Engineering monocyte-derived dendritic cells to secrete interferon-α enhances their ability to promote adaptive and innate anti-tumor immune effector functions

Dendritic cell (DC) vaccination has demonstrated potential in clinical trials as a new effective cancer treatment, but objective and durable clinical responses are confined to a minority of patients. Interferon (IFN)-alpha, a type-I IFN, can bolster anti-tumor immunity by restoring or increasing the function of DCs, T cells and natural killer (NK) cells. Moreover, type-I IFN signaling on DCs was found to be essential in mice for tumor rejection by the innate and adaptive immune system. Targeted delivery of IFN-alpha by DCs to immune cells could boost the generation of anti-tumor immunity, while avoiding the side effects frequently associated with systemic administration. Naturally circulating plasmacytoid DCs, major producers of type-I IFN, were already shown capable of inducing tumor antigen-specific T cell responses in cancer patients without severe toxicity, but their limited number complicates their use in cancer vaccination. In the present work, we hypothesized that engineering easily generated human monocyte-derived mature DCs to secrete IFN-alpha using mRNA electroporation enhances their ability to promote adaptive and innate anti-tumor immunity. Our results show that IFN-alpha mRNA electroporation of DCs significantly increases the stimulation of tumor antigen-specific cytotoxic T cell as well as anti-tumor NK cell effector functions in vitro through high levels of IFN-alpha secretion. Altogether, our findings mark IFN-alpha mRNA-electroporated DCs as potent inducers of both adaptive and innate anti-tumor immunity and pave the way for clinical trial evaluation in cancer patients.