Redirecting Killer T Cells through Incorporation of Azido Sugars for Tethering Ligands

Antibody-targeted T cells and natural killer cells for cancer immunotherapy

BACKGROUND

Adoptive cell cancer therapies aim to re-engineer a patient's immune cells to mount an anti-cancer response. Chimeric antigen receptor T and natural killer cells have been engineered and proved successful in treating some cancers; however, the genetic methods for engineering are laborious, expensive, and inefficient and can cause severe toxicities when they over-proliferate.

RESULTS

We examined whether the cell-killing capacity of activated T and NK cells could be targeted to cancer cells by anchoring antibodies to their cell surface. Using metabolic glycoengineering to introduce azide moieties to the cellular surface, we covalently attached a dibenzocyclooctyne-modified antibody using the strain-promoted alkyne azide cycloaddition reaction, creating antibody-conjugated T and NK cells. We targeted the immune cells to tumors possessing the xenoantigen, N-glycolyl neuraminic acid GM3 ganglioside, using the 14F7hT antibody. These activated T and NK cells are "armed" with tumour-homing capabilities that specifically lyses antigen-positive cancer cells without off-target toxicities. Moreover, when exposed to target cells, 14F7hT-conjugated T cells that are not preactivated exhibit increased perforin, granzyme, CD69, and CD25 expression and specific cell killing.

CONCLUSIONS

This research shows the potential for a non-genetic method for redirecting cytotoxic immune cells as a feasible and effective approach for tumor-targeted cell immunotherapy.

Synthetic DNA for Cell Surface Engineering: Experimental Comparison between Click Conjugation and Lipid Insertion in Terms of Cell Viability, Engineering Efficiency, and Displaying Stability

The cell surface can be engineered with synthetic DNA for various applications ranging from cancer immunotherapy to tissue engineering. However, while elegant methods such as click conjugation and lipid insertion have been developed to engineer the cell surface with DNA, little effort has been made to systematically evaluate and compare these methods. Resultantly, it is often challenging to choose a right method for a certain application or to interpret data from different studies. In this study, we systematically evaluated click conjugation and lipid insertion in terms of cell viability, engineering efficiency, and displaying stability. Cells engineered with both methods can maintain high viability when the concentration of modified DNA is less than 25-50 μM. However, lipid insertion is faster and more efficient in displaying DNA on the cell surface than click conjugation. The efficiency of displaying DNA with lipid insertion is 10-40 times higher than that with click conjugation for a large range of DNA concentration. However, the half-life of physically inserted DNA on the cell surface is 3-4 times lower than that of covalently conjugated DNA, which depends on the working temperature. While the half-life of physically inserted DNA molecules on the cell surface is shorter than that of DNA molecules clicked onto the cell surface, lipid insertion is more effective than click conjugation in the promotion of cell-cell interactions under the two different experimental settings. The data acquired in this work are expected to act as a guideline for choosing an approximate method for engineering the cell surface with synthetic DNA or even other biomolecules.

Equipping Natural Killer Cells with Cetuximab through Metabolic Glycoengineering and Bioorthogonal Reaction for Targeted Treatment of KRAS Mutant Colorectal Cancer

While Cetuximab can be used to treat KRAS wild-type colon cancer cells by targeting EGFR and inhibiting the activation of downstream signaling pathways, it exhibits little therapeutic effect on KRAS mutant colon cancer cells. Natural killer (NK) cells are a class of powerful immune cells with anticancer activities. However, NK cells typically lack inherent tumor targeting abilities. Here, a new method is established to bestow NK-92 cells with tumor targeting abilities by installing cetuximab on the cell surface. Through metabolic glycoengineering, azide groups were introduced onto the surface of NK-92 cells. Bioorthogonal strain promoted the azide-alkyne cycloaddition click reaction of engineered NK-92 cells with alkyne modified cetuximab functionalized NK cells with the antibody. The resulting NK-92 cells were significantly more effective than the parent NK-92 cells in protecting against tumor development in a KRAS mutant mouse tumor model resistant to cetuximab treatment. Thus, NK cell functionalization with antibodies enabled by metabolic glycoengineering is a promising strategy to enhance anticancer immune therapy.