Synergistic anti-tumor effects of mRNA vaccine and PERK inhibitor combination in melanoma treatment.

Melanoma is a highly aggressive form of skin cancer. mRNA vaccines deliver genetic material encoding specific antigens into cells, thereby triggering the host immune system to produce the antigen. Gp-100, an antigenic protein expressed on the surface of melanoma cells, serves as a target mRNA to stimulate the cytotoxic T lymphocyte (CTL) response. However, the absence of natural killer (NK) cells can lead to significant tumor cell proliferation. Gardiquimod, a TLR7 agonist, enhances NK cell cytotoxicity, promoting tumor clearance. In advanced melanoma, the unfolded protein response (UPR) often becomes dysregulated. By inhibiting protein kinase R-like ER kinase (PERK), the UPR can be disrupted, inducing apoptosis in cancer cells and shifting the tumor microenvironment (TME) towards an increased M1/M2 macrophage ratio. This study developed a cationic liposome-based mRNA vaccine (GD-LPR) using DOTMA to co-deliver gp-100 mRNA and the TLR7 agonist Gardiquimod, combined with the PERK inhibitor GSK2656157 (GSK), for synergistic melanoma immunotherapy. GD-LPR achieved 95 % mRNA encapsulation efficiency and demonstrated enhanced dendritic cell maturation and NK cell activation both in vitro and in vivo. In subcutaneous melanoma models, GD-LPR+GSK reduced tumor volume and prolonged survival by modulating the tumor microenvironment (TME): increasing CD8+ T cells (Fig. 3 f), repolarizing M2 to M1 macrophages (Fig. 4 f), and suppressing IL-10 while elevating pro-inflammatory cytokines (IL-2, IFN-γ, TNF-α). Mechanistically, GSK inhibited PERK/ATF-4 signaling, synergizing with GD-LPR to suppress lung metastasis. The combination of the GD-LPR vaccine and GSK provides new potential strategies for treating melanoma, particularly in subcutaneous tumors and lung metastases.