Redirection of CAR‑T Cell Cytotoxicity Using Metabolic Glycan Labeling with Unnatural Sugars

T cells expressing chimeric antigen receptors (CAR-T
cells) have
shown unprecedented clinical responses against hematological malignancies.
However, some patients relapse after CAR-T cell therapy due to antigen-negative
escape variants. Additionally, CAR-T cell therapies showed limited
clinical efficacy in solid tumors with high antigen heterogeneity.
To overcome this, we metabolically labeled the glycans on cancer cells
to redirect CAR-T cell cytotoxicity regardless of the endogenous antigen
expression status of the cancer cells. We found that modifying cancer
cells with N-azidoacetylmannosamine and bicyclo[6.1.0]non-4-yne-fluorescein
isothiocyanate can elicit selective and durable cytotoxicity of anti-FITC
CAR-T cells. Furthermore, we demonstrated that dinitrophenyl-conjugated
sialic acid (Sia-DNP) generated DNP-modified glycans on cancer cells
in situ that could be effectively targeted by anti-DNP CAR-T cells
to eradicate established tumors in xenograft models. Our study illustrates
that metabolic glycan labeling using unnatural sugars can be combined
with CAR-T cell therapy to provide novel cancer immunotherapy for
solid tumors that lack viable target antigens.