mRNA: delivering an antitumor message?

Evaluation of: Fotin-Mleczek M, Duchardt KM, Lorenz C et al.: Messenger RNA-based vaccines with dual activity induce balanced TLR7-dependent adaptive immune responses and provide antitumor activity. J. Immunother. 34(1), 1-15 (2011). Two decades ago, mRNA was proposed as an active pharmaceutical ingredient for the therapy of cancer. Although direct delivery of mRNA to mice was shown to be feasible, mRNA has been mainly used for ex vivo modification of antigen-presenting cells, such as dendritic cells. Fotin-Mleczek et al. introduces a two-component mRNA vaccine, consisting of antigen mRNA (firefly luciferase, ovalbumin or prostate carcinoma-specific antigen) and mRNA that is formulated in protamine as a source of not only antigen but also Toll-like receptor 7 ligands. Direct administration of the mRNA vaccine in mice results in sustained humoral and cellular immune responses, comprising, among others, antigen-specific cytotoxic T cells that mediate strong antitumor responses, in both prophylactic and therapeutic settings. In conclusion, this study highlights the potential of mRNA vaccines to induce immune responses and mediate sustained antitumor activity.