In situ delivery of nanoparticles formulated with micron-sized crystals protects from murine melanoma

J Immunother Cancer. 2022 Sep;10(9):e004643. doi: 10.1136/jitc-2022-004643.


Introduction: Intratumoral injections of novel therapeutics can activate tumor antigen-specific T cells for locoregional tumor control and may even induce durable systemic protection (against distant metastases) via recirculating T cells. Here we explored the possibility of a universal immunotherapy that promotes T-cell responses in situ and beyond, upon intratumoral injection of nanoparticles formulated with micron-sized crystals.

Methods: Cucumber mosaic virus-like particles containing a tetanus toxin peptide (CuMVTT) were formulated with microcrystalline tyrosine (MCT) adjuvant and injected directly in B16F10 melanoma tumors. To further enhance immunogenicity, we loaded the nanoparticles with a TLR7/8 ligand and incorporated a universal tetanus toxin T-helper cell peptide. We assessed therapeutic efficacy and induction of local and systemic immune responses, including RNA sequencing, providing broad insight into the tumor microenvironment and correlates of protection.

Results: MCT crystals were successfully decorated with CuMVTT nanoparticles. This 'immune-enhancer' formed immunogenic depots in injected tumors, enhanced polyfunctional CD8+ and CD4+ T cells, and inhibited B16F10 tumor growth locally and systemically. Local inflammation and immune responses were associated with upregulation of genes involved in complement activation and collagen formation.

Conclusions: Our new immune-enhancer turned immunologically cold tumors into hot ones and inhibited local and distant tumor growth. This type of immunotherapy does not require the identification of (patient-individual) relevant tumor antigens. It is well tolerated, non-infectious, and affordable, and can readily be upscaled for future clinical testing and broad application in melanoma and likely other solid tumors.

Keywords: Immunotherapy; Melanoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Neoplasm
  • Humans
  • Immunotherapy
  • Melanoma* / drug therapy
  • Mice
  • Nanoparticles*
  • Tetanus Toxin
  • Tumor Microenvironment


  • Antigens, Neoplasm
  • Tetanus Toxin