Immunotherapy as a means for cancer treatment has been investigated for over a century. While studies have been completed using different immunological strategies, development of a clinical therapeutic cancer vaccine has proven elusive. Recently, success has been seen with prophylactic vaccines for cancers with known viral origins (Gardasil® and Cervarix for Human Papiloma Virus). However, such strategies do not address the challenge in generating effective immune response against other tumor antigens, most of which are weakly immunogenic self-antigens. Tolerance to these self-antigens could ultimately limit the patient's ability to mount an effective anti-tumor immune response. The US Food and Drug Administration recently approved the first DC cell-based cancer vaccine, Provenge®, for use in prostate cancer. This vaccine requires cell isolations from the patient as well as in vitro DC modifications, which ultimately leads to high cost as well as multiple procedures. However, results indicate that, on average, patients live only four months longer than those receiving a placebo. While this work remains important, and offers proof that priming DCs can improve the lifespan of a patient, it ultimately does not offer a long-term cure. Direct and highly efficient in vivo delivery of antigens to DCs could overcome the challenges associated with ex vivo DC manipulation and may offer a more scalable method for generating anti-tumor immunity. This research focuses on the development of novel formulations that allow simultaneous delivery of protein/peptide-based tumor antigens and immune-modulatory nucleic acids (siRNA and immune stimulatory CpG) to the same dendritic cells (DCs) in-vivo. Such formulations allow a synthetic immune-priming center to be created at the site of immunization and simultaneously deliver the tumor antigen to DCs and modulate their immune response through IL-10 silencing. Our hypothesis is that using such a DC-targeted dual delivery system we will be able to illicit strong T helper 1 (TH1) and Cytotxic T Lymphocyte (CTL) response in vivo against a wide array of tumor antigens. This can become a platform technology where the biomolecules (antigen and immunomodulatory agents) can be easily varied based on particular cancers.