Hotz et al. investigated the intra-tumoral delivery of saline-formulated mRNA encoding a four-component injection mixture of cytokine mRNAs (the components being active IL-15 (a fusion protein of IL-15 and the sushi domain of IL-15Ra), single-chain IL-12 (a fusion protein of p35 and p40) a granulocyte–macrophage colony-stimulating factor (GM-CSF), and interferon-alpha 2b) and showed strong anti-tumor activity [28]. Here, IL15 is linked to neoplasm.