Magnetic sculpture-like tumor cell vaccines enable targeted <i>in situ</i> immune activation and potent antitumor effects

<b>Rationale:</b> Tumor cells are ideal candidates for developing cancer vaccines due to their antigenic profiles, yet existing whole-cell vaccines lack efficacy. This study aimed to develop a novel whole-cell vaccine platform that combines immunogenicity, structural integrity, and tumor-targeting capabilities. <b>Methods:</b> We created "Magnetic Sculpture-like (MASK) Cells" by treating tumor cells with high-concentration FeCl₃, inducing rapid morphological fixation without traditional chemical crosslinking. MASK cells were characterized for proliferative capacity, biomolecule retention, and magnetic properties. Vaccine efficacy was tested <i>in vitro</i>, in melanoma-bearing mouse models, and through spatial transcriptomic profiling of tumor microenvironments. Combination therapy with anti-PD-1 was further evaluated. <b>Results:</b> MASK cells lose proliferative ability but retain biomolecules and architecture. MASK cells promote dendritic cell maturation and T cell responses against tumors. Vaccines combining MASK cells and adjuvant potently suppress melanoma growth. Uniquely, FeCl₃ sculpting imparts magnetism to cells, enabling directional navigation to tumors using magnetic fields and enhanced <i>in situ</i> immune activation. Spatial transcriptomics reveals DC and T cell activation and tumor cytotoxicity after MASK vaccination. Combined with anti-PD-1, MASK cell vaccines strongly inhibit growth and improve survival. <b>Conclusion:</b> MASK cells represent a promising new approach for targeted, patient-specific anti-tumor therapeutics.