Messenger RNA Vaccines: Beckoning of a New Era in Cancer Immunotherapy

Messenger RNA (mRNA) vaccines are a relatively new class of vaccines. They combine the potential of mRNA to encode for almost any protein with an excellent safety profile and a flexible production process. During the last decade, the mRNA vaccine approach has been increasingly recognized and viewed as a versatile tool for the development of new innovative therapeutics not only in infectious disease settings but also in cancer. mRNA vaccines traditionally consist of a messenger RNA synthesized by in vitro transcription using a bacteriophage RNA polymerase and a template DNA that encodes the antigen(s) of interest. Once administered and internalized by host cells, the mRNA transcripts are translated directly in the cytoplasm of the cell. The resulting antigens are presented to the immune system cells to stimulate an immune response. Dendritic cells (DCs) can be utilized as a carrier by delivering tumor-associated antigen mRNAs or total tumor RNA to their cytoplasm; then, the mRNA-loaded DCs can be delivered to the host to elicit a specific immune response. Recently, 2 mRNA vaccines were approved for the first time for human use-to prevent COVID-19 infection-bringing excitement for the future possibilities of this approach for cancer immunotherapy as well as for preventing other infectious diseases.