Extracellular vesicles powered cancer immunotherapy: Targeted delivery of adenovirus-based cancer vaccine in humanized melanoma model

Malignant melanoma, a rapidly spreading form of skin cancer, is becoming more prevalent worldwide. While surgery is successful in treating early-stage melanoma, patients with advanced disease have only a 20 % chance of surviving beyond five years. Melanomas with mutations in the NRAS gene are characterized for a more aggressive tumor biology, poorer prognosis and shorter survival. Hence, new therapeutic strategies are needed, especially for this specific group of patients. Novel approaches, such as cancer vaccines, offer promising solutions by stimulating the anti-tumor immune response. Nevertheless, their clinical efficacy is still modest and more effective approaches are required. Herein, we propose the systemic administration of the adenovirus-based cancer vaccine complexed in extracellular vesicles (EVs) with the aim of achieving a targeted therapeutic effect. The vaccine was based on previously tested oncolytic adenovirus Ad5/3-D24-ICOSL-CD40L in combination with melanoma-specific antigens targeting NRAS mutations to enhance the anticancer effect. The antineoplastic properties of the oncolytic vaccine were evaluated in xenograft MUG Mel-2 melanoma BALB/c nude mice. Moreover, to mimic the tumor microenvironment, while investigating at the same time immune cell infiltration and drug penetration, we established a 3D co-culture model based on human NRAS mutated MUG Mel-2 spheroids and PBMCs (HLA matched), which displayed a synergistic effect when treated with the cancer vaccine compared to relative controls. Subsequently, we investigated the systemic delivery of the vaccine in EV formulations in a humanized NSG MUG Mel-2 melanoma mouse model. Our study provides a promising strategy for a tumor-targeted vaccine delivery by EVs, resulting in improved anticancer efficacy and increased infiltration of tumor-infiltrating lymphocytes. This study explores the potential of EVs for the selective delivery of cancer vaccines against malignancies, such as NRAS melanoma. Overall, this research could pave the way for applying autologous EVs as a safe and efficacious tool for targeted cancer therapy.