A single-dose intratumoral administration of such CDN-loaded polymersomes in a mouse melanoma model remodeled the tumor immune milieu, as characterized by increased populations of tumor-infiltrating neutrophils as well as CD8+ and CD4+ T cells, activated DCs indicated by CD86 expression, which altogether reprogram the tumor microenvironment to be 'hot' or T cell-inflamed for efficacious immunotherapy. The gene discussed is CD8A; the disease is neoplasm.