank (Mantel-Cox) test. Ns, not significant; *, P < 0.05; **, P < 0.01; ***, P < 0.001 ****, P < 0.0001. Data representative of 2–4 independent experiments.