The purpose of this studywas to evaluate the efficacy of poly(lactic- co-glycolic acid) (PLGA)-based vaccines in breaking immunotolerance to cancer-associated self-antigens. Vaccination of mice bearing melanoma B16 tumors with PLGA nanoparticles (NP) co-encapsulating the poorly immunogenic melanoma antigen, tyrosinase-related protein 2 (TRP2), along with Toll-like receptor (TLR) ligand (7-acyl lipid A) was examined. Remarkably, this vaccine was able to induce therapeutic anti-tumor effect. Activated TRP2-specific CD8 T cells were capable of interferon (IFN)-γ mice. More importantly, TRP2/7-acyl lipid A-NP treated group has shown immunostimulatory mileu at the tumor microenvironment, as evidenced by increased level of pro-inflammatory cytokines compared to control group. These results support the potential use of PLGA nanoparticles as competent carriers for future cancer vaccine formulations.