While cancer immunotherapy provides new exciting treatment options for patients, there is an urgent need for new strategies that can synergize with immune checkpoint blockers and boost the patient response rates. We have developed a personalized vaccine nanodisc platform based on synthetic high-density lipoproteins for co-delivery of immunostimulatory agents and tumor antigens, including tumor-specific neoantigens. Here we examined the route of delivery, safety profiles, and therapeutic efficacy of nanodisc vaccination against established tumors. We report that nanodiscs administered via the subcutaneous (SC) or intramuscular (IM) routes were well tolerated in mice without any signs of toxicity. The SC route significantly enhanced nanoparticle delivery to draining lymph nodes, improved nanodisc uptake by antigen-presenting cells, and generated 7-fold higher frequency of neoantigen-specific T cells, compared with the IM route. Importantly, when mice bearing advanced B16F10 melanoma tumors were treated with nanodiscs plus anti-PD-1 and anti-CTLA-4 IgG therapy, the combination immunotherapy exerted potent antitumor efficacy, leading to eradication of established tumors in ∼60% of animals. These results demonstrate nanodiscs customized with patient-specific tumor neoepitopes as a safe and powerful vaccine platform for immunotherapy against advanced cancer.